diff --git a/role_scripts/10/primary/start.sh b/role_scripts/10/primary/start.sh
index 81d7b7c..62ffbfc 100755
--- a/role_scripts/10/primary/start.sh
+++ b/role_scripts/10/primary/start.sh
@@ -180,24 +180,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 # ref: https://superuser.com/a/246841/985093
 cat /tmp/postgresql.conf $PGDATA/postgresql.conf >"/tmp/postgresql.conf.tmp" && mv "/tmp/postgresql.conf.tmp" "$PGDATA/postgresql.conf"
diff --git a/role_scripts/10/standby/ha_backup_job.sh b/role_scripts/10/standby/ha_backup_job.sh
index f38682d..d4c1064 100755
--- a/role_scripts/10/standby/ha_backup_job.sh
+++ b/role_scripts/10/standby/ha_backup_job.sh
@@ -98,24 +98,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/10/standby/run.sh b/role_scripts/10/standby/run.sh
index da7dc4d..31a441c 100755
--- a/role_scripts/10/standby/run.sh
+++ b/role_scripts/10/standby/run.sh
@@ -163,24 +163,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/10/standby/warm_stanby.sh b/role_scripts/10/standby/warm_stanby.sh
index 518c8ed..aa7a7d4 100755
--- a/role_scripts/10/standby/warm_stanby.sh
+++ b/role_scripts/10/standby/warm_stanby.sh
@@ -39,24 +39,35 @@ echo "hot_standby = off" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/11/primary/start.sh b/role_scripts/11/primary/start.sh
index 7327172..88639ca 100755
--- a/role_scripts/11/primary/start.sh
+++ b/role_scripts/11/primary/start.sh
@@ -221,24 +221,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 # ref: https://superuser.com/a/246841/985093
 cat /tmp/postgresql.conf $PGDATA/postgresql.conf >"/tmp/postgresql.conf.tmp" && mv "/tmp/postgresql.conf.tmp" "$PGDATA/postgresql.conf"
diff --git a/role_scripts/11/standby/ha_backup_job.sh b/role_scripts/11/standby/ha_backup_job.sh
index 6ad580a..f5083be 100755
--- a/role_scripts/11/standby/ha_backup_job.sh
+++ b/role_scripts/11/standby/ha_backup_job.sh
@@ -97,24 +97,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/11/standby/run.sh b/role_scripts/11/standby/run.sh
index 1f557c8..4eb0a72 100755
--- a/role_scripts/11/standby/run.sh
+++ b/role_scripts/11/standby/run.sh
@@ -166,24 +166,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/11/standby/warm_stanby.sh b/role_scripts/11/standby/warm_stanby.sh
index ba5a474..006617f 100755
--- a/role_scripts/11/standby/warm_stanby.sh
+++ b/role_scripts/11/standby/warm_stanby.sh
@@ -39,24 +39,35 @@ echo "shared_preload_libraries = 'pg_stat_statements'" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/12/primary/start.sh b/role_scripts/12/primary/start.sh
index d78266f..d11f018 100755
--- a/role_scripts/12/primary/start.sh
+++ b/role_scripts/12/primary/start.sh
@@ -241,24 +241,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 # ref: https://superuser.com/a/246841/985093
diff --git a/role_scripts/12/standby/ha_backup_job.sh b/role_scripts/12/standby/ha_backup_job.sh
index 4d645a9..1ae79cc 100755
--- a/role_scripts/12/standby/ha_backup_job.sh
+++ b/role_scripts/12/standby/ha_backup_job.sh
@@ -99,24 +99,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/12/standby/run.sh b/role_scripts/12/standby/run.sh
index dbaff6e..d60ff98 100755
--- a/role_scripts/12/standby/run.sh
+++ b/role_scripts/12/standby/run.sh
@@ -166,24 +166,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/12/standby/warm_stanby.sh b/role_scripts/12/standby/warm_stanby.sh
index 20a73ac..7c182c6 100755
--- a/role_scripts/12/standby/warm_stanby.sh
+++ b/role_scripts/12/standby/warm_stanby.sh
@@ -48,24 +48,35 @@ echo "hot_standby = off" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/13/primary/start.sh b/role_scripts/13/primary/start.sh
index 0675b8d..50e446c 100755
--- a/role_scripts/13/primary/start.sh
+++ b/role_scripts/13/primary/start.sh
@@ -271,24 +271,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 # ref: https://superuser.com/a/246841/985093
diff --git a/role_scripts/13/standby/ha_backup_job.sh b/role_scripts/13/standby/ha_backup_job.sh
index b62d3c2..9dbdf52 100755
--- a/role_scripts/13/standby/ha_backup_job.sh
+++ b/role_scripts/13/standby/ha_backup_job.sh
@@ -99,24 +99,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/13/standby/run.sh b/role_scripts/13/standby/run.sh
index 17a6a74..259d4f7 100755
--- a/role_scripts/13/standby/run.sh
+++ b/role_scripts/13/standby/run.sh
@@ -169,24 +169,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/13/standby/warm_stanby.sh b/role_scripts/13/standby/warm_stanby.sh
index 6eb8c8d..f77be34 100755
--- a/role_scripts/13/standby/warm_stanby.sh
+++ b/role_scripts/13/standby/warm_stanby.sh
@@ -42,24 +42,35 @@ echo "shared_preload_libraries = 'pg_stat_statements'" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/14/primary/start.sh b/role_scripts/14/primary/start.sh
index 2202449..9bff7aa 100755
--- a/role_scripts/14/primary/start.sh
+++ b/role_scripts/14/primary/start.sh
@@ -278,24 +278,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 # ref: https://superuser.com/a/246841/985093
diff --git a/role_scripts/14/standby/ha_backup_job.sh b/role_scripts/14/standby/ha_backup_job.sh
index 28bffd8..5038380 100755
--- a/role_scripts/14/standby/ha_backup_job.sh
+++ b/role_scripts/14/standby/ha_backup_job.sh
@@ -99,24 +99,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/14/standby/run.sh b/role_scripts/14/standby/run.sh
index 36b7f92..74ea25a 100755
--- a/role_scripts/14/standby/run.sh
+++ b/role_scripts/14/standby/run.sh
@@ -169,25 +169,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-# https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    # this needs to be changed for read replicas
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/14/standby/warm_stanby.sh b/role_scripts/14/standby/warm_stanby.sh
index 26e12bf..df05ee9 100755
--- a/role_scripts/14/standby/warm_stanby.sh
+++ b/role_scripts/14/standby/warm_stanby.sh
@@ -42,24 +42,35 @@ echo "shared_preload_libraries = 'pg_stat_statements'" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/15/primary/start.sh b/role_scripts/15/primary/start.sh
index 6bc863b..5f73009 100755
--- a/role_scripts/15/primary/start.sh
+++ b/role_scripts/15/primary/start.sh
@@ -279,24 +279,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 # ref: https://superuser.com/a/246841/985093
diff --git a/role_scripts/15/standby/ha_backup_job.sh b/role_scripts/15/standby/ha_backup_job.sh
index 2480264..040a43c 100755
--- a/role_scripts/15/standby/ha_backup_job.sh
+++ b/role_scripts/15/standby/ha_backup_job.sh
@@ -101,24 +101,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/15/standby/run.sh b/role_scripts/15/standby/run.sh
index 92bdf71..2db653a 100755
--- a/role_scripts/15/standby/run.sh
+++ b/role_scripts/15/standby/run.sh
@@ -168,25 +168,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-# https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    # this needs to be changed for read replicas
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/15/standby/warm_stanby.sh b/role_scripts/15/standby/warm_stanby.sh
index 65bd3d1..d6ae859 100755
--- a/role_scripts/15/standby/warm_stanby.sh
+++ b/role_scripts/15/standby/warm_stanby.sh
@@ -43,24 +43,35 @@ echo "shared_preload_libraries = 'pg_stat_statements'" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/16/primary/start.sh b/role_scripts/16/primary/start.sh
index a063073..5dc2a7b 100755
--- a/role_scripts/16/primary/start.sh
+++ b/role_scripts/16/primary/start.sh
@@ -277,24 +277,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 # ref: https://superuser.com/a/246841/985093
diff --git a/role_scripts/16/standby/ha_backup_job.sh b/role_scripts/16/standby/ha_backup_job.sh
index fe94164..e9c8003 100755
--- a/role_scripts/16/standby/ha_backup_job.sh
+++ b/role_scripts/16/standby/ha_backup_job.sh
@@ -101,24 +101,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/16/standby/run.sh b/role_scripts/16/standby/run.sh
index 55e420d..7a865db 100755
--- a/role_scripts/16/standby/run.sh
+++ b/role_scripts/16/standby/run.sh
@@ -170,24 +170,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/16/standby/warm_stanby.sh b/role_scripts/16/standby/warm_stanby.sh
index 9ad3eeb..a1eff58 100755
--- a/role_scripts/16/standby/warm_stanby.sh
+++ b/role_scripts/16/standby/warm_stanby.sh
@@ -43,24 +43,35 @@ echo "shared_preload_libraries = 'pg_stat_statements'" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/17/primary/start.sh b/role_scripts/17/primary/start.sh
index d636bb6..0eae773 100755
--- a/role_scripts/17/primary/start.sh
+++ b/role_scripts/17/primary/start.sh
@@ -282,24 +282,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 # ref: https://superuser.com/a/246841/985093
diff --git a/role_scripts/17/standby/ha_backup_job.sh b/role_scripts/17/standby/ha_backup_job.sh
index fe94164..e9c8003 100755
--- a/role_scripts/17/standby/ha_backup_job.sh
+++ b/role_scripts/17/standby/ha_backup_job.sh
@@ -101,24 +101,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/17/standby/run.sh b/role_scripts/17/standby/run.sh
index 9e774f2..5e54fe0 100755
--- a/role_scripts/17/standby/run.sh
+++ b/role_scripts/17/standby/run.sh
@@ -171,25 +171,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    # this needs to be changed for read replicas
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/17/standby/warm_stanby.sh b/role_scripts/17/standby/warm_stanby.sh
index 9ad3eeb..a1eff58 100755
--- a/role_scripts/17/standby/warm_stanby.sh
+++ b/role_scripts/17/standby/warm_stanby.sh
@@ -43,24 +43,35 @@ echo "shared_preload_libraries = 'pg_stat_statements'" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/18/primary/start.sh b/role_scripts/18/primary/start.sh
index 7610a4a..85c91fc 100755
--- a/role_scripts/18/primary/start.sh
+++ b/role_scripts/18/primary/start.sh
@@ -275,24 +275,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 # ref: https://superuser.com/a/246841/985093
diff --git a/role_scripts/18/standby/ha_backup_job.sh b/role_scripts/18/standby/ha_backup_job.sh
index fe94164..e9c8003 100755
--- a/role_scripts/18/standby/ha_backup_job.sh
+++ b/role_scripts/18/standby/ha_backup_job.sh
@@ -101,24 +101,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 if [[ "${SSL:-0}" == "ON" ]]; then
     echo "ssl = on" >>/tmp/postgresql.conf
diff --git a/role_scripts/18/standby/run.sh b/role_scripts/18/standby/run.sh
index 9e774f2..5e54fe0 100755
--- a/role_scripts/18/standby/run.sh
+++ b/role_scripts/18/standby/run.sh
@@ -171,25 +171,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    # this needs to be changed for read replicas
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/18/standby/warm_stanby.sh b/role_scripts/18/standby/warm_stanby.sh
index 9ad3eeb..a1eff58 100755
--- a/role_scripts/18/standby/warm_stanby.sh
+++ b/role_scripts/18/standby/warm_stanby.sh
@@ -43,24 +43,35 @@ echo "shared_preload_libraries = 'pg_stat_statements'" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=${HOSTNAME##*[!0-9]}
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=${names%,}
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/9/primary/start.sh b/role_scripts/9/primary/start.sh
index 7bd5a5b..9978c85 100755
--- a/role_scripts/9/primary/start.sh
+++ b/role_scripts/9/primary/start.sh
@@ -175,24 +175,35 @@ fi
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 # ref: https://superuser.com/a/246841/985093
diff --git a/role_scripts/9/standby/ha_backup_job.sh b/role_scripts/9/standby/ha_backup_job.sh
index 27e68fd..28c891b 100755
--- a/role_scripts/9/standby/ha_backup_job.sh
+++ b/role_scripts/9/standby/ha_backup_job.sh
@@ -99,24 +99,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/9/standby/run.sh b/role_scripts/9/standby/run.sh
index d4f8c67..5b47a9f 100755
--- a/role_scripts/9/standby/run.sh
+++ b/role_scripts/9/standby/run.sh
@@ -158,24 +158,35 @@ else
 fi
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then
diff --git a/role_scripts/9/standby/warm_stanby.sh b/role_scripts/9/standby/warm_stanby.sh
index 32d18e9..48184af 100755
--- a/role_scripts/9/standby/warm_stanby.sh
+++ b/role_scripts/9/standby/warm_stanby.sh
@@ -40,24 +40,35 @@ echo "hot_standby = off" >>/tmp/postgresql.conf
 
 if [[ "$STREAMING" == "synchronous" ]]; then
     # setup synchronous streaming replication
-    echo "synchronous_commit = remote_write" >>/tmp/postgresql.conf
-
-    # https://stackoverflow.com/a/44092231/244009
-    self_idx=$(echo $HOSTNAME | grep -Eo '[0-9]+$')
-    echo "$self_idx"
-
-    shopt -s extglob
-    sts_prefix=${HOSTNAME%%+([0-9])}
-    names=""
-    for ((i = 0; i < $REPLICAS; i++)); do
-        if [[ $self_idx == $i ]]; then
-            echo "skip $i"
-        else
-            names+="\"$sts_prefix$i\","
-        fi
-    done
-    names=$(echo "$names" | rev | cut -c2- | rev)
-    echo "synchronous_standby_names = 'ANY 1 ("$names")'" >>/tmp/postgresql.conf
+    echo "synchronous_commit = ${SYNC_COMMIT_LEVEL:-remote_write}" >>/tmp/postgresql.conf
+
+    if [[ "${SYNC_USE_WILDCARD:-false}" == "true" ]]; then
+        names="*"
+    elif [[ -n "${SYNC_STANDBY_NAMES:-}" ]]; then
+        names=""
+        IFS=',' read -ra _standby_list <<< "$SYNC_STANDBY_NAMES"
+        for _name in "${_standby_list[@]}"; do
+            names+="\"${_name}\"",
+        done
+        names="${names%,}"
+    else
+        # https://stackoverflow.com/a/44092231/244009
+        self_idx=${HOSTNAME##*[!0-9]}
+        echo "$self_idx"
+
+        shopt -s extglob
+        sts_prefix=${HOSTNAME%%+([0-9])}
+        names=""
+        for ((i = 0; i < $REPLICAS; i++)); do
+            if [[ $self_idx == $i ]]; then
+                echo "skip $i"
+            else
+                names+="\"$sts_prefix$i\"",
+            fi
+        done
+        names=${names%,}
+    fi
+    echo "synchronous_standby_names = '${SYNC_REPLICATION_MODE:-ANY} ${NUM_SYNC_REPLICAS:-1} ("$names")'" >>/tmp/postgresql.conf
 fi
 
 if [[ "${SSL:-0}" == "ON" ]]; then