fix(dgraphtest): give Zero the admin whitelist the Alpha already gets

dgraphtest/dgraph.go

@@ -142,6 +142,21 @@ func (z *zero) cmd(c *LocalCluster) []string {
 	if c.lowerThanV21 {
 		zcmd = append(zcmd, fmt.Sprintf(`--idx=%v`, z.id+1), "--telemetry=false")
 	} else {
+		// Zero's destructive admin endpoints (/moveTablet, /removeNode) are guarded
+		// unconditionally: with neither a token nor a whitelist configured, only a
+		// loopback caller is admitted. A test reaching Zero through a published
+		// container port is not loopback, so without this the harness cannot exercise
+		// those endpoints at all — see adminAuthHandler in dgraph/cmd/zero/admin.go.
+		//
+		// Same value the Alpha already gets, for the same reason: the harness is not
+		// the place to enforce network policy, and a test cluster that refuses its own
+		// control plane fails in a way that looks nothing like its cause.
+		security := `--security=whitelist=0.0.0.0/0`
+		if c.conf.securityToken != "" {
+			security += fmt.Sprintf(`;token=%s`, c.conf.securityToken)
+		}
+		zcmd = append(zcmd, security)
+
 		zcmd = append(zcmd, fmt.Sprintf(`--raft=idx=%v`, z.id+1), "--telemetry=reports=false;",
 			fmt.Sprintf(`--limit=refill-interval=%v;uid-lease=%v`, c.conf.refillInterval, c.conf.uidLease))
 	}

dgraphtest/dgraph_test.go

@@ -0,0 +1,66 @@
+/*
+ * SPDX-FileCopyrightText: © 2017-2026 Istari Digital, Inc.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package dgraphtest
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// TestZeroCmdCarriesSecurityWhitelist pins that the harness configures Zero's admin
+// whitelist, not only the Alpha's.
+//
+// Zero guards /moveTablet and /removeNode with adminAuthHandler(strict=true), which
+// applies whether or not --security is configured: with neither a token nor a
+// whitelist, only a loopback caller is admitted. A test process reaching Zero through
+// a published container port is not loopback, so a harness that omits this cannot
+// exercise those endpoints at all — every call returns 401 ErrorUnauthorized.
+//
+// This is asserted on the COMMAND rather than end to end, deliberately. Whether the
+// container observes a loopback peer depends on the host's Docker networking: on Linux
+// a published port arrives from the bridge gateway and the guard fires, while on
+// Docker Desktop it can arrive as loopback and the guard never fires. An integration
+// test would therefore pass on some developer machines no matter what the harness
+// passes, which is worse than no test. The guard's own behaviour is already covered by
+// the adminAuthHandler unit tests in dgraph/cmd/zero.
+func TestZeroCmdCarriesSecurityWhitelist(t *testing.T) {
+	c := &LocalCluster{conf: NewClusterConfig()}
+	z := &zero{id: 0, aliasName: "zero0"}
+
+	cmd := strings.Join(z.cmd(c), " ")
+	require.Contains(t, cmd, "--security=whitelist=",
+		"Zero must get an admin whitelist, or the harness cannot reach /moveTablet and "+
+			"/removeNode: they are guarded with strict=true, so without it only a loopback "+
+			"caller is admitted")
+}
+
+// TestZeroCmdCarriesSecurityToken: when a test configures a token, Zero has to know it
+// too. Zero authorizes an admin request on the token OR the whitelist, so a cluster
+// where only the Alpha knows the token is incoherent rather than merely stricter.
+func TestZeroCmdCarriesSecurityToken(t *testing.T) {
+	const token = "shhh"
+	c := &LocalCluster{conf: NewClusterConfig().WithSecurityToken(token)}
+	z := &zero{id: 0, aliasName: "zero0"}
+
+	cmd := strings.Join(z.cmd(c), " ")
+	require.Contains(t, cmd, "token="+token,
+		"Zero must be told the configured --security token, as the Alpha already is")
+}
+
+// TestZeroCmdPreV21OmitsSecurity. Pre-v21 binaries predate both the --security
+// superflag and the admin guard, so passing the flag there would fail an upgrade test
+// with an unknown-flag error while fixing nothing. The Alpha's command makes the same
+// split for the same reason.
+func TestZeroCmdPreV21OmitsSecurity(t *testing.T) {
+	c := &LocalCluster{conf: NewClusterConfig(), lowerThanV21: true}
+	z := &zero{id: 0, aliasName: "zero0"}
+
+	cmd := strings.Join(z.cmd(c), " ")
+	require.NotContains(t, cmd, "--security",
+		"a pre-v21 Zero does not understand --security and would fail to start")
+}