fix: require file-backed linode user data

Author: lots0logs

README.md

@@ -62,7 +62,7 @@ docker-machine create -d linode --linode-token=<linode-token> linode
 | `linode-swap-size` | `LINODE_SWAP_SIZE` | `512` | The amount of swap space provisioned on the Linode Instance
 | `linode-stackscript` | `LINODE_STACKSCRIPT` | None | Specifies the Linode StackScript to use to create the instance, either by numeric ID, or using the form *username*/*label*.
 | `linode-stackscript-data` | `LINODE_STACKSCRIPT_DATA` | None | A JSON string specifying data that is passed (via UDF) to the selected StackScript.
-| `linode-user-data` | `LINODE_USER_DATA` | None | Cloud-init user data passed to the Linode Metadata service; use inline content or prefix with `@` to read from a file. Content is base64-encoded automatically.
+| `linode-user-data` | `LINODE_USER_DATA` | None | Path to a cloud-init user-data file passed to the Linode Metadata service. File contents are base64-encoded automatically.
 | `linode-create-private-ip` | `LINODE_CREATE_PRIVATE_IP` | None | A flag specifying to create private IP for the Linode instance.
 | `linode-tags` | `LINODE_TAGS` | None | A comma separated list of tags to apply to the Linode resource
 | `linode-ua-prefix` | `LINODE_UA_PREFIX` | None | Prefix the User-Agent in Linode API calls with some 'product/version'

pkg/drivers/linode/linode.go

@@ -226,7 +226,7 @@ func (d *Driver) GetCreateFlags() []mcnflag.Flag {
 		mcnflag.StringFlag{
 			EnvVar: "LINODE_USER_DATA",
 			Name:   "linode-user-data",
-			Usage:  "Cloud-init user data for the Linode Metadata service (inline or @path to file)",
+			Usage:  "Path to a cloud-init user-data file for the Linode Metadata service",
 		},
 		mcnflag.BoolFlag{
 			EnvVar: "LINODE_CREATE_PRIVATE_IP",
@@ -345,21 +345,17 @@ func encodeUserData(userData string) (string, error) {
 		return "", nil
 	}
 
-	if strings.HasPrefix(userData, "@") {
-		path := strings.TrimSpace(strings.TrimPrefix(userData, "@"))
-		if path == "" {
-			return "", fmt.Errorf("--linode-user-data requires a file path after '@'")
-		}
-
-		content, err := os.ReadFile(path)
-		if err != nil {
-			return "", fmt.Errorf("failed to read user data from --linode-user-data file %q: %w", path, err)
-		}
+	path := strings.TrimSpace(userData)
+	if path == "" {
+		return "", fmt.Errorf("--linode-user-data requires a file path")
+	}
 
-		userData = string(content)
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return "", fmt.Errorf("failed to read user data from --linode-user-data file %q: %w", path, err)
 	}
 
-	return base64.StdEncoding.EncodeToString([]byte(userData)), nil
+	return base64.StdEncoding.EncodeToString(content), nil
 }
 
 // PreCreateCheck allows for pre-create operations to make sure a driver is ready for creation

pkg/drivers/linode/linode_test.go

@@ -30,25 +30,6 @@ func TestSetConfigFromFlags(t *testing.T) {
 	assert.Empty(t, checkFlags.InvalidFlags)
 }
 
-func TestSetConfigFromFlagsUserDataInline(t *testing.T) {
-	driver := NewDriver("", "")
-
-	userData := "#cloud-config\npackages:\n - htop\n"
-	checkFlags := &drivers.CheckDriverOptions{
-		FlagsValues: map[string]interface{}{
-			"linode-token":     "PROJECT",
-			"linode-root-pass": "ROOTPASS",
-			"linode-user-data": userData,
-		},
-		CreateFlags: driver.GetCreateFlags(),
-	}
-
-	err := driver.SetConfigFromFlags(checkFlags)
-
-	assert.NoError(t, err)
-	assert.Equal(t, base64.StdEncoding.EncodeToString([]byte(userData)), driver.UserData)
-}
-
 func TestSetConfigFromFlagsUserDataFile(t *testing.T) {
 	driver := NewDriver("", "")
 
@@ -63,7 +44,7 @@ func TestSetConfigFromFlagsUserDataFile(t *testing.T) {
 		FlagsValues: map[string]interface{}{
 			"linode-token":     "PROJECT",
 			"linode-root-pass": "ROOTPASS",
-			"linode-user-data": "@" + userDataPath,
+			"linode-user-data": userDataPath,
 		},
 		CreateFlags: driver.GetCreateFlags(),
 	}
@@ -81,7 +62,7 @@ func TestSetConfigFromFlagsUserDataMissingFile(t *testing.T) {
 		FlagsValues: map[string]interface{}{
 			"linode-token":     "PROJECT",
 			"linode-root-pass": "ROOTPASS",
-			"linode-user-data": "@/does/not/exist",
+			"linode-user-data": "/does/not/exist",
 		},
 		CreateFlags: driver.GetCreateFlags(),
 	}
@@ -99,7 +80,7 @@ func TestSetConfigFromFlagsUserDataEmptyPath(t *testing.T) {
 		FlagsValues: map[string]interface{}{
 			"linode-token":     "PROJECT",
 			"linode-root-pass": "ROOTPASS",
-			"linode-user-data": "@",
+			"linode-user-data": "   ",
 		},
 		CreateFlags: driver.GetCreateFlags(),
 	}