Add cloud-init user data support via Linode Metadata (#4)

* feat: support metadata user data

Co-authored-by: lots0logs <4675662+lots0logs@users.noreply.github.com>

* fix: address cloud-init review comments

Agent-Logs-Url: https://github.com/lots0logs/docker-machine-driver-linode/sessions/7c66e84c-87fb-4861-ab2d-8874c175f8f5

Co-authored-by: lots0logs <4675662+lots0logs@users.noreply.github.com>

---------

Co-authored-by: openai-code-agent[bot] <242516109+Codex@users.noreply.github.com>
Co-authored-by: lots0logs <4675662+lots0logs@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: 3 people

README.md

@@ -62,6 +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-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

@@ -51,7 +51,9 @@ type Driver struct {
 	StackScriptLabel string
 	StackScriptData  map[string]string
 
-	Tags string
+	// UserData contains base64-encoded cloud-init user data for the Linode Metadata service.
+	UserData string
+	Tags     string
 }
 
 // VERSION represents the semver version of the package
@@ -221,6 +223,11 @@ func (d *Driver) GetCreateFlags() []mcnflag.Flag {
 			Usage:  "A JSON string specifying data for the selected StackScript",
 			Value:  "",
 		},
+		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)",
+		},
 		mcnflag.BoolFlag{
 			EnvVar: "LINODE_CREATE_PRIVATE_IP",
 			Name:   "linode-create-private-ip",
@@ -279,6 +286,16 @@ func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 	d.UserAgentPrefix = flags.String("linode-ua-prefix")
 	d.Tags = flags.String("linode-tags")
 
+	userData := flags.String("linode-user-data")
+	if userData != "" {
+		encodedUserData, err := encodeUserData(userData)
+		if err != nil {
+			return err
+		}
+
+		d.UserData = encodedUserData
+	}
+
 	d.SetSwarmConfigFromFlags(flags)
 
 	if d.APIToken == "" {
@@ -323,6 +340,28 @@ func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 	return nil
 }
 
+func encodeUserData(userData string) (string, error) {
+	if userData == "" {
+		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)
+		}
+
+		userData = string(content)
+	}
+
+	return base64.StdEncoding.EncodeToString([]byte(userData)), nil
+}
+
 // PreCreateCheck allows for pre-create operations to make sure a driver is ready for creation
 func (d *Driver) PreCreateCheck() error {
 	// TODO(displague) linode-stackscript-file should be read and uploaded (private), then used for boot.
@@ -426,6 +465,12 @@ func (d *Driver) Create() error {
 		log.Infof("Using StackScript %d: %s/%s", d.StackScriptID, d.StackScriptUser, d.StackScriptLabel)
 	}
 
+	if d.UserData != "" {
+		createOpts.Metadata = &linodego.InstanceMetadataOptions{
+			UserData: d.UserData,
+		}
+	}
+
 	linode, err := client.CreateInstance(context.TODO(), createOpts)
 	if err != nil {
 		return err

pkg/drivers/linode/linode_test.go

@@ -1,7 +1,10 @@
 package linode
 
 import (
+	"encoding/base64"
 	"net"
+	"os"
+	"path/filepath"
 	"reflect"
 	"testing"
 
@@ -27,6 +30,86 @@ 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("", "")
+
+	dir := t.TempDir()
+	userDataPath := filepath.Join(dir, "user-data.yaml")
+	userData := "#cloud-config\npackages:\n  - curl\n"
+	if err := os.WriteFile(userDataPath, []byte(userData), 0o600); err != nil {
+		t.Fatalf("failed to write user data fixture: %s", err)
+	}
+
+	checkFlags := &drivers.CheckDriverOptions{
+		FlagsValues: map[string]interface{}{
+			"linode-token":     "PROJECT",
+			"linode-root-pass": "ROOTPASS",
+			"linode-user-data": "@" + userDataPath,
+		},
+		CreateFlags: driver.GetCreateFlags(),
+	}
+
+	err := driver.SetConfigFromFlags(checkFlags)
+
+	assert.NoError(t, err)
+	assert.Equal(t, base64.StdEncoding.EncodeToString([]byte(userData)), driver.UserData)
+}
+
+func TestSetConfigFromFlagsUserDataMissingFile(t *testing.T) {
+	driver := NewDriver("", "")
+
+	checkFlags := &drivers.CheckDriverOptions{
+		FlagsValues: map[string]interface{}{
+			"linode-token":     "PROJECT",
+			"linode-root-pass": "ROOTPASS",
+			"linode-user-data": "@/does/not/exist",
+		},
+		CreateFlags: driver.GetCreateFlags(),
+	}
+
+	err := driver.SetConfigFromFlags(checkFlags)
+
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "--linode-user-data")
+}
+
+func TestSetConfigFromFlagsUserDataEmptyPath(t *testing.T) {
+	driver := NewDriver("", "")
+
+	checkFlags := &drivers.CheckDriverOptions{
+		FlagsValues: map[string]interface{}{
+			"linode-token":     "PROJECT",
+			"linode-root-pass": "ROOTPASS",
+			"linode-user-data": "@",
+		},
+		CreateFlags: driver.GetCreateFlags(),
+	}
+
+	err := driver.SetConfigFromFlags(checkFlags)
+
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "--linode-user-data")
+}
+
 func TestPrivateIP(t *testing.T) {
 	ip := net.IP{}
 	for _, addr := range [][]byte{