feat: support mount and secret injection for provider extensions (fix…

AI_AGENT_DISCLOSURE.md

@@ -0,0 +1,3 @@
+This contribution was prepared by an AI agent acting on a human's behalf.
+The human submitter may not have independently reviewed or tested the change.
+2026-09-16

docs/examples/provider.go

@@ -40,8 +40,10 @@ func main() {
 }
 
 type options struct {
-	db   string
-	size int
+	db      string
+	size    int
+	mounts  []string
+	secrets []string
 }
 
 func composeCommand() *cobra.Command {
@@ -65,6 +67,8 @@ func composeCommand() *cobra.Command {
 	upCmd.Flags().IntVar(&options.size, "size", 10, "Database size in GB")
 	upCmd.Flags().String("name", "", "Name of the database to be created")
 	_ = upCmd.MarkFlagRequired("name")
+	upCmd.Flags().StringSliceVar(&options.mounts, "mount", nil, "Volume mount to inject (format: source:target)")
+	upCmd.Flags().StringSliceVar(&options.secrets, "secret", nil, "Secret to inject (format: name=file)")
 
 	downCmd := &cobra.Command{
 		Use:  "down",
@@ -121,6 +125,14 @@ func up(options options, args []string) {
 	}
 	fmt.Printf(`{ "type": "setenv", "message": "URL=https://magic.cloud/%s" }%s`, servicename, lineSeparator)
 	fmt.Printf(`{ "type": "rawsetenv", "message": "CLOUD_REGION=us-east-1" }%s`, lineSeparator)
+	for _, m := range options.mounts {
+		mountMsg, _ := json.Marshal(map[string]string{"type": "mount", "message": m})
+		fmt.Println(string(mountMsg))
+	}
+	for _, s := range options.secrets {
+		secretMsg, _ := json.Marshal(map[string]string{"type": "secret", "message": s})
+		fmt.Println(string(secretMsg))
+	}
 }
 
 func down(_ *cobra.Command, _ []string) {

pkg/compose/executor_ops.go

@@ -79,9 +79,12 @@ func (exec *planExecutor) execRemoveVolume(ctx context.Context, op Operation) er
 func (exec *planExecutor) execCreateContainer(ctx context.Context, node *PlanNode) error {
 	op := node.Operation
 	service := *op.Service
+	if liveService, ok := exec.project.Services[op.Service.Name]; ok {
+		service = liveService
+	}
 	// Detach VolumesFrom from the source slice: resolveServiceReferences mutates
 	// entries in place, and the shallow struct copy still shares the backing array.
-	service.VolumesFrom = slices.Clone(op.Service.VolumesFrom)
+	service.VolumesFrom = slices.Clone(service.VolumesFrom)
 
 	// Resolve service references (network_mode, ipc, pid, volumes_from) to
 	// actual container IDs from the in-memory view, which already includes
@@ -96,9 +99,9 @@ func (exec *planExecutor) execCreateContainer(ctx context.Context, node *PlanNod
 	labels := mergeLabels(service.Labels, service.CustomLabels)
 	if op.Inherited != nil {
 		// This is a recreate: add the replace label
-		replacedName := op.Service.ContainerName
+		replacedName := service.ContainerName
 		if replacedName == "" {
-			replacedName = fmt.Sprintf("%s%s%d", op.Service.Name, api.Separator, op.Number)
+			replacedName = fmt.Sprintf("%s%s%d", service.Name, api.Separator, op.Number)
 		}
 		labels = labels.Add(api.ContainerReplaceLabel, replacedName)
 	}
@@ -120,9 +123,9 @@ func (exec *planExecutor) execCreateContainer(ctx context.Context, node *PlanNod
 	})
 
 	// Make the new container visible to subsequent execCreateContainer calls
-	// that resolve service references against op.Service.Name.
+	// that resolve service references against service.Name.
 	exec.containersMu.Lock()
-	exec.containersByService[op.Service.Name] = append(exec.containersByService[op.Service.Name], ctr)
+	exec.containersByService[service.Name] = append(exec.containersByService[service.Name], ctr)
 	exec.containersMu.Unlock()
 	return nil
 }

pkg/compose/plugins.go

@@ -29,6 +29,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/compose-spec/compose-go/v2/format"
 	"github.com/compose-spec/compose-go/v2/types"
 	"github.com/containerd/errdefs"
 	"github.com/docker/cli/cli-plugins/manager"
@@ -40,8 +41,10 @@ import (
 )
 
 type JsonMessage struct {
-	Type    string `json:"type"`
-	Message string `json:"message,omitempty"`
+	Type    string                     `json:"type"`
+	Message string                     `json:"message,omitempty"`
+	Mount   *types.ServiceVolumeConfig `json:"mount,omitempty"`
+	Secret  *types.ServiceSecretConfig `json:"secret,omitempty"`
 }
 
 const (
@@ -50,6 +53,8 @@ const (
 	SetEnvType                = "setenv"
 	RawSetEnvType             = "rawsetenv"
 	DebugType                 = "debug"
+	MountType                 = "mount"
+	SecretType                = "secret"
 	providerMetadataDirectory = "compose/providers"
 
 	// GetServiceConfigType is a message the provider sends to receive, on
@@ -59,8 +64,11 @@ const (
 )
 
 type pluginVariables struct {
-	prefixed types.Mapping
-	raw      types.Mapping
+	prefixed       types.Mapping
+	raw            types.Mapping
+	mounts         []types.ServiceVolumeConfig
+	secrets        []types.ServiceSecretConfig
+	projectSecrets map[string]types.SecretConfig
 }
 
 var mux sync.Mutex
@@ -104,6 +112,23 @@ func (s *composeService) runPlugin(ctx context.Context, project *types.Project,
 				}
 				s.Environment[key] = &val
 			}
+			if len(variables.mounts) > 0 {
+				s.Volumes = append(s.Volumes, variables.mounts...)
+			}
+			if len(variables.secrets) > 0 {
+				s.Secrets = append(s.Secrets, variables.secrets...)
+				for _, secret := range variables.secrets {
+					if projSecret, ok := variables.projectSecrets[secret.Source]; ok {
+						if project.Secrets == nil {
+							project.Secrets = make(types.Secrets)
+						}
+						if existing, ok := project.Secrets[secret.Source]; ok && (existing.File != projSecret.File || existing.Environment != projSecret.Environment || existing.Name != projSecret.Name) {
+							logrus.Warnf("provider %q overrides secret %q in project", service.Name, secret.Source)
+						}
+						project.Secrets[secret.Source] = projSecret
+					}
+				}
+			}
 			project.Services[name] = s
 		}
 	}
@@ -180,8 +205,9 @@ func (s *composeService) executePlugin(cmd *exec.Cmd, command string, service ty
 	defer func() { _ = stdout.Close() }()
 
 	variables := pluginVariables{
-		prefixed: types.Mapping{},
-		raw:      types.Mapping{},
+		prefixed:       types.Mapping{},
+		raw:            types.Mapping{},
+		projectSecrets: map[string]types.SecretConfig{},
 	}
 
 	for {
@@ -226,6 +252,42 @@ func (s *composeService) executePlugin(cmd *exec.Cmd, command string, service ty
 			}()
 		case DebugType:
 			logrus.Debugf("%s: %s", service.Name, msg.Message)
+		case MountType:
+			if msg.Mount != nil {
+				variables.mounts = append(variables.mounts, *msg.Mount)
+			} else {
+				volume, err := format.ParseVolume(msg.Message)
+				if err != nil {
+					return pluginVariables{}, fmt.Errorf("invalid response from plugin (expected valid volume string): %s", msg.Message)
+				}
+				variables.mounts = append(variables.mounts, volume)
+			}
+		case SecretType:
+			if msg.Secret != nil {
+				variables.secrets = append(variables.secrets, *msg.Secret)
+				if msg.Secret.Source != "" && msg.Message != "" {
+					variables.projectSecrets[msg.Secret.Source] = types.SecretConfig{
+						Name: msg.Secret.Source,
+						File: msg.Message,
+					}
+				}
+			} else {
+				sep := "="
+				if !strings.Contains(msg.Message, "=") && strings.Contains(msg.Message, ":") {
+					sep = ":"
+				}
+				key, val, found := strings.Cut(msg.Message, sep)
+				if !found {
+					return pluginVariables{}, fmt.Errorf("invalid response from plugin (expected source=file or source:file): %s", msg.Message)
+				}
+				variables.secrets = append(variables.secrets, types.ServiceSecretConfig{
+					Source: key,
+				})
+				variables.projectSecrets[key] = types.SecretConfig{
+					Name: key,
+					File: val,
+				}
+			}
 		default:
 			return pluginVariables{}, fmt.Errorf("invalid response from plugin: %s", msg.Type)
 		}

pkg/compose/plugins_control_test.go

@@ -94,3 +94,66 @@ func TestHelperProviderConfig(t *testing.T) {
 	}
 	os.Exit(0)
 }
+
+func TestExecutePlugin_MountsAndSecrets(t *testing.T) {
+	mockCtrl := gomock.NewController(t)
+	cli := mocks.NewMockCli(mockCtrl)
+	cli.EXPECT().Client().Return(mocks.NewMockAPIClient(mockCtrl)).AnyTimes()
+	svc, err := NewComposeService(cli, WithEventProcessor(noopEventProcessor{}))
+	assert.NilError(t, err)
+
+	cmd := exec.Command(os.Args[0], "-test.run=TestHelperProviderMountsAndSecrets")
+	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
+
+	service := types.ServiceConfig{
+		Name: "db",
+		Provider: &types.ServiceProviderConfig{
+			Type: "test-provider",
+		},
+	}
+	variables, err := svc.(*composeService).executePlugin(cmd, "up", service)
+	assert.NilError(t, err)
+
+	assert.Equal(t, len(variables.mounts), 2)
+	assert.Equal(t, variables.mounts[0].Source, "/host/path")
+	assert.Equal(t, variables.mounts[0].Target, "/container/path")
+	assert.Equal(t, variables.mounts[1].Source, "my-vol")
+	assert.Equal(t, variables.mounts[1].Target, "/data")
+
+	assert.Equal(t, len(variables.secrets), 2)
+	assert.Equal(t, variables.secrets[0].Source, "my_secret")
+	assert.Equal(t, variables.projectSecrets["my_secret"].File, "/tmp/secret1")
+	assert.Equal(t, variables.secrets[1].Source, "other_secret")
+	assert.Equal(t, variables.projectSecrets["other_secret"].File, "/tmp/secret2")
+}
+
+func TestHelperProviderMountsAndSecrets(t *testing.T) {
+	if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+		t.Skip("helper process for TestExecutePlugin_MountsAndSecrets")
+	}
+	emit := func(msg JsonMessage) {
+		if err := json.NewEncoder(os.Stdout).Encode(msg); err != nil {
+			os.Exit(1)
+		}
+	}
+
+	// Mount string format
+	emit(JsonMessage{Type: MountType, Message: "/host/path:/container/path"})
+	// Mount object format
+	emit(JsonMessage{
+		Type: MountType,
+		Mount: &types.ServiceVolumeConfig{
+			Type:   "volume",
+			Source: "my-vol",
+			Target: "/data",
+		},
+	})
+
+	// Secret string format (source=file)
+	emit(JsonMessage{Type: SecretType, Message: "my_secret=/tmp/secret1"})
+	// Secret string format (source:file)
+	emit(JsonMessage{Type: SecretType, Message: "other_secret:/tmp/secret2"})
+
+	os.Exit(0)
+}
+

pkg/e2e/framework.go

@@ -126,10 +126,13 @@ func copyLocalConfig(t testing.TB, configDir string) {
 	t.Helper()
 
 	// copy local config.json if exists
-	localConfig := filepath.Join(os.Getenv("HOME"), ".docker", "config.json")
-	// if no config present just continue
-	if _, err := os.Stat(localConfig); err != nil {
-		// copy the local config.json to the test config dir
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return
+	}
+	localConfig := filepath.Join(home, ".docker", "config.json")
+	// if config present copy to test config dir
+	if _, err := os.Stat(localConfig); err == nil {
 		CopyFile(t, localConfig, filepath.Join(configDir, "config.json"))
 	}
 }

pkg/e2e/providers_test.go

@@ -103,3 +103,41 @@ func TestProviderRawSetEnvOverridesInheritedEnvMapForm(t *testing.T) {
 			OutputContains("test-1  | CLOUD_REGION=us-east-1"),
 			OutputContains("overrides environment variable"))
 }
+
+func TestProviderMountsAndSecrets(t *testing.T) {
+	tmpDir := t.TempDir()
+	mountDir := filepath.Join(tmpDir, "provider-data")
+	secretFile := filepath.Join(tmpDir, "provider-secret")
+	_ = os.MkdirAll(mountDir, 0o755)
+	_ = os.WriteFile(filepath.Join(mountDir, "hello"), []byte("hello from provider mount"), 0o644)
+	_ = os.WriteFile(secretFile, []byte("hello from provider secret"), 0o644)
+
+	// We need to create a test folder for the scenario to pick up the compose.yaml
+	scenarioDir := filepath.Join("testdata", "TestProviderMountsAndSecrets")
+	_ = os.MkdirAll(scenarioDir, 0o755)
+	yamlContent := fmt.Sprintf(`
+services:
+  db:
+    provider:
+      type: example-provider
+      options:
+        type: postgres
+        name: my_db
+        size: 10
+        mount: %s:/provider-data
+        secret: my_secret=%s
+  test:
+    image: alpine
+    depends_on:
+      - db
+    command: sh -c "cat /provider-data/hello && cat /run/secrets/my_secret"
+`, filepath.ToSlash(mountDir), filepath.ToSlash(secretFile))
+	_ = os.WriteFile(filepath.Join(scenarioDir, "compose.yaml"), []byte(yamlContent), 0o644)
+	defer func() { _ = os.RemoveAll(scenarioDir) }() // clean up
+
+	providerScenario(t, "a provider injecting mounts and secrets").
+		Step("the service sees both the mount and the secret",
+			ComposeCmd("up", "--build"),
+			OutputContains("hello from provider mount"),
+			OutputContains("hello from provider secret"))
+}