feat: run pre-entrypoint and post-entrypoint of docker actions (#1106)

A docker action can declare `runs.pre-entrypoint` and `runs.post-entrypoint` next to `runs.entrypoint` — the docker equivalent of a javascript action's `runs.pre`/`runs.post`. Neither key existed on `ActionRuns`, so the YAML decoder dropped them and docker actions silently skipped their setup and cleanup stages.

Only the entrypoint is stage specific. [`ContainerActionHandler`](https://github.com/actions/runner/blob/main/src/Runner.Worker/Handlers/ContainerActionHandler.cs) selects `Data.Pre`/`Data.Post` per stage but evaluates `runs.args` and `runs.env` unconditionally, so `docker create` receives the action's args and env on every stage. The `entrypoint` input stays main only, because it is read inside the main branch.

The stage is carried as the existing `stepStage` value rather than a separate parameter, and the pre and post stages reuse the action path resolution that `runPreStep`/`runPostStep` already open-coded three times, so the diff also drops those copies.

Known gap: `stepActionLocal.pre()` is a no-op for every `using`, so `pre-entrypoint` does not run for `uses: ./local-action` while `post-entrypoint` does. Closing it requires reading the action model before the main stage and adding a pre case to `getIfExpression` for `pre-if`, which also changes local node, go and composite actions — better as its own change.

---------

Co-authored-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-authored-by: silverwind <me@silverwind.io>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1106
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-authored-by: bircni <bircni@icloud.com>

act/model/action.go

@@ -84,7 +84,9 @@ type ActionRuns struct {
 	Post           string            `yaml:"post"`
 	PostIf         string            `yaml:"post-if"`
 	Image          string            `yaml:"image"`
+	PreEntrypoint  string            `yaml:"pre-entrypoint"`
 	Entrypoint     string            `yaml:"entrypoint"`
+	PostEntrypoint string            `yaml:"post-entrypoint"`
 	Args           []string          `yaml:"args"`
 	Steps          []Step            `yaml:"steps"`
 }

act/model/action_test.go

@@ -61,3 +61,22 @@ runs:
 		t.Fatalf("error = %q, want invalid value", err)
 	}
 }
+
+func TestReadActionDockerEntrypoints(t *testing.T) {
+	action, err := ReadAction(strings.NewReader(`
+runs:
+  using: docker
+  image: Dockerfile
+  pre-entrypoint: pre.sh
+  post-entrypoint: post.sh
+`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if action.Runs.PreEntrypoint != "pre.sh" {
+		t.Fatalf("pre-entrypoint = %q, want pre.sh", action.Runs.PreEntrypoint)
+	}
+	if action.Runs.PostEntrypoint != "post.sh" {
+		t.Fatalf("post-entrypoint = %q, want post.sh", action.Runs.PostEntrypoint)
+	}
+}

act/runner/action.go

@@ -207,7 +207,7 @@ func runActionImpl(step actionStep, actionDir string, remoteAction *remoteAction
 			if remoteAction == nil {
 				location = containerActionDir
 			}
-			return execAsDocker(ctx, step, actionName, actionDir, location, remoteAction == nil)
+			return execAsDocker(ctx, step, actionName, actionDir, location, remoteAction == nil, stepStageMain)
 		case x.IsComposite():
 			if err := maybeCopyToActionDir(ctx, step, actionDir, actionPath, containerActionDir); err != nil {
 				return err
@@ -305,7 +305,7 @@ func dockerActionImageTag(repository, actionName string, localAction bool) strin
 }
 
 // TODO: break out parts of function to reduce complexicity
-func execAsDocker(ctx context.Context, step actionStep, actionName, actionDir, basedir string, localAction bool) error {
+func execAsDocker(ctx context.Context, step actionStep, actionName, actionDir, basedir string, localAction bool, stage stepStage) error {
 	logger := common.Logger(ctx)
 	rc := step.getRunContext()
 	action := step.getActionModel()
@@ -386,17 +386,10 @@ func execAsDocker(ctx context.Context, step actionStep, actionName, actionDir, b
 		cmd = action.Runs.Args
 		evalDockerArgs(ctx, step, action, &cmd)
 	}
-	entrypoint := strings.Fields(eval.Interpolate(ctx, step.getStepModel().With["entrypoint"]))
+	entrypoint, err := dockerEntrypoint(ctx, step, eval, stage)
-	if len(entrypoint) == 0 {
-		if action.Runs.Entrypoint != "" {
-			entrypoint, err = shellquote.Split(action.Runs.Entrypoint)
 	if err != nil {
 		return err
 	}
-		} else {
-			entrypoint = nil
-		}
-	}
 	stepContainer := newStepContainer(ctx, step, image, cmd, entrypoint)
 	return common.NewPipelineExecutor(
 		prepImage,
@@ -409,6 +402,30 @@ func execAsDocker(ctx context.Context, step actionStep, actionName, actionDir, b
 	).Finally(stepContainer.Close())(ctx)
 }
 
+// dockerEntrypoint returns the entrypoint the action's image runs with for the given
+// stage. Only the main stage honours the `entrypoint` input.
+func dockerEntrypoint(ctx context.Context, step actionStep, eval ExpressionEvaluator, stage stepStage) ([]string, error) {
+	runs := step.getActionModel().Runs
+
+	var entrypoint string
+	switch stage {
+	case stepStagePre:
+		entrypoint = runs.PreEntrypoint
+	case stepStagePost:
+		entrypoint = runs.PostEntrypoint
+	default:
+		if fields := strings.Fields(eval.Interpolate(ctx, step.getStepModel().With["entrypoint"])); len(fields) > 0 {
+			return fields, nil
+		}
+		entrypoint = runs.Entrypoint
+	}
+
+	if entrypoint == "" {
+		return nil, nil
+	}
+	return shellquote.Split(entrypoint)
+}
+
 func evalDockerArgs(ctx context.Context, step step, action *model.Action, cmd *[]string) {
 	rc := step.getRunContext()
 	stepModel := step.getStepModel()
@@ -559,44 +576,57 @@ func hasPreStep(step actionStep) common.Conditional {
 		return action.Runs.Using.IsComposite() ||
 			(action.Runs.Using.IsNode() &&
 				action.Runs.Pre != "") ||
+			(action.Runs.Using.IsDocker() &&
+				action.Runs.PreEntrypoint != "") ||
 			(action.Runs.Using == model.ActionRunsUsingGo &&
 				action.Runs.Pre != "")
 	}
 }
 
+// actionStagePaths resolves where a step's action lives and where the job container sees
+// it, for the pre and post stage.
+func actionStagePaths(step actionStep) (actionDir, actionPath, actionName, containerActionDir string) {
+	rc := step.getRunContext()
+	stepModel := step.getStepModel()
+
+	if _, ok := step.(*stepActionRemote); ok {
+		actionDir = fmt.Sprintf("%s/%s", rc.ActionCacheDir(), stepModel.UsesHash())
+		actionPath = newRemoteAction(stepModel.Uses).Path
+	} else {
+		actionDir = filepath.Join(rc.Config.Workdir, stepModel.Uses)
+	}
+
+	actionName, containerActionDir = getContainerActionPaths(stepModel, path.Join(actionDir, actionPath), rc)
+	return actionDir, actionPath, actionName, containerActionDir
+}
+
+// execDockerActionStage runs a docker action's image for its pre or post stage.
+func execDockerActionStage(ctx context.Context, step actionStep, stage stepStage) error {
+	actionDir, actionPath, actionName, containerActionDir := actionStagePaths(step)
+
+	_, remote := step.(*stepActionRemote)
+	location := containerActionDir
+	if remote {
+		location = path.Join(actionDir, actionPath)
+	}
+	return execAsDocker(ctx, step, actionName, actionDir, location, !remote, stage)
+}
+
 func runPreStep(step actionStep) common.Executor {
 	return func(ctx context.Context) error {
 		logger := common.Logger(ctx)
 		logger.Debugf("run pre step for '%s'", step.getStepModel())
 
 		rc := step.getRunContext()
-		stepModel := step.getStepModel()
 		action := step.getActionModel()
 
+		actionDir, actionPath, _, containerActionDir := actionStagePaths(step)
+
 		x := action.Runs.Using
 		switch {
 		case x.IsNode():
 			// defaults in pre steps were missing, however provided inputs are available
 			populateEnvsFromInput(ctx, step.getEnv(), action, rc)
-			// todo: refactor into step
-			var actionDir string
-			var actionPath string
-			if _, ok := step.(*stepActionRemote); ok {
-				actionPath = newRemoteAction(stepModel.Uses).Path
-				actionDir = fmt.Sprintf("%s/%s", rc.ActionCacheDir(), stepModel.UsesHash())
-			} else {
-				actionDir = filepath.Join(rc.Config.Workdir, stepModel.Uses)
-				actionPath = ""
-			}
-
-			var actionLocation string
-			if actionPath != "" {
-				actionLocation = path.Join(actionDir, actionPath)
-			} else {
-				actionLocation = actionDir
-			}
-
-			_, containerActionDir := getContainerActionPaths(stepModel, actionLocation, rc)
 
 			if err := maybeCopyToActionDir(ctx, step, actionDir, actionPath, containerActionDir); err != nil {
 				return err
@@ -609,6 +639,12 @@ func runPreStep(step actionStep) common.Executor {
 
 			return rc.execJobContainer(containerArgs, *step.getEnv(), "", "")(ctx)
 
+		case x.IsDocker():
+			// defaults in pre steps were missing, however provided inputs are available
+			populateEnvsFromInput(ctx, step.getEnv(), action, rc)
+
+			return execDockerActionStage(ctx, step, stepStagePre)
+
 		case x.IsComposite():
 			if step.getCompositeSteps() == nil {
 				step.getCompositeRunContext(ctx)
@@ -622,25 +658,6 @@ func runPreStep(step actionStep) common.Executor {
 		case x == model.ActionRunsUsingGo:
 			// defaults in pre steps were missing, however provided inputs are available
 			populateEnvsFromInput(ctx, step.getEnv(), action, rc)
-			// todo: refactor into step
-			var actionDir string
-			var actionPath string
-			if _, ok := step.(*stepActionRemote); ok {
-				actionPath = newRemoteAction(stepModel.Uses).Path
-				actionDir = fmt.Sprintf("%s/%s", rc.ActionCacheDir(), stepModel.UsesHash())
-			} else {
-				actionDir = filepath.Join(rc.Config.Workdir, stepModel.Uses)
-				actionPath = ""
-			}
-
-			var actionLocation string
-			if actionPath != "" {
-				actionLocation = path.Join(actionDir, actionPath)
-			} else {
-				actionLocation = actionDir
-			}
-
-			_, containerActionDir := getContainerActionPaths(stepModel, actionLocation, rc)
 
 			if err := maybeCopyToActionDir(ctx, step, actionDir, actionPath, containerActionDir); err != nil {
 				return err
@@ -693,6 +710,8 @@ func hasPostStep(step actionStep) common.Conditional {
 		return action.Runs.Using.IsComposite() ||
 			(action.Runs.Using.IsNode() &&
 				action.Runs.Post != "") ||
+			(action.Runs.Using.IsDocker() &&
+				action.Runs.PostEntrypoint != "") ||
 			(action.Runs.Using == model.ActionRunsUsingGo &&
 				action.Runs.Post != "")
 	}
@@ -704,28 +723,9 @@ func runPostStep(step actionStep) common.Executor {
 		logger.Debugf("run post step for '%s'", step.getStepModel())
 
 		rc := step.getRunContext()
-		stepModel := step.getStepModel()
 		action := step.getActionModel()
 
-		// todo: refactor into step
+		actionDir, actionPath, _, containerActionDir := actionStagePaths(step)
-		var actionDir string
-		var actionPath string
-		if _, ok := step.(*stepActionRemote); ok {
-			actionPath = newRemoteAction(stepModel.Uses).Path
-			actionDir = fmt.Sprintf("%s/%s", rc.ActionCacheDir(), stepModel.UsesHash())
-		} else {
-			actionDir = filepath.Join(rc.Config.Workdir, stepModel.Uses)
-			actionPath = ""
-		}
-
-		var actionLocation string
-		if actionPath != "" {
-			actionLocation = path.Join(actionDir, actionPath)
-		} else {
-			actionLocation = actionDir
-		}
-
-		_, containerActionDir := getContainerActionPaths(stepModel, actionLocation, rc)
 
 		x := action.Runs.Using
 		switch {
@@ -740,6 +740,11 @@ func runPostStep(step actionStep) common.Executor {
 
 			return rc.execJobContainer(containerArgs, *step.getEnv(), "", "")(ctx)
 
+		case x.IsDocker():
+			populateEnvsFromSavedState(step.getEnv(), step, rc)
+
+			return execDockerActionStage(ctx, step, stepStagePost)
+
 		case x.IsComposite():
 			if err := maybeCopyToActionDir(ctx, step, actionDir, actionPath, containerActionDir); err != nil {
 				return err

act/runner/action_test.go

@@ -183,7 +183,7 @@ func TestExecAsDockerAutoRemove(t *testing.T) {
 		cm.On("Start", true).Return(func(context.Context) error { return nil })
 		cm.On("Close").Return(func(context.Context) error { return nil })
 
-		require.NoError(t, execAsDocker(context.Background(), step, "action", t.TempDir(), t.TempDir(), false))
+		require.NoError(t, execAsDocker(context.Background(), step, "action", t.TempDir(), t.TempDir(), false, stepStageMain))
 		cm.AssertExpectations(t)
 		assert.Equal(t, tc.removes, removes)
 	}
@@ -465,7 +465,7 @@ func TestExecAsDockerHoldsCloneLockForRemoteUncached(t *testing.T) {
 	defer cancel()
 
 	done := make(chan error, 1)
-	go func() { done <- execAsDocker(ctx, step, "test-action", actionDir, actionDir, false) }()
+	go func() { done <- execAsDocker(ctx, step, "test-action", actionDir, actionDir, false, stepStageMain) }()
 
 	select {
 	case <-innerEntered:
@@ -541,3 +541,86 @@ func TestDockerActionImageTag(t *testing.T) {
 		dockerActionImageTag("owner/repo", "./sub", true),
 	)
 }
+
+// Only the entrypoint is stage specific: every stage of a docker action receives runs.args
+// and runs.env, and the `entrypoint` input applies to the main stage alone.
+func TestExecAsDockerStageEntrypoint(t *testing.T) {
+	orig := ContainerNewContainer
+	defer func() { ContainerNewContainer = orig }()
+
+	for _, tc := range []struct {
+		name           string
+		stage          stepStage
+		wantEntrypoint []string
+	}{
+		{
+			name:           "main stage prefers the entrypoint input",
+			stage:          stepStageMain,
+			wantEntrypoint: []string{"input.sh"},
+		},
+		{
+			name:           "pre stage uses runs.pre-entrypoint",
+			stage:          stepStagePre,
+			wantEntrypoint: []string{"pre.sh", "--verbose"},
+		},
+		{
+			name:           "post stage uses runs.post-entrypoint",
+			stage:          stepStagePost,
+			wantEntrypoint: []string{"post.sh"},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			cm := &containerMock{}
+			var input *container.NewContainerInput
+			ContainerNewContainer = func(in *container.NewContainerInput) container.ExecutionsEnvironment {
+				input = in
+				return cm
+			}
+
+			step := &stepActionRemote{
+				Step: &model.Step{ID: "1", Uses: "org/action@v1", With: map[string]string{"entrypoint": "input.sh"}},
+				RunContext: &RunContext{
+					Config:       &Config{},
+					Run:          &model.Run{JobID: "1", Workflow: &model.Workflow{Jobs: map[string]*model.Job{"1": {}}}},
+					JobContainer: cm,
+				},
+				action: &model.Action{Runs: model.ActionRuns{
+					Using:          "docker",
+					Image:          "docker://node:14",
+					PreEntrypoint:  "pre.sh --verbose",
+					Entrypoint:     "main.sh",
+					PostEntrypoint: "post.sh",
+					Args:           []string{"hello"},
+					Env:            map[string]string{"MY_VAR": "world"},
+				}},
+				env: map[string]string{},
+			}
+
+			cm.On("Pull", false).Return(func(context.Context) error { return nil })
+			cm.On("Remove").Return(func(context.Context) error { return nil })
+			cm.On("Create", []string(nil), []string(nil)).Return(func(context.Context) error { return nil })
+			cm.On("Start", true).Return(func(context.Context) error { return nil })
+			cm.On("Close").Return(func(context.Context) error { return nil })
+
+			require.NoError(t, execAsDocker(context.Background(), step, "action", t.TempDir(), t.TempDir(), false, tc.stage))
+			require.NotNil(t, input)
+			assert.Equal(t, tc.wantEntrypoint, input.Entrypoint)
+			assert.Equal(t, []string{"hello"}, input.Cmd)
+			assert.Contains(t, input.Env, "MY_VAR=world")
+		})
+	}
+}
+
+func TestDockerActionHasPreAndPostStep(t *testing.T) {
+	newStep := func(runs model.ActionRuns) actionStep {
+		return &stepActionRemote{action: &model.Action{Runs: runs}}
+	}
+	ctx := context.Background()
+
+	assert.False(t, hasPreStep(newStep(model.ActionRuns{Using: "docker", Image: "Dockerfile"}))(ctx))
+	assert.False(t, hasPostStep(newStep(model.ActionRuns{Using: "docker", Image: "Dockerfile"}))(ctx))
+
+	withStages := model.ActionRuns{Using: "docker", Image: "Dockerfile", PreEntrypoint: "pre.sh", PostEntrypoint: "post.sh"}
+	assert.True(t, hasPreStep(newStep(withStages))(ctx))
+	assert.True(t, hasPostStep(newStep(withStages))(ctx))
+}