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

@@ -76,17 +76,19 @@ func (a ActionRunsUsing) IsComposite() bool {
 
 // ActionRuns are a field in Action
 type ActionRuns struct {
-	Using      ActionRunsUsing   `yaml:"using"`
-	Env        map[string]string `yaml:"env"`
-	Main       string            `yaml:"main"`
-	Pre        string            `yaml:"pre"`
-	PreIf      string            `yaml:"pre-if"`
-	Post       string            `yaml:"post"`
-	PostIf     string            `yaml:"post-if"`
-	Image      string            `yaml:"image"`
-	Entrypoint string            `yaml:"entrypoint"`
-	Args       []string          `yaml:"args"`
-	Steps      []Step            `yaml:"steps"`
+	Using          ActionRunsUsing   `yaml:"using"`
+	Env            map[string]string `yaml:"env"`
+	Main           string            `yaml:"main"`
+	Pre            string            `yaml:"pre"`
+	PreIf          string            `yaml:"pre-if"`
+	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"`
 }
 
 // Action describes a metadata file for GitHub actions. The metadata filename must be either action.yml or action.yaml. The data in the metadata file defines the inputs, outputs and main entrypoint for your action.

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()
@@ -386,16 +386,9 @@ 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"]))
-	if len(entrypoint) == 0 {
-		if action.Runs.Entrypoint != "" {
-			entrypoint, err = shellquote.Split(action.Runs.Entrypoint)
-			if err != nil {
-				return err
-			}
-		} else {
-			entrypoint = nil
-		}
+	entrypoint, err := dockerEntrypoint(ctx, step, eval, stage)
+	if err != nil {
+		return err
 	}
 	stepContainer := newStepContainer(ctx, step, image, cmd, entrypoint)
 	return common.NewPipelineExecutor(
@@ -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
-		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)
+		actionDir, actionPath, _, containerActionDir := actionStagePaths(step)
 
 		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))
+}

act/runner/expression.go

@@ -95,9 +95,7 @@ func (rc *RunContext) NewExpressionEvaluatorWithEnv(ctx context.Context, env map
 		Inputs:    inputs,
 		HashFiles: getHashFilesFunction(ctx, rc),
 	}
-	if rc.JobContainer != nil {
-		ee.Runner = rc.JobContainer.GetRunnerContext(ctx)
-	}
+	ee.Runner = rc.getRunnerContext(ctx)
 	return expressionEvaluator{
 		interpreter: exprparser.NewInterpeter(ee, exprparser.Config{
 			Run:        rc.Run,
@@ -149,9 +147,7 @@ func (rc *RunContext) NewStepExpressionEvaluator(ctx context.Context, step step)
 		Inputs:    inputs,
 		HashFiles: getHashFilesFunction(ctx, rc),
 	}
-	if rc.JobContainer != nil {
-		ee.Runner = rc.JobContainer.GetRunnerContext(ctx)
-	}
+	ee.Runner = rc.getRunnerContext(ctx)
 	return expressionEvaluator{
 		interpreter: exprparser.NewInterpeter(ee, exprparser.Config{
 			Run:        rc.Run,

act/runner/run_context.go

@@ -298,7 +298,7 @@ func (rc *RunContext) startHostEnvironment() common.Executor {
 			AllocatePTY: rc.Config.AllocatePTY,
 		}
 		rc.cleanUpJobContainer = rc.JobContainer.Remove()
-		for k, v := range rc.JobContainer.GetRunnerContext(ctx) {
+		for k, v := range rc.getRunnerContext(ctx) {
 			if v, ok := v.(string); ok {
 				rc.Env["RUNNER_"+strings.ToUpper(k)] = v
 			}
@@ -986,6 +986,21 @@ func (rc *RunContext) getStepsContext() map[string]*model.StepResult {
 	return rc.StepResults
 }
 
+// getRunnerContext returns the `runner` context: what the execution environment knows
+// (os, arch, temp, tool_cache) plus what only the runner process knows.
+func (rc *RunContext) getRunnerContext(ctx context.Context) map[string]any {
+	runnerContext := map[string]any{}
+	if rc.JobContainer != nil {
+		maps0.Copy(runnerContext, rc.JobContainer.GetRunnerContext(ctx))
+	}
+	runnerContext["name"] = rc.Config.RunnerName
+	runnerContext["environment"] = "self-hosted"
+	if rc.Config.RunnerDebug() {
+		runnerContext["debug"] = "1"
+	}
+	return runnerContext
+}
+
 func (rc *RunContext) getGithubContext(ctx context.Context) *model.GithubContext {
 	logger := common.Logger(ctx)
 	ghc := &model.GithubContext{
@@ -1170,7 +1185,7 @@ func nestedMapLookup(m map[string]any, ks ...string) (rval any) {
 	}
 }
 
-func (rc *RunContext) withGithubEnv(ctx context.Context, github *model.GithubContext, env map[string]string) map[string]string { //nolint:unparam // pre-existing issue from nektos/act
+func (rc *RunContext) withGithubEnv(ctx context.Context, github *model.GithubContext, env map[string]string) {
 	env["CI"] = "true"
 	env["GITHUB_WORKFLOW"] = github.Workflow
 	env["GITHUB_RUN_ID"] = github.RunID
@@ -1212,23 +1227,71 @@ func (rc *RunContext) withGithubEnv(ctx context.Context, github *model.GithubCon
 		env["GITHUB_RUN_ATTEMPT"] = github.RunAttempt
 	}
 
+	env["RUNNER_NAME"] = rc.Config.RunnerName
+	env["RUNNER_ENVIRONMENT"] = "self-hosted"
+	if workspace := parentDir(github.Workspace); workspace != "" {
+		env["RUNNER_WORKSPACE"] = workspace
+	}
+	if rc.Config.RunnerDebug() {
+		env["RUNNER_DEBUG"] = "1"
+	}
+
 	if rc.Config.ArtifactServerPath != "" {
 		setActionRuntimeVars(rc, env)
 	}
 
-	for _, platformName := range rc.runsOnPlatformNames(ctx) {
-		if platformName != "" {
-			if platformName == "ubuntu-latest" {
-				// hardcode current ubuntu-latest since we have no way to check that 'on the fly'
-				env["ImageOS"] = "ubuntu20"
-			} else {
-				platformName = strings.SplitN(strings.Replace(platformName, `-`, ``, 1), `.`, 2)[0]
-				env["ImageOS"] = platformName
-			}
-		}
+	if imageOS := rc.imageOS(ctx); imageOS != "" {
+		env["ImageOS"] = imageOS
+	}
+}
+
+// parentDir returns the directory containing p, or "" when p names no parent. Both
+// separators are accepted rather than filepath's, as p may describe a container while
+// the runner itself runs on Windows, or the other way round.
+func parentDir(p string) string {
+	if slash := strings.LastIndexAny(p, `/\`); slash > 0 {
+		return p[:slash]
+	}
+	return ""
+}
+
+// imageOS returns ImageOS, which setup-* actions use to tell one runner image release
+// from another. The resolved image tag is preferred over the runs-on label because it
+// still names a release when the label is a rolling one such as ubuntu-latest.
+func (rc *RunContext) imageOS(ctx context.Context) string {
+	if rc.Run.Job().RunsOn() == nil {
+		// A composite action runs on a synthetic job, and resolving its image would only
+		// log that runs-on is missing.
+		return ""
+	}
+	if imageOS := imageOSFromImage(rc.platformImage(ctx)); imageOS != "" {
+		return imageOS
 	}
 
-	return env
+	for _, platformName := range slices.Backward(rc.runsOnPlatformNames(ctx)) {
+		if platformName == "ubuntu-latest" {
+			// Rolling label whose image names no release either, so keep the historical value.
+			return "ubuntu20"
+		} else if platformName != "" {
+			return strings.SplitN(strings.Replace(platformName, `-`, ``, 1), `.`, 2)[0]
+		}
+	}
+	return ""
+}
+
+// imageOSTag matches an image reference tagged with an OS family ImageOS can report plus
+// its release, such as "docker.gitea.com/runner-images:ubuntu-24.04". Anything else
+// ("ubuntu-latest", "app:22.04", "catthehacker/ubuntu:act-22.04", or a registry port) is
+// left to the runs-on label rather than turned into a bogus OS.
+var imageOSTag = regexp.MustCompile(`:(ubuntu|win|macos)-?([0-9]+)[^/]*$`)
+
+// imageOSFromImage derives ImageOS from an image reference, e.g.
+// "docker.gitea.com/runner-images:ubuntu-24.04" yields "ubuntu24".
+func imageOSFromImage(image string) string {
+	if match := imageOSTag.FindStringSubmatch(image); match != nil {
+		return match[1] + match[2]
+	}
+	return ""
 }
 
 func setActionRuntimeVars(rc *RunContext, env map[string]string) {

act/runner/run_context_test.go

@@ -940,3 +940,117 @@ func TestRunContext_cleanupFailedStart(t *testing.T) {
 		assert.NotPanics(t, func() { (&RunContext{}).cleanupFailedStart(context.Background()) })
 	})
 }
+
+func TestImageOSFromImage(t *testing.T) {
+	for _, tc := range []struct {
+		image string
+		want  string
+	}{
+		{"", ""},
+		{"docker.gitea.com/runner-images:ubuntu-24.04", "ubuntu24"},
+		{"docker.gitea.com/runner-images:ubuntu-latest", ""},
+		{"runner-images:ubuntu22.04", "ubuntu22"},
+		{"node:20", ""},
+		{"ubuntu:22.04", ""},
+		{"ubuntu", ""},
+		{"catthehacker/ubuntu:act-22.04", ""},
+		{"myco/ubuntu:v2.1", ""},
+		{"myco/ubuntu:v22.04", ""},
+		{"app:release-1", ""},
+		{"app:1.2.3", ""},
+		{"app:build-2.1", ""},
+		{"registry.example.com:5000/runner-images", ""},
+		{"registry.example.com:5000/runner-images:ubuntu-24.04", "ubuntu24"},
+	} {
+		t.Run(tc.image, func(t *testing.T) {
+			assert.Equal(t, tc.want, imageOSFromImage(tc.image))
+		})
+	}
+}
+
+func createRunsOnRunContext(t *testing.T, runsOn string) *RunContext {
+	return createIfTestRunContext(map[string]*model.Job{
+		"job1": createJob(t, "runs-on: "+runsOn, ""),
+	})
+}
+
+func TestRunContextImageOS(t *testing.T) {
+	ctx := context.Background()
+
+	t.Run("prefers the release in the resolved image tag", func(t *testing.T) {
+		rc := createRunsOnRunContext(t, "ubuntu-latest")
+		rc.Config.Platforms = map[string]string{
+			"ubuntu-latest": "docker.gitea.com/runner-images:ubuntu-24.04",
+		}
+		assert.Equal(t, "ubuntu24", rc.imageOS(ctx))
+	})
+
+	t.Run("falls back to the runs-on label", func(t *testing.T) {
+		rc := createRunsOnRunContext(t, "ubuntu-22.04")
+		rc.Config.Platforms = map[string]string{"ubuntu-22.04": "some-image"}
+		assert.Equal(t, "ubuntu22", rc.imageOS(ctx))
+	})
+
+	t.Run("keeps the historical value for a rolling label with no release", func(t *testing.T) {
+		assert.Equal(t, "ubuntu20", createRunsOnRunContext(t, "ubuntu-latest").imageOS(ctx))
+	})
+
+	t.Run("is empty for the synthetic job of a composite action", func(t *testing.T) {
+		rc := createIfTestRunContext(map[string]*model.Job{"job1": {}})
+		assert.Empty(t, rc.imageOS(ctx))
+	})
+}
+
+func TestRunContextGetRunnerContext(t *testing.T) {
+	ctx := context.Background()
+
+	t.Run("adds the runner values the container cannot know", func(t *testing.T) {
+		rc := createRunsOnRunContext(t, "ubuntu-latest")
+		rc.Config.RunnerName = "runner-1"
+
+		runnerContext := rc.getRunnerContext(ctx)
+		assert.Equal(t, "runner-1", runnerContext["name"])
+		assert.Equal(t, "self-hosted", runnerContext["environment"])
+		assert.NotContains(t, runnerContext, "debug")
+	})
+
+	t.Run("reports debug when step debugging is on", func(t *testing.T) {
+		rc := createRunsOnRunContext(t, "ubuntu-latest")
+		rc.Config.Secrets = map[string]string{"ACTIONS_STEP_DEBUG": "true"}
+
+		assert.Equal(t, "1", rc.getRunnerContext(ctx)["debug"])
+	})
+
+	t.Run("keeps the execution environment values", func(t *testing.T) {
+		rc := createRunsOnRunContext(t, "ubuntu-latest")
+		rc.JobContainer = &container.HostEnvironment{TmpDir: "/tmp/act", ToolCache: "/tmp/tool_cache"}
+
+		runnerContext := rc.getRunnerContext(ctx)
+		assert.Equal(t, "/tmp/act", runnerContext["temp"])
+		assert.Equal(t, "/tmp/tool_cache", runnerContext["tool_cache"])
+		assert.NotEmpty(t, runnerContext["os"])
+	})
+}
+
+func TestParentDir(t *testing.T) {
+	assert.Empty(t, parentDir(""))
+	assert.Empty(t, parentDir("repo"))
+	assert.Empty(t, parentDir("/repo"))
+	assert.Equal(t, "/workspace/owner", parentDir("/workspace/owner/repo"))
+	assert.Equal(t, `C:\workspace\owner`, parentDir(`C:\workspace\owner\repo`))
+}
+
+func TestRunContextWithGithubEnvRunnerValues(t *testing.T) {
+	ctx := context.Background()
+	rc := createRunsOnRunContext(t, "ubuntu-latest")
+	rc.Config.RunnerName = "runner-1"
+	rc.Config.Secrets = map[string]string{"ACTIONS_STEP_DEBUG": "true"}
+
+	env := map[string]string{}
+	rc.withGithubEnv(ctx, &model.GithubContext{Workspace: "/workspace/owner/repo"}, env)
+
+	assert.Equal(t, "runner-1", env["RUNNER_NAME"])
+	assert.Equal(t, "self-hosted", env["RUNNER_ENVIRONMENT"])
+	assert.Equal(t, "/workspace/owner", env["RUNNER_WORKSPACE"])
+	assert.Equal(t, "1", env["RUNNER_DEBUG"])
+}

act/runner/runner.go

@@ -92,6 +92,14 @@ type Config struct {
 	InsecureSkipTLS                   bool                         // whether to skip verifying TLS certificate of the Gitea instance
 	MaxParallel                       int                          // max parallel jobs to run across all workflows (0 = no limit, uses CPU count)
 	AllocatePTY                       bool                         // allocate a pseudo-TTY for each step's process
+	RunnerName                        string                       // name this runner registered with, reported as `runner.name`, defaults to the hostname
+}
+
+// RunnerDebug reports whether debug logging is on, exposed as `runner.debug` and
+// RUNNER_DEBUG. Only the secret also makes the reporter keep ::debug:: output, the env
+// is accepted for `exec` and for runners configured with it.
+func (c Config) RunnerDebug() bool {
+	return c.Secrets["ACTIONS_STEP_DEBUG"] == "true" || c.Env["ACTIONS_STEP_DEBUG"] == "true"
 }
 
 // GetToken: Adapt to Gitea
@@ -137,6 +145,11 @@ func New(runnerConfig *Config) (Runner, error) {
 }
 
 func (runner *runnerImpl) configure() (Runner, error) {
+	if runner.config.RunnerName == "" {
+		// Callers that do not register, such as `exec`, still get a `runner.name`.
+		runner.config.RunnerName, _ = os.Hostname()
+	}
+
 	runner.eventJSON = "{}"
 	if runner.config.EventJSON != "" {
 		runner.eventJSON = runner.config.EventJSON

act/runner/step_test.go

@@ -167,6 +167,9 @@ func TestSetupEnv(t *testing.T) {
 	delete((env), "GITHUB_REPOSITORY")
 	delete((env), "GITHUB_REPOSITORY_OWNER")
 	delete((env), "GITHUB_ACTOR")
+	// Host-dependent, asserted in TestRunContextWithGithubEnvRunnerValues instead.
+	delete((env), "RUNNER_NAME")
+	delete((env), "RUNNER_WORKSPACE")
 
 	assert.Equal(t, map[string]string{
 		"ACT":                      "true",
@@ -192,6 +195,7 @@ func TestSetupEnv(t *testing.T) {
 		"GITHUB_WORKFLOW":          "",
 		"INPUT_STEP_WITH":          "with-value",
 		"RC_KEY":                   "rcvalue",
+		"RUNNER_ENVIRONMENT":       "self-hosted",
 		"RUNNER_PERFLOG":           "/dev/null",
 		"RUNNER_TRACKING_ID":       "",
 	}, env)

internal/app/run/runner.go

@@ -474,6 +474,7 @@ func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.
 		Vars:                              task.Vars,
 		ValidVolumes:                      r.cfg.Container.ValidVolumes,
 		InsecureSkipTLS:                   r.cfg.Runner.Insecure,
+		RunnerName:                        r.name,
 	}
 
 	rr, err := runner.New(runnerConfig)