Handle Dockerfile action manifest

Avoid erroring when an action used by a project has a `Dockerfile`
manifest. Also update related documentation.

Author: ericcornelissen

CHANGELOG.md

@@ -12,6 +12,12 @@ Versioning].
 
 ## [Unreleased]
 
+### Bugs
+
+- Fix errors for actions with a `Dockerfile` manifest.
+
+## [v0.5.0] - 2025-05-03
+
 ### Enhancements
 
 - Correct typo in the `ghasum help verify` output.

README.md

@@ -59,12 +59,15 @@ recommended to use commit SHAs instead to avoid failing verification by ghasum.
 
 - Requires manual intervention when an Action is updated.
 - The hashing algorithm used for checksums is not configurable.
-- Checksums do not provide protection against [unpinnable actions].[^1] 
+- `ghasum` does not (yet, [#216]) handle Docker-based [unpinnable actions].
+- Checksums do not provide protection against code-based [unpinnable actions].
 
-[^1]: See [github/roadmap#592] for work on unpinnable actions by GitHub.
+Some of these limitations may be addressed by Github's Immutable Actions
+initiative, see [github/roadmap#592] for more information.
 
-[unpinnable actions]: https://www.paloaltonetworks.com/blog/prisma-cloud/unpinnable-actions-github-security/
+[#216]:https://github.com/chains-project/ghasum/issues/216
 [github/roadmap#592]: https://github.com/github/roadmap/issues/592
+[unpinnable actions]: https://www.paloaltonetworks.com/blog/prisma-cloud/unpinnable-actions-github-security/
 
 ## Background
 

SPECIFICATION.md

@@ -203,8 +203,7 @@ version 1
 
 ## Definitions
 
-- _action manifest_ is the file `action.yml` or `action.yaml` (mutually
-  exclusive).
+- _action manifest_ is the file `action.yml`, `action.yaml` or `Dockerfile`.
 - _checksum file_ is the file `.github/workflows/gha.sum`.
 - _workflows directory_ is the directory `.github/workflows`.
 

internal/gha/actions.go

@@ -142,14 +142,21 @@ func workflowInRepo(repo fs.FS, path string) ([]byte, error) {
 
 func manifestInRepo(repo fs.FS, dir string) ([]byte, error) {
 	path := filepath.Join(dir, "action.yml")
-	file, err := repo.Open(path)
-	if err != nil {
-		path = filepath.Join(dir, "action.yaml")
-		if file, err = repo.Open(path); err != nil {
-			return nil, fmt.Errorf("could not open manifest (action.yml or action.yaml) at %s: %v", dir, err)
-		}
+	if file, err := repo.Open(path); err == nil {
+		data, _ := io.ReadAll(file)
+		return data, nil
 	}
 
-	data, _ := io.ReadAll(file)
-	return data, nil
+	path = filepath.Join(dir, "action.yaml")
+	if file, err := repo.Open(path); err == nil {
+		data, _ := io.ReadAll(file)
+		return data, nil
+	}
+
+	path = filepath.Join(dir, "Dockerfile")
+	if _, err := repo.Open(path); err == nil {
+		return nil, ErrDockerfileManifest
+	}
+
+	return nil, ErrNoManifest
 }

internal/gha/actions_test.go

@@ -16,6 +16,7 @@ package gha
 
 import (
 	"bytes"
+	"errors"
 	"testing"
 	"testing/quick"
 
@@ -702,7 +703,7 @@ func TestManifestInRepo(t *testing.T) {
 		type TestCase struct {
 			fs   map[string]mockFsEntry
 			dir  string
-			want []byte
+			want error
 		}
 
 		testCases := map[string]TestCase{
@@ -713,7 +714,7 @@ func TestManifestInRepo(t *testing.T) {
 					},
 				},
 				dir:  "nested",
-				want: []byte(manifestWithStep),
+				want: ErrNoManifest,
 			},
 			".yaml manifest in different dir": {
 				fs: map[string]mockFsEntry{
@@ -722,17 +723,36 @@ func TestManifestInRepo(t *testing.T) {
 					},
 				},
 				dir:  "nested",
-				want: []byte(manifestWithStep),
+				want: ErrNoManifest,
+			},
+			"Dockerfile manifest": {
+				fs: map[string]mockFsEntry{
+					"Dockerfile": {
+						Content: []byte(manifestDockerfile),
+					},
+				},
+				dir:  "",
+				want: ErrDockerfileManifest,
 			},
 		}
 
 		for name, tt := range testCases {
 			t.Run(name, func(t *testing.T) {
 				t.Parallel()
 
-				if _, err := mockRepo(tt.fs); err != nil {
+				repo, err := mockRepo(tt.fs)
+				if err != nil {
+					t.Fatalf("Could not initialize file system: %+v", err)
+				}
+
+				_, err = manifestInRepo(repo, tt.dir)
+				if err == nil {
 					t.Fatal("Unexpected success")
 				}
+
+				if got, want := err, tt.want; !errors.Is(got, want) {
+					t.Errorf("Unexpected error (got %q, want %q)", got, want)
+				}
 			})
 		}
 	})

internal/gha/errors.go

@@ -22,4 +22,7 @@ var (
 	ErrInvalidUsesRepo = errors.New("invalid repository in uses")
 	ErrInvalidUsesPath = errors.New("invalid repository path in uses")
 	ErrLocalAction     = errors.New("uses is a local action")
+
+	ErrDockerfileManifest = errors.New("found a Dockerfile manifest")
+	ErrNoManifest         = errors.New("could not find a manifest")
 )

internal/gha/gha.go

@@ -15,6 +15,7 @@
 package gha
 
 import (
+	"errors"
 	"fmt"
 	"io/fs"
 	"path/filepath"
@@ -147,7 +148,9 @@ func JobActions(repo fs.FS, path, name string) ([]GitHubAction, error) {
 // specified directory in the given file system hierarchy.
 func ManifestActions(repo fs.FS, path string) ([]GitHubAction, error) {
 	data, err := manifestInRepo(repo, path)
-	if err != nil {
+	if errors.Is(err, ErrDockerfileManifest) {
+		return nil, nil
+	} else if err != nil {
 		return nil, err
 	}
 

internal/gha/gha_test.go

@@ -667,8 +667,8 @@ func TestManifestActions(t *testing.T) {
 		wantErr bool
 	}
 
-	testCases := []TestCase{
-		{
+	testCases := map[string]TestCase{
+		"root manifest without transitive actions": {
 			fs: map[string]mockFsEntry{
 				"action.yml": {
 					Content: []byte(manifestWithNoSteps),
@@ -677,7 +677,7 @@ func TestManifestActions(t *testing.T) {
 			path:    "",
 			wantErr: false,
 		},
-		{
+		"root manifest with transitive actions": {
 			fs: map[string]mockFsEntry{
 				"action.yml": {
 					Content: []byte(manifestWithStep),
@@ -686,7 +686,7 @@ func TestManifestActions(t *testing.T) {
 			path:    "",
 			wantErr: false,
 		},
-		{
+		"root manifest using nested actions": {
 			fs: map[string]mockFsEntry{
 				"action.yml": {
 					Content: []byte(manifestWithNestedActions),
@@ -695,7 +695,7 @@ func TestManifestActions(t *testing.T) {
 			path:    "",
 			wantErr: false,
 		},
-		{
+		"nested .yml manifest": {
 			fs: map[string]mockFsEntry{
 				"nested": {
 					Dir: true,
@@ -709,7 +709,7 @@ func TestManifestActions(t *testing.T) {
 			path:    "nested",
 			wantErr: false,
 		},
-		{
+		"root .yaml manifest": {
 			fs: map[string]mockFsEntry{
 				"action.yaml": {
 					Content: []byte(manifestWithStep),
@@ -718,7 +718,7 @@ func TestManifestActions(t *testing.T) {
 			path:    "",
 			wantErr: false,
 		},
-		{
+		"nested .yaml manifest": {
 			fs: map[string]mockFsEntry{
 				"nested": {
 					Dir: true,
@@ -732,7 +732,30 @@ func TestManifestActions(t *testing.T) {
 			path:    "nested",
 			wantErr: false,
 		},
-		{
+		"root Dockerfile manifest": {
+			fs: map[string]mockFsEntry{
+				"Dockerfile": {
+					Content: []byte(manifestDockerfile),
+				},
+			},
+			path:    "",
+			wantErr: false,
+		},
+		"nested Dockerfile manifest": {
+			fs: map[string]mockFsEntry{
+				"nested": {
+					Dir: true,
+					Children: map[string]mockFsEntry{
+						"Dockerfile": {
+							Content: []byte(manifestDockerfile),
+						},
+					},
+				},
+			},
+			path:    "nested",
+			wantErr: false,
+		},
+		"manifest with syntax error": {
 			fs: map[string]mockFsEntry{
 				"action.yml": {
 					Content: []byte(yamlWithSyntaxError),
@@ -741,7 +764,7 @@ func TestManifestActions(t *testing.T) {
 			path:    "",
 			wantErr: true,
 		},
-		{
+		"manifest with invalid uses value": {
 			fs: map[string]mockFsEntry{
 				"action.yml": {
 					Content: []byte(manifestWithInvalidUses),
@@ -750,15 +773,15 @@ func TestManifestActions(t *testing.T) {
 			path:    "",
 			wantErr: true,
 		},
-		{
+		"empty repo": {
 			fs:      map[string]mockFsEntry{},
 			path:    "",
 			wantErr: true,
 		},
 	}
 
-	for i, tt := range testCases {
-		t.Run(fmt.Sprintf("#%d", i), func(t *testing.T) {
+	for name, tt := range testCases {
+		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 
 			repo, err := mockRepo(tt.fs)

internal/gha/shared_test.go

@@ -51,6 +51,9 @@ runs:
 runs:
   steps:
     - uses: this-is-not-an-action
+`
+	manifestDockerfile = `FROM docker.io/alpine:3.21.3
+ENTRYPOINT ["echo", "Hello world!"]
 `
 
 	workflowWithNoJobs = `name: workflow with no jobs