Dynamic artifact server port

cmd/input.go

@@ -43,7 +43,7 @@ type Input struct {
 	autoRemove                         bool
 	artifactServerPath                 string
 	artifactServerAddr                 string
-	artifactServerPort                 string
+	artifactServerPort                 uint16
 	noCacheServer                      bool
 	cacheServerPath                    string
 	cacheServerAddr                    string

cmd/root.go

@@ -90,7 +90,7 @@ func Execute(ctx context.Context, version string) {
 	rootCmd.PersistentFlags().StringVarP(&input.githubInstance, "github-instance", "", "github.com", "GitHub instance to use. Don't use this if you are not using GitHub Enterprise Server.")
 	rootCmd.PersistentFlags().StringVarP(&input.artifactServerPath, "artifact-server-path", "", "", "Defines the path where the artifact server stores uploads and retrieves downloads from. If not specified the artifact server will not start.")
 	rootCmd.PersistentFlags().StringVarP(&input.artifactServerAddr, "artifact-server-addr", "", common.GetOutboundIP().String(), "Defines the address to which the artifact server binds.")
-	rootCmd.PersistentFlags().StringVarP(&input.artifactServerPort, "artifact-server-port", "", "34567", "Defines the port where the artifact server listens.")
+	rootCmd.PersistentFlags().Uint16VarP(&input.artifactServerPort, "artifact-server-port", "", 0, "Defines the port where the artifact server listens. 0 means a randomly available port.")
 	rootCmd.PersistentFlags().BoolVarP(&input.noSkipCheckout, "no-skip-checkout", "", false, "Do not skip actions/checkout")
 	rootCmd.PersistentFlags().BoolVarP(&input.noCacheServer, "no-cache-server", "", false, "Disable cache server")
 	rootCmd.PersistentFlags().StringVarP(&input.cacheServerPath, "cache-server-path", "", filepath.Join(CacheHomeDir, "actcache"), "Defines the path where the cache server stores caches.")
@@ -592,7 +592,7 @@ func newRunCommand(ctx context.Context, input *Input) func(*cobra.Command, []str
 			return err
 		}
 
-		cancel := artifacts.Serve(ctx, input.artifactServerPath, input.artifactServerAddr, input.artifactServerPort)
+		cancel, artifactServer := artifacts.Serve(ctx, input.artifactServerPath, input.artifactServerAddr, input.artifactServerPort)
 
 		const cacheURLKey = "ACTIONS_CACHE_URL"
 		var cacheHandler *artifactcache.Handler
@@ -605,6 +605,17 @@ func newRunCommand(ctx context.Context, input *Input) func(*cobra.Command, []str
 			envs[cacheURLKey] = cacheHandler.ExternalURL() + "/"
 		}
 
+		const actionsRuntimeURLKey = "ACTIONS_RUNTIME_URL"
+		if !input.noCacheServer && envs[actionsRuntimeURLKey] == "" && artifactServer != nil {
+			envs[actionsRuntimeURLKey] = fmt.Sprintf("http://%s/", artifactServer.Addr)
+		}
+		const actionsRuntimeTokenKey = "ACTIONS_RUNTIME_TOKEN"
+		actionsRuntimeToken := os.Getenv(actionsRuntimeTokenKey)
+		if !input.noCacheServer && actionsRuntimeToken == "" && artifactServer != nil {
+			actionsRuntimeToken = "token"
+		}
+		envs[actionsRuntimeTokenKey] = actionsRuntimeToken
+
 		ctx = common.WithDryrun(ctx, input.dryrun)
 		if watch, err := cmd.Flags().GetBool("watch"); err != nil {
 			return err

pkg/artifacts/server.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"net"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -275,12 +276,12 @@ func downloads(router *httprouter.Router, baseDir string, fsys fs.FS) {
 	})
 }
 
-func Serve(ctx context.Context, artifactPath string, addr string, port string) context.CancelFunc {
+func Serve(ctx context.Context, artifactPath string, addr string, port uint16) (context.CancelFunc, *http.Server) {
 	serverContext, cancel := context.WithCancel(ctx)
 	logger := common.Logger(serverContext)
 
 	if artifactPath == "" {
-		return cancel
+		return cancel, nil
 	}
 
 	router := httprouter.New()
@@ -290,16 +291,17 @@ func Serve(ctx context.Context, artifactPath string, addr string, port string) c
 	uploads(router, artifactPath, fsys)
 	downloads(router, artifactPath, fsys)
 
+	listener, _ := net.Listen("tcp", fmt.Sprintf("%s:%d", addr, port))
 	server := &http.Server{
-		Addr:              fmt.Sprintf("%s:%s", addr, port),
+		Addr:              listener.Addr().String(),
 		ReadHeaderTimeout: 2 * time.Second,
 		Handler:           router,
 	}
 
 	// run server
 	go func() {
-		logger.Infof("Start server on http://%s:%s", addr, port)
-		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+		logger.Debugf("Start Artifact Server on http://%s", listener.Addr())
+		if err := server.Serve(listener); err != nil && err != http.ErrServerClosed {
 			logger.Fatal(err)
 		}
 	}()
@@ -314,5 +316,5 @@ func Serve(ctx context.Context, artifactPath string, addr string, port string) c
 		}
 	}()
 
-	return cancel
+	return cancel, server
 }

pkg/artifacts/server_test.go

@@ -240,9 +240,9 @@ type TestJobFileInfo struct {
 }
 
 var (
-	artifactsPath = path.Join(os.TempDir(), "test-artifacts")
-	artifactsAddr = "127.0.0.1"
-	artifactsPort = "12345"
+	artifactsPath        = path.Join(os.TempDir(), "test-artifacts")
+	artifactsAddr        = "127.0.0.1"
+	artifactsPort uint16 = 12345
 )
 
 func TestArtifactFlow(t *testing.T) {
@@ -252,7 +252,7 @@ func TestArtifactFlow(t *testing.T) {
 
 	ctx := context.Background()
 
-	cancel := Serve(ctx, artifactsPath, artifactsAddr, artifactsPort)
+	cancel, _ := Serve(ctx, artifactsPath, artifactsAddr, artifactsPort)
 	defer cancel()
 
 	platforms := map[string]string{

pkg/runner/run_context.go

@@ -936,10 +936,6 @@ func (rc *RunContext) withGithubEnv(ctx context.Context, github *model.GithubCon
 	env["GITHUB_API_URL"] = github.APIURL
 	env["GITHUB_GRAPHQL_URL"] = github.GraphQLURL
 
-	if rc.Config.ArtifactServerPath != "" {
-		setActionRuntimeVars(rc, env)
-	}
-
 	for _, platformName := range rc.runsOnPlatformNames(ctx) {
 		if platformName != "" {
 			if platformName == "ubuntu-latest" {
@@ -955,20 +951,6 @@ func (rc *RunContext) withGithubEnv(ctx context.Context, github *model.GithubCon
 	return env
 }
 
-func setActionRuntimeVars(rc *RunContext, env map[string]string) {
-	actionsRuntimeURL := os.Getenv("ACTIONS_RUNTIME_URL")
-	if actionsRuntimeURL == "" {
-		actionsRuntimeURL = fmt.Sprintf("http://%s:%s/", rc.Config.ArtifactServerAddr, rc.Config.ArtifactServerPort)
-	}
-	env["ACTIONS_RUNTIME_URL"] = actionsRuntimeURL
-
-	actionsRuntimeToken := os.Getenv("ACTIONS_RUNTIME_TOKEN")
-	if actionsRuntimeToken == "" {
-		actionsRuntimeToken = "token"
-	}
-	env["ACTIONS_RUNTIME_TOKEN"] = actionsRuntimeToken
-}
-
 func (rc *RunContext) handleCredentials(ctx context.Context) (string, string, error) {
 	// TODO: remove below 2 lines when we can release act with breaking changes
 	username := rc.Config.Secrets["DOCKER_USERNAME"]

pkg/runner/runner.go

@@ -53,7 +53,7 @@ type Config struct {
 	AutoRemove                         bool                         // controls if the container is automatically removed upon workflow completion
 	ArtifactServerPath                 string                       // the path where the artifact server stores uploads
 	ArtifactServerAddr                 string                       // the address the artifact server binds to
-	ArtifactServerPort                 string                       // the port the artifact server binds to
+	ArtifactServerPort                 uint16                       // the port the artifact server binds to
 	NoSkipCheckout                     bool                         // do not skip actions/checkout
 	RemoteName                         string                       // remote name in local git repo config
 	ReplaceGheActionWithGithubCom      []string                     // Use actions from GitHub Enterprise instance to GitHub