feat: add once flag to daemon command (#19) (#598)

Once flag polls and completes one job then exits.

I use this with Windows Sandbox (and creating users with local brew install on Mac) to create a fresh environment every time.

Co-authored-by: Garet Halliday <garet@pit.dev>
Co-authored-by: Jason Song <wolfogre@noreply.gitea.com>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/598
Reviewed-by: techknowlogick <techknowlogick@noreply.gitea.com>
Reviewed-by: Jason Song <wolfogre@noreply.gitea.com>
Co-authored-by: garet90 <garet90@noreply.gitea.com>
Co-committed-by: garet90 <garet90@noreply.gitea.com>

internal/app/cmd/cmd.go

@@ -42,12 +42,14 @@ func Execute(ctx context.Context) {
 	rootCmd.AddCommand(registerCmd)
 
 	// ./act_runner daemon
+	var daemArgs daemonArgs
 	daemonCmd := &cobra.Command{
 		Use:   "daemon",
 		Short: "Run as a runner daemon",
-		Args:  cobra.MaximumNArgs(1),
-		RunE:  runDaemon(ctx, &configFile),
+		Args:  cobra.MaximumNArgs(0),
+		RunE:  runDaemon(ctx, &daemArgs, &configFile),
 	}
+	daemonCmd.Flags().BoolVar(&daemArgs.Once, "once", false, "Run one job then exit")
 	rootCmd.AddCommand(daemonCmd)
 
 	// ./act_runner exec

internal/app/cmd/daemon.go

@@ -28,7 +28,7 @@ import (
 	"gitea.com/gitea/act_runner/internal/pkg/ver"
 )
 
-func runDaemon(ctx context.Context, configFile *string) func(cmd *cobra.Command, args []string) error {
+func runDaemon(ctx context.Context, daemArgs *daemonArgs, configFile *string) func(cmd *cobra.Command, args []string) error {
 	return func(cmd *cobra.Command, args []string) error {
 		cfg, err := config.LoadDefault(*configFile)
 		if err != nil {
@@ -122,9 +122,24 @@ func runDaemon(ctx context.Context, configFile *string) func(cmd *cobra.Command,
 
 		poller := poll.New(cfg, cli, runner)
 
-		go poller.Poll()
+		if daemArgs.Once {
+			done := make(chan struct{})
+			go func() {
+				defer close(done)
+				poller.PollOnce()
+			}()
+
+			// shutdown when we complete a job or cancel is requested
+			select {
+			case <-ctx.Done():
+			case <-done:
+			}
+		} else {
+			go poller.Poll()
+
+			<-ctx.Done()
+		}
 
-		<-ctx.Done()
 		log.Infof("runner: %s shutdown initiated, waiting %s for running jobs to complete before shutting down", resp.Msg.Runner.Name, cfg.Runner.ShutdownTimeout)
 
 		ctx, cancel := context.WithTimeout(context.Background(), cfg.Runner.ShutdownTimeout)
@@ -134,10 +149,15 @@ func runDaemon(ctx context.Context, configFile *string) func(cmd *cobra.Command,
 		if err != nil {
 			log.Warnf("runner: %s cancelled in progress jobs during shutdown", resp.Msg.Runner.Name)
 		}
+
 		return nil
 	}
 }
 
+type daemonArgs struct {
+	Once bool
+}
+
 // initLogging setup the global logrus logger.
 func initLogging(cfg *config.Config) {
 	isTerm := isatty.IsTerminal(os.Stdout.Fd())

internal/app/poll/poller.go

@@ -70,6 +70,15 @@ func (p *Poller) Poll() {
 	close(p.done)
 }
 
+func (p *Poller) PollOnce() {
+	limiter := rate.NewLimiter(rate.Every(p.cfg.Runner.FetchInterval), 1)
+
+	p.pollOnce(limiter)
+
+	// signal that we're done
+	close(p.done)
+}
+
 func (p *Poller) Shutdown(ctx context.Context) error {
 	p.shutdownPolling()
 
@@ -101,6 +110,19 @@ func (p *Poller) Shutdown(ctx context.Context) error {
 
 func (p *Poller) poll(wg *sync.WaitGroup, limiter *rate.Limiter) {
 	defer wg.Done()
+	for {
+		p.pollOnce(limiter)
+
+		select {
+		case <-p.pollingCtx.Done():
+			return
+		default:
+			continue
+		}
+	}
+}
+
+func (p *Poller) pollOnce(limiter *rate.Limiter) {
 	for {
 		if err := limiter.Wait(p.pollingCtx); err != nil {
 			if p.pollingCtx.Err() != nil {
@@ -114,6 +136,7 @@ func (p *Poller) poll(wg *sync.WaitGroup, limiter *rate.Limiter) {
 		}
 
 		p.runTaskWithRecover(p.jobsCtx, task)
+		return
 	}
 }