add timeout to vcsLister.List() (gomods#1986)

cmd/proxy/actions/app_proxy.go

@@ -99,7 +99,7 @@ func addProxyRoutes(
 		return err
 	}
 
-	lister := module.NewVCSLister(c.GoBinary, c.GoBinaryEnvVars, fs)
+	lister := module.NewVCSLister(c.GoBinary, c.GoBinaryEnvVars, fs, c.TimeoutDuration())
 	checker := storage.WithChecker(s)
 	withSingleFlight, err := getSingleFlight(l, c, s, checker)
 	if err != nil {

pkg/download/list.go

@@ -28,7 +28,7 @@ func ListHandler(dp Protocol, lggr log.Entry, df *mode.DownloadFile) http.Handle
 
 		versions, err := dp.List(r.Context(), mod)
 		if err != nil {
-			severityLevel := errors.Expect(err, errors.KindNotFound)
+			severityLevel := errors.Expect(err, errors.KindNotFound, errors.KindGatewayTimeout)
 			err = errors.E(op, err, severityLevel)
 			lggr.SystemErr(err)
 			w.WriteHeader(errors.Kind(err))

pkg/download/protocol_test.go

@@ -50,7 +50,7 @@ func getDP(t *testing.T) Protocol {
 	return New(&Opts{
 		Storage:     s,
 		Stasher:     st,
-		Lister:      module.NewVCSLister(goBin, conf.GoBinaryEnvVars, fs),
+		Lister:      module.NewVCSLister(goBin, conf.GoBinaryEnvVars, fs, conf.TimeoutDuration()),
 		NetworkMode: Strict,
 	})
 }

pkg/errors/errors.go

@@ -18,6 +18,7 @@ const (
 	KindRateLimit      = http.StatusTooManyRequests
 	KindNotImplemented = http.StatusNotImplemented
 	KindRedirect       = http.StatusMovedPermanently
+	KindGatewayTimeout = http.StatusGatewayTimeout
 )
 
 // Error is an Athens system error.

pkg/module/go_vcs_lister.go

@@ -28,15 +28,17 @@ type vcsLister struct {
 	env       []string
 	fs        afero.Fs
 	sfg       *singleflight.Group
+	timeout   time.Duration
 }
 
 // NewVCSLister creates an UpstreamLister which uses VCS to fetch a list of available versions.
-func NewVCSLister(goBinPath string, env []string, fs afero.Fs) UpstreamLister {
+func NewVCSLister(goBinPath string, env []string, fs afero.Fs, timeout time.Duration) UpstreamLister {
 	return &vcsLister{
 		goBinPath: goBinPath,
 		env:       env,
 		fs:        fs,
 		sfg:       &singleflight.Group{},
+		timeout:   timeout,
 	}
 }
 
@@ -56,7 +58,11 @@ func (l *vcsLister) List(ctx context.Context, module string) (*storage.RevInfo,
 		}
 		defer func() { _ = l.fs.RemoveAll(tmpDir) }()
 
-		cmd := exec.Command(
+		timeoutCtx, cancel := context.WithTimeout(ctx, l.timeout)
+		defer cancel()
+
+		cmd := exec.CommandContext(
+			timeoutCtx,
 			l.goBinPath,
 			"list", "-m", "-versions", "-json",
 			config.FmtModVer(module, "latest"),
@@ -77,6 +83,10 @@ func (l *vcsLister) List(ctx context.Context, module string) (*storage.RevInfo,
 		err = cmd.Run()
 		if err != nil {
 			err = fmt.Errorf("%w: %s", err, stderr)
+			if errors.IsErr(timeoutCtx.Err(), context.DeadlineExceeded) {
+				return nil, errors.E(op, err, errors.KindGatewayTimeout)
+			}
+
 			// as of now, we can't recognize between a true NotFound
 			// and an unexpected error, so we choose the more
 			// hopeful path of NotFound. This way the Go command