cmd/opm: serve pprof endpoints by default

There is no substantial runtime cost to serving pprof endpoints, and
when things hit the fan and we need to investigate performance in situ,
there is no time to restart pods and change flags. Capturing profiles
remains opt-in, since those are costly.

Signed-off-by: Steve Kuznetsov <skuznets@redhat.com>

cmd/opm/serve/serve.go

@@ -36,8 +36,9 @@ type serve struct {
 	port           string
 	terminationLog string
 
-	debug     bool
-	pprofAddr string
+	debug           bool
+	pprofAddr       string
+	captureProfiles bool
 
 	logger *logrus.Entry
 }
@@ -80,7 +81,8 @@ will not be reflected in the served content.
 	cmd.Flags().BoolVar(&s.debug, "debug", false, "enable debug logging")
 	cmd.Flags().StringVarP(&s.terminationLog, "termination-log", "t", "/dev/termination-log", "path to a container termination log file")
 	cmd.Flags().StringVarP(&s.port, "port", "p", "50051", "port number to serve on")
-	cmd.Flags().StringVar(&s.pprofAddr, "pprof-addr", "", "address of startup profiling endpoint (addr:port format)")
+	cmd.Flags().StringVar(&s.pprofAddr, "pprof-addr", "localhost:6060", "address of startup profiling endpoint (addr:port format)")
+	cmd.Flags().BoolVar(&s.captureProfiles, "pprof-capture-profiles", false, "capture pprof CPU profiles")
 	cmd.Flags().StringVar(&s.cacheDir, "cache-dir", "", "if set, sync and persist server cache directory")
 	cmd.Flags().BoolVar(&s.cacheOnly, "cache-only", false, "sync the serve cache and exit without serving")
 	cmd.Flags().BoolVar(&s.cacheEnforceIntegrity, "cache-enforce-integrity", false, "exit with error if cache is not present or has been invalidated. (default: true when --cache-dir is set and --cache-only is false, false otherwise), ")
@@ -92,8 +94,10 @@ func (s *serve) run(ctx context.Context) error {
 	if err := p.startEndpoint(); err != nil {
 		return fmt.Errorf("could not start pprof endpoint: %v", err)
 	}
-	if err := p.startCpuProfileCache(); err != nil {
-		return fmt.Errorf("could not start CPU profile: %v", err)
+	if s.captureProfiles {
+		if err := p.startCpuProfileCache(); err != nil {
+			return fmt.Errorf("could not start CPU profile: %v", err)
+		}
 	}
 
 	// Immediately set up termination log

pkg/cache/tar_test.go

@@ -51,7 +51,7 @@ func Test_fsToTar(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			w := bytes.Buffer{}
-			err := fsToTar(&w, tc.fsys())
+			err := fsToTar(&w, tc.fsys(), nil)
 			tc.expect(t, w.Bytes(), err)
 		})
 	}