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Reintroduce AddMetricsExtraHandler on manager
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Signed-off-by: Vince Prignano <vince@prigna.com>
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vincepri authored and k8s-infra-cherrypick-robot committed May 6, 2024
1 parent 24c2359 commit 2bf6e2a
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Showing 4 changed files with 53 additions and 0 deletions.
18 changes: 18 additions & 0 deletions pkg/manager/internal.go
Original file line number Diff line number Diff line change
Expand Up @@ -179,6 +179,24 @@ func (cm *controllerManager) add(r Runnable) error {
return cm.runnables.Add(r)
}

// AddMetricsServerExtraHandler adds extra handler served on path to the http server that serves metrics.
func (cm *controllerManager) AddMetricsServerExtraHandler(path string, handler http.Handler) error {
cm.Lock()
defer cm.Unlock()
if cm.started {
return fmt.Errorf("unable to add new metrics handler because metrics endpoint has already been created")
}
if cm.metricsServer == nil {
cm.GetLogger().Info("warn: metrics server is currently disabled, registering extra handler %q will be ignored", path)
return nil
}
if err := cm.metricsServer.AddExtraHandler(path, handler); err != nil {
return err
}
cm.logger.V(2).Info("Registering metrics http server extra handler", "path", path)
return nil
}

// AddHealthzCheck allows you to add Healthz checker.
func (cm *controllerManager) AddHealthzCheck(name string, check healthz.Checker) error {
cm.Lock()
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9 changes: 9 additions & 0 deletions pkg/manager/manager.go
Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,15 @@ type Manager interface {
// election was configured.
Elected() <-chan struct{}

// AddMetricsServerExtraHandler adds an extra handler served on path to the http server that serves metrics.
// Might be useful to register some diagnostic endpoints e.g. pprof.
//
// Note that these endpoints are meant to be sensitive and shouldn't be exposed publicly.
//
// If the simple path -> handler mapping offered here is not enough,
// a new http server/listener should be added as Runnable to the manager via Add method.
AddMetricsServerExtraHandler(path string, handler http.Handler) error

// AddHealthzCheck allows you to add Healthz checker
AddHealthzCheck(name string, check healthz.Checker) error

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6 changes: 6 additions & 0 deletions pkg/manager/manager_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -1305,6 +1305,12 @@ var _ = Describe("manger.Manager", func() {
m, err := New(cfg, opts)
Expect(err).NotTo(HaveOccurred())

// Should error when we add another extra endpoint on the already registered path.
err = m.AddMetricsServerExtraHandler("/debug", http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
_, _ = w.Write([]byte("Another debug info"))
}))
Expect(err).To(HaveOccurred())

ctx, cancel := context.WithCancel(context.Background())
defer cancel()
go func() {
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20 changes: 20 additions & 0 deletions pkg/metrics/server/server.go
Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,9 @@ var DefaultBindAddress = ":8080"

// Server is a server that serves metrics.
type Server interface {
// AddExtraHandler adds extra handler served on path to the http server that serves metrics.
AddExtraHandler(path string, handler http.Handler) error

// NeedLeaderElection implements the LeaderElectionRunnable interface, which indicates
// the metrics server doesn't need leader election.
NeedLeaderElection() bool
Expand Down Expand Up @@ -179,6 +182,23 @@ func (*defaultServer) NeedLeaderElection() bool {
return false
}

// AddExtraHandler adds extra handler served on path to the http server that serves metrics.
func (s *defaultServer) AddExtraHandler(path string, handler http.Handler) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.options.ExtraHandlers == nil {
s.options.ExtraHandlers = make(map[string]http.Handler)
}
if path == defaultMetricsEndpoint {
return fmt.Errorf("overriding builtin %s endpoint is not allowed", defaultMetricsEndpoint)
}
if _, found := s.options.ExtraHandlers[path]; found {
return fmt.Errorf("can't register extra handler by duplicate path %q on metrics http server", path)
}
s.options.ExtraHandlers[path] = handler
return nil
}

// Start runs the server.
// It will install the metrics related resources depend on the server configuration.
func (s *defaultServer) Start(ctx context.Context) error {
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