Example #1
0
// NewClientHandler generates a muxed http.Handler with the given parameters to serve etcd client requests.
func NewClientHandler(server *etcdserver.EtcdServer, timeout time.Duration) http.Handler {
	go capabilityLoop(server)

	sec := auth.NewStore(server, timeout)

	kh := &keysHandler{
		sec:     sec,
		server:  server,
		cluster: server.Cluster(),
		timer:   server,
		timeout: timeout,
	}

	sh := &statsHandler{
		stats: server,
	}

	mh := &membersHandler{
		sec:     sec,
		server:  server,
		cluster: server.Cluster(),
		timeout: timeout,
		clock:   clockwork.NewRealClock(),
	}

	dmh := &deprecatedMachinesHandler{
		cluster: server.Cluster(),
	}

	sech := &authHandler{
		sec:     sec,
		cluster: server.Cluster(),
	}

	mux := http.NewServeMux()
	mux.HandleFunc("/", http.NotFound)
	mux.Handle(healthPath, healthHandler(server))
	mux.HandleFunc(versionPath, versionHandler(server.Cluster(), serveVersion))
	mux.Handle(keysPrefix, kh)
	mux.Handle(keysPrefix+"/", kh)
	mux.HandleFunc(statsPrefix+"/store", sh.serveStore)
	mux.HandleFunc(statsPrefix+"/self", sh.serveSelf)
	mux.HandleFunc(statsPrefix+"/leader", sh.serveLeader)
	mux.HandleFunc(varsPath, serveVars)
	mux.HandleFunc(configPath+"/local/log", logHandleFunc)
	mux.Handle(metricsPath, prometheus.Handler())
	mux.Handle(membersPrefix, mh)
	mux.Handle(membersPrefix+"/", mh)
	mux.Handle(deprecatedMachinesPrefix, dmh)
	handleAuth(mux, sech)

	return requestLogger(mux)
}
Example #2
0
func ExampleRegister() {
	// Imagine you have a worker pool and want to count the tasks completed.
	taskCounter := prometheus.NewCounter(prometheus.CounterOpts{
		Subsystem: "worker_pool",
		Name:      "completed_tasks_total",
		Help:      "Total number of tasks completed.",
	})
	// This will register fine.
	if err := prometheus.Register(taskCounter); err != nil {
		fmt.Println(err)
	} else {
		fmt.Println("taskCounter registered.")
	}
	// Don't forget to tell the HTTP server about the Prometheus handler.
	// (In a real program, you still need to start the HTTP server...)
	http.Handle("/metrics", prometheus.Handler())

	// Now you can start workers and give every one of them a pointer to
	// taskCounter and let it increment it whenever it completes a task.
	taskCounter.Inc() // This has to happen somewhere in the worker code.

	// But wait, you want to see how individual workers perform. So you need
	// a vector of counters, with one element for each worker.
	taskCounterVec := prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Subsystem: "worker_pool",
			Name:      "completed_tasks_total",
			Help:      "Total number of tasks completed.",
		},
		[]string{"worker_id"},
	)

	// Registering will fail because we already have a metric of that name.
	if err := prometheus.Register(taskCounterVec); err != nil {
		fmt.Println("taskCounterVec not registered:", err)
	} else {
		fmt.Println("taskCounterVec registered.")
	}

	// To fix, first unregister the old taskCounter.
	if prometheus.Unregister(taskCounter) {
		fmt.Println("taskCounter unregistered.")
	}

	// Try registering taskCounterVec again.
	if err := prometheus.Register(taskCounterVec); err != nil {
		fmt.Println("taskCounterVec not registered:", err)
	} else {
		fmt.Println("taskCounterVec registered.")
	}
	// Bummer! Still doesn't work.

	// Prometheus will not allow you to ever export metrics with
	// inconsistent help strings or label names. After unregistering, the
	// unregistered metrics will cease to show up in the /metrics HTTP
	// response, but the registry still remembers that those metrics had
	// been exported before. For this example, we will now choose a
	// different name. (In a real program, you would obviously not export
	// the obsolete metric in the first place.)
	taskCounterVec = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Subsystem: "worker_pool",
			Name:      "completed_tasks_by_id",
			Help:      "Total number of tasks completed.",
		},
		[]string{"worker_id"},
	)
	if err := prometheus.Register(taskCounterVec); err != nil {
		fmt.Println("taskCounterVec not registered:", err)
	} else {
		fmt.Println("taskCounterVec registered.")
	}
	// Finally it worked!

	// The workers have to tell taskCounterVec their id to increment the
	// right element in the metric vector.
	taskCounterVec.WithLabelValues("42").Inc() // Code from worker 42.

	// Each worker could also keep a reference to their own counter element
	// around. Pick the counter at initialization time of the worker.
	myCounter := taskCounterVec.WithLabelValues("42") // From worker 42 initialization code.
	myCounter.Inc()                                   // Somewhere in the code of that worker.

	// Note that something like WithLabelValues("42", "spurious arg") would
	// panic (because you have provided too many label values). If you want
	// to get an error instead, use GetMetricWithLabelValues(...) instead.
	notMyCounter, err := taskCounterVec.GetMetricWithLabelValues("42", "spurious arg")
	if err != nil {
		fmt.Println("Worker initialization failed:", err)
	}
	if notMyCounter == nil {
		fmt.Println("notMyCounter is nil.")
	}

	// A different (and somewhat tricky) approach is to use
	// ConstLabels. ConstLabels are pairs of label names and label values
	// that never change. You might ask what those labels are good for (and
	// rightfully so - if they never change, they could as well be part of
	// the metric name). There are essentially two use-cases: The first is
	// if labels are constant throughout the lifetime of a binary execution,
	// but they vary over time or between different instances of a running
	// binary. The second is what we have here: Each worker creates and
	// registers an own Counter instance where the only difference is in the
	// value of the ConstLabels. Those Counters can all be registered
	// because the different ConstLabel values guarantee that each worker
	// will increment a different Counter metric.
	counterOpts := prometheus.CounterOpts{
		Subsystem:   "worker_pool",
		Name:        "completed_tasks",
		Help:        "Total number of tasks completed.",
		ConstLabels: prometheus.Labels{"worker_id": "42"},
	}
	taskCounterForWorker42 := prometheus.NewCounter(counterOpts)
	if err := prometheus.Register(taskCounterForWorker42); err != nil {
		fmt.Println("taskCounterVForWorker42 not registered:", err)
	} else {
		fmt.Println("taskCounterForWorker42 registered.")
	}
	// Obviously, in real code, taskCounterForWorker42 would be a member
	// variable of a worker struct, and the "42" would be retrieved with a
	// GetId() method or something. The Counter would be created and
	// registered in the initialization code of the worker.

	// For the creation of the next Counter, we can recycle
	// counterOpts. Just change the ConstLabels.
	counterOpts.ConstLabels = prometheus.Labels{"worker_id": "2001"}
	taskCounterForWorker2001 := prometheus.NewCounter(counterOpts)
	if err := prometheus.Register(taskCounterForWorker2001); err != nil {
		fmt.Println("taskCounterVForWorker2001 not registered:", err)
	} else {
		fmt.Println("taskCounterForWorker2001 registered.")
	}

	taskCounterForWorker2001.Inc()
	taskCounterForWorker42.Inc()
	taskCounterForWorker2001.Inc()

	// Yet another approach would be to turn the workers themselves into
	// Collectors and register them. See the Collector example for details.

	// Output:
	// taskCounter registered.
	// taskCounterVec not registered: a previously registered descriptor with the same fully-qualified name as Desc{fqName: "worker_pool_completed_tasks_total", help: "Total number of tasks completed.", constLabels: {}, variableLabels: [worker_id]} has different label names or a different help string
	// taskCounter unregistered.
	// taskCounterVec not registered: a previously registered descriptor with the same fully-qualified name as Desc{fqName: "worker_pool_completed_tasks_total", help: "Total number of tasks completed.", constLabels: {}, variableLabels: [worker_id]} has different label names or a different help string
	// taskCounterVec registered.
	// Worker initialization failed: inconsistent label cardinality
	// notMyCounter is nil.
	// taskCounterForWorker42 registered.
	// taskCounterForWorker2001 registered.
}