// 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)
}
// startProxy launches an HTTP proxy for client communication which proxies to other etcd nodes.
func startProxy(cfg *config) error {
urlsmap, _, err := getPeerURLsMapAndToken(cfg, "proxy")
if err != nil {
return fmt.Errorf("error setting up initial cluster: %v", err)
}
pt, err := transport.NewTimeoutTransport(cfg.peerTLSInfo, time.Duration(cfg.proxyDialTimeoutMs)*time.Millisecond, time.Duration(cfg.proxyReadTimeoutMs)*time.Millisecond, time.Duration(cfg.proxyWriteTimeoutMs)*time.Millisecond)
if err != nil {
return err
}
pt.MaxIdleConnsPerHost = proxy.DefaultMaxIdleConnsPerHost
tr, err := transport.NewTimeoutTransport(cfg.peerTLSInfo, time.Duration(cfg.proxyDialTimeoutMs)*time.Millisecond, time.Duration(cfg.proxyReadTimeoutMs)*time.Millisecond, time.Duration(cfg.proxyWriteTimeoutMs)*time.Millisecond)
if err != nil {
return err
}
cfg.dir = path.Join(cfg.dir, "proxy")
err = os.MkdirAll(cfg.dir, 0700)
if err != nil {
return err
}
var peerURLs []string
clusterfile := path.Join(cfg.dir, "cluster")
b, err := ioutil.ReadFile(clusterfile)
switch {
case err == nil:
if cfg.durl != "" {
plog.Warningf("discovery token ignored since the proxy has already been initialized. Valid cluster file found at %q", clusterfile)
}
urls := struct{ PeerURLs []string }{}
err := json.Unmarshal(b, &urls)
if err != nil {
return err
}
peerURLs = urls.PeerURLs
plog.Infof("proxy: using peer urls %v from cluster file %q", peerURLs, clusterfile)
case os.IsNotExist(err):
if cfg.durl != "" {
s, err := discovery.GetCluster(cfg.durl, cfg.dproxy)
if err != nil {
return err
}
if urlsmap, err = types.NewURLsMap(s); err != nil {
return err
}
}
peerURLs = urlsmap.URLs()
plog.Infof("proxy: using peer urls %v ", peerURLs)
default:
return err
}
clientURLs := []string{}
uf := func() []string {
gcls, err := etcdserver.GetClusterFromRemotePeers(peerURLs, tr)
// TODO: remove the 2nd check when we fix GetClusterFromPeers
// GetClusterFromPeers should not return nil error with an invalid empty cluster
if err != nil {
plog.Warningf("proxy: %v", err)
return []string{}
}
if len(gcls.Members()) == 0 {
return clientURLs
}
clientURLs = gcls.ClientURLs()
urls := struct{ PeerURLs []string }{gcls.PeerURLs()}
b, err := json.Marshal(urls)
if err != nil {
plog.Warningf("proxy: error on marshal peer urls %s", err)
return clientURLs
}
err = ioutil.WriteFile(clusterfile+".bak", b, 0600)
if err != nil {
plog.Warningf("proxy: error on writing urls %s", err)
return clientURLs
}
err = os.Rename(clusterfile+".bak", clusterfile)
if err != nil {
plog.Warningf("proxy: error on updating clusterfile %s", err)
return clientURLs
}
if !reflect.DeepEqual(gcls.PeerURLs(), peerURLs) {
plog.Noticef("proxy: updated peer urls in cluster file from %v to %v", peerURLs, gcls.PeerURLs())
}
peerURLs = gcls.PeerURLs()
return clientURLs
}
ph := proxy.NewHandler(pt, uf, time.Duration(cfg.proxyFailureWaitMs)*time.Millisecond, time.Duration(cfg.proxyRefreshIntervalMs)*time.Millisecond)
ph = &cors.CORSHandler{
Handler: ph,
Info: cfg.corsInfo,
}
if cfg.isReadonlyProxy() {
ph = proxy.NewReadonlyHandler(ph)
}
// Start a proxy server goroutine for each listen address
for _, u := range cfg.lcurls {
l, err := transport.NewListener(u.Host, u.Scheme, cfg.clientTLSInfo)
if err != nil {
return err
}
host := u.String()
go func() {
plog.Info("proxy: listening for client requests on ", host)
mux := http.NewServeMux()
mux.Handle("/metrics", prometheus.Handler())
mux.Handle("/", ph)
plog.Fatal(http.Serve(l, mux))
}()
}
return nil
}
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.
}