diff options
Diffstat (limited to 'vendor/github.com/prometheus/client_golang/prometheus/promhttp')
5 files changed, 267 insertions, 15 deletions
diff --git a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator.go b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator.go index 5ee095b09..9c1c66dcc 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator.go @@ -102,10 +102,10 @@ func init() { return d } pickDelegator[closeNotifier] = func(d *responseWriterDelegator) delegator { // 1 - return closeNotifierDelegator{d} + return &closeNotifierDelegator{d} } pickDelegator[flusher] = func(d *responseWriterDelegator) delegator { // 2 - return flusherDelegator{d} + return &flusherDelegator{d} } pickDelegator[flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 3 return struct { @@ -115,7 +115,7 @@ func init() { }{d, &flusherDelegator{d}, &closeNotifierDelegator{d}} } pickDelegator[hijacker] = func(d *responseWriterDelegator) delegator { // 4 - return hijackerDelegator{d} + return &hijackerDelegator{d} } pickDelegator[hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 5 return struct { diff --git a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator_1_8.go b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator_1_8.go index f4d386f7a..75a905e2f 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator_1_8.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator_1_8.go @@ -28,7 +28,7 @@ func (d *pusherDelegator) Push(target string, opts *http.PushOptions) error { func init() { pickDelegator[pusher] = func(d *responseWriterDelegator) delegator { // 16 - return pusherDelegator{d} + return &pusherDelegator{d} } pickDelegator[pusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 17 return struct { diff --git a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go index 2d67f2496..8dc260355 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go @@ -39,6 +39,7 @@ import ( "net/http" "strings" "sync" + "time" "github.com/prometheus/common/expfmt" @@ -67,21 +68,51 @@ func giveBuf(buf *bytes.Buffer) { bufPool.Put(buf) } -// Handler returns an HTTP handler for the prometheus.DefaultGatherer. The -// Handler uses the default HandlerOpts, i.e. report the first error as an HTTP -// error, no error logging, and compression if requested by the client. +// Handler returns an http.Handler for the prometheus.DefaultGatherer, using +// default HandlerOpts, i.e. it reports the first error as an HTTP error, it has +// no error logging, and it applies compression if requested by the client. // -// If you want to create a Handler for the DefaultGatherer with different -// HandlerOpts, create it with HandlerFor with prometheus.DefaultGatherer and -// your desired HandlerOpts. +// The returned http.Handler is already instrumented using the +// InstrumentMetricHandler function and the prometheus.DefaultRegisterer. If you +// create multiple http.Handlers by separate calls of the Handler function, the +// metrics used for instrumentation will be shared between them, providing +// global scrape counts. +// +// This function is meant to cover the bulk of basic use cases. If you are doing +// anything that requires more customization (including using a non-default +// Gatherer, different instrumentation, and non-default HandlerOpts), use the +// HandlerFor function. See there for details. func Handler() http.Handler { - return HandlerFor(prometheus.DefaultGatherer, HandlerOpts{}) + return InstrumentMetricHandler( + prometheus.DefaultRegisterer, HandlerFor(prometheus.DefaultGatherer, HandlerOpts{}), + ) } -// HandlerFor returns an http.Handler for the provided Gatherer. The behavior -// of the Handler is defined by the provided HandlerOpts. +// HandlerFor returns an uninstrumented http.Handler for the provided +// Gatherer. The behavior of the Handler is defined by the provided +// HandlerOpts. Thus, HandlerFor is useful to create http.Handlers for custom +// Gatherers, with non-default HandlerOpts, and/or with custom (or no) +// instrumentation. Use the InstrumentMetricHandler function to apply the same +// kind of instrumentation as it is used by the Handler function. func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler { - return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) { + var inFlightSem chan struct{} + if opts.MaxRequestsInFlight > 0 { + inFlightSem = make(chan struct{}, opts.MaxRequestsInFlight) + } + + h := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) { + if inFlightSem != nil { + select { + case inFlightSem <- struct{}{}: // All good, carry on. + defer func() { <-inFlightSem }() + default: + http.Error(w, fmt.Sprintf( + "Limit of concurrent requests reached (%d), try again later.", opts.MaxRequestsInFlight, + ), http.StatusServiceUnavailable) + return + } + } + mfs, err := reg.Gather() if err != nil { if opts.ErrorLog != nil { @@ -137,9 +168,70 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler { if encoding != "" { header.Set(contentEncodingHeader, encoding) } - w.Write(buf.Bytes()) + if _, err := w.Write(buf.Bytes()); err != nil && opts.ErrorLog != nil { + opts.ErrorLog.Println("error while sending encoded metrics:", err) + } // TODO(beorn7): Consider streaming serving of metrics. }) + + if opts.Timeout <= 0 { + return h + } + return http.TimeoutHandler(h, opts.Timeout, fmt.Sprintf( + "Exceeded configured timeout of %v.\n", + opts.Timeout, + )) +} + +// InstrumentMetricHandler is usually used with an http.Handler returned by the +// HandlerFor function. It instruments the provided http.Handler with two +// metrics: A counter vector "promhttp_metric_handler_requests_total" to count +// scrapes partitioned by HTTP status code, and a gauge +// "promhttp_metric_handler_requests_in_flight" to track the number of +// simultaneous scrapes. This function idempotently registers collectors for +// both metrics with the provided Registerer. It panics if the registration +// fails. The provided metrics are useful to see how many scrapes hit the +// monitored target (which could be from different Prometheus servers or other +// scrapers), and how often they overlap (which would result in more than one +// scrape in flight at the same time). Note that the scrapes-in-flight gauge +// will contain the scrape by which it is exposed, while the scrape counter will +// only get incremented after the scrape is complete (as only then the status +// code is known). For tracking scrape durations, use the +// "scrape_duration_seconds" gauge created by the Prometheus server upon each +// scrape. +func InstrumentMetricHandler(reg prometheus.Registerer, handler http.Handler) http.Handler { + cnt := prometheus.NewCounterVec( + prometheus.CounterOpts{ + Name: "promhttp_metric_handler_requests_total", + Help: "Total number of scrapes by HTTP status code.", + }, + []string{"code"}, + ) + // Initialize the most likely HTTP status codes. + cnt.WithLabelValues("200") + cnt.WithLabelValues("500") + cnt.WithLabelValues("503") + if err := reg.Register(cnt); err != nil { + if are, ok := err.(prometheus.AlreadyRegisteredError); ok { + cnt = are.ExistingCollector.(*prometheus.CounterVec) + } else { + panic(err) + } + } + + gge := prometheus.NewGauge(prometheus.GaugeOpts{ + Name: "promhttp_metric_handler_requests_in_flight", + Help: "Current number of scrapes being served.", + }) + if err := reg.Register(gge); err != nil { + if are, ok := err.(prometheus.AlreadyRegisteredError); ok { + gge = are.ExistingCollector.(prometheus.Gauge) + } else { + panic(err) + } + } + + return InstrumentHandlerCounter(cnt, InstrumentHandlerInFlight(gge, handler)) } // HandlerErrorHandling defines how a Handler serving metrics will handle @@ -183,6 +275,21 @@ type HandlerOpts struct { // If DisableCompression is true, the handler will never compress the // response, even if requested by the client. DisableCompression bool + // The number of concurrent HTTP requests is limited to + // MaxRequestsInFlight. Additional requests are responded to with 503 + // Service Unavailable and a suitable message in the body. If + // MaxRequestsInFlight is 0 or negative, no limit is applied. + MaxRequestsInFlight int + // If handling a request takes longer than Timeout, it is responded to + // with 503 ServiceUnavailable and a suitable Message. No timeout is + // applied if Timeout is 0 or negative. Note that with the current + // implementation, reaching the timeout simply ends the HTTP requests as + // described above (and even that only if sending of the body hasn't + // started yet), while the bulk work of gathering all the metrics keeps + // running in the background (with the eventual result to be thrown + // away). Until the implementation is improved, it is recommended to + // implement a separate timeout in potentially slow Collectors. + Timeout time.Duration } // decorateWriter wraps a writer to handle gzip compression if requested. It diff --git a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http_test.go b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http_test.go index 413ff7baa..aeaa0b4d7 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http_test.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http_test.go @@ -19,7 +19,9 @@ import ( "log" "net/http" "net/http/httptest" + "strings" "testing" + "time" "github.com/prometheus/client_golang/prometheus" ) @@ -37,6 +39,23 @@ func (e errorCollector) Collect(ch chan<- prometheus.Metric) { ) } +type blockingCollector struct { + CollectStarted, Block chan struct{} +} + +func (b blockingCollector) Describe(ch chan<- *prometheus.Desc) { + ch <- prometheus.NewDesc("dummy_desc", "not helpful", nil, nil) +} + +func (b blockingCollector) Collect(ch chan<- prometheus.Metric) { + select { + case b.CollectStarted <- struct{}{}: + default: + } + // Collects nothing, just waits for a channel receive. + <-b.Block +} + func TestHandlerErrorHandling(t *testing.T) { // Create a registry that collects a MetricFamily with two elements, @@ -129,3 +148,103 @@ the_count 0 }() panicHandler.ServeHTTP(writer, request) } + +func TestInstrumentMetricHandler(t *testing.T) { + reg := prometheus.NewRegistry() + handler := InstrumentMetricHandler(reg, HandlerFor(reg, HandlerOpts{})) + // Do it again to test idempotency. + InstrumentMetricHandler(reg, HandlerFor(reg, HandlerOpts{})) + writer := httptest.NewRecorder() + request, _ := http.NewRequest("GET", "/", nil) + request.Header.Add("Accept", "test/plain") + + handler.ServeHTTP(writer, request) + if got, want := writer.Code, http.StatusOK; got != want { + t.Errorf("got HTTP status code %d, want %d", got, want) + } + + want := "promhttp_metric_handler_requests_in_flight 1\n" + if got := writer.Body.String(); !strings.Contains(got, want) { + t.Errorf("got body %q, does not contain %q", got, want) + } + want = "promhttp_metric_handler_requests_total{code=\"200\"} 0\n" + if got := writer.Body.String(); !strings.Contains(got, want) { + t.Errorf("got body %q, does not contain %q", got, want) + } + + writer.Body.Reset() + handler.ServeHTTP(writer, request) + if got, want := writer.Code, http.StatusOK; got != want { + t.Errorf("got HTTP status code %d, want %d", got, want) + } + + want = "promhttp_metric_handler_requests_in_flight 1\n" + if got := writer.Body.String(); !strings.Contains(got, want) { + t.Errorf("got body %q, does not contain %q", got, want) + } + want = "promhttp_metric_handler_requests_total{code=\"200\"} 1\n" + if got := writer.Body.String(); !strings.Contains(got, want) { + t.Errorf("got body %q, does not contain %q", got, want) + } +} + +func TestHandlerMaxRequestsInFlight(t *testing.T) { + reg := prometheus.NewRegistry() + handler := HandlerFor(reg, HandlerOpts{MaxRequestsInFlight: 1}) + w1 := httptest.NewRecorder() + w2 := httptest.NewRecorder() + w3 := httptest.NewRecorder() + request, _ := http.NewRequest("GET", "/", nil) + request.Header.Add("Accept", "test/plain") + + c := blockingCollector{Block: make(chan struct{}), CollectStarted: make(chan struct{}, 1)} + reg.MustRegister(c) + + rq1Done := make(chan struct{}) + go func() { + handler.ServeHTTP(w1, request) + close(rq1Done) + }() + <-c.CollectStarted + + handler.ServeHTTP(w2, request) + + if got, want := w2.Code, http.StatusServiceUnavailable; got != want { + t.Errorf("got HTTP status code %d, want %d", got, want) + } + if got, want := w2.Body.String(), "Limit of concurrent requests reached (1), try again later.\n"; got != want { + t.Errorf("got body %q, want %q", got, want) + } + + close(c.Block) + <-rq1Done + + handler.ServeHTTP(w3, request) + + if got, want := w3.Code, http.StatusOK; got != want { + t.Errorf("got HTTP status code %d, want %d", got, want) + } +} + +func TestHandlerTimeout(t *testing.T) { + reg := prometheus.NewRegistry() + handler := HandlerFor(reg, HandlerOpts{Timeout: time.Millisecond}) + w := httptest.NewRecorder() + + request, _ := http.NewRequest("GET", "/", nil) + request.Header.Add("Accept", "test/plain") + + c := blockingCollector{Block: make(chan struct{}), CollectStarted: make(chan struct{}, 1)} + reg.MustRegister(c) + + handler.ServeHTTP(w, request) + + if got, want := w.Code, http.StatusServiceUnavailable; got != want { + t.Errorf("got HTTP status code %d, want %d", got, want) + } + if got, want := w.Body.String(), "Exceeded configured timeout of 1ms.\n"; got != want { + t.Errorf("got body %q, want %q", got, want) + } + + close(c.Block) // To not leak a goroutine. +} diff --git a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server_test.go b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server_test.go index e9af63e04..716c6f45e 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server_test.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server_test.go @@ -281,6 +281,16 @@ func (t *testResponseWriter) ReadFrom(io.Reader) (int64, error) { return 0, nil } +// testFlusher is an http.ResponseWriter that also implements http.Flusher. +type testFlusher struct { + flushCalled bool +} + +func (t *testFlusher) Header() http.Header { return nil } +func (t *testFlusher) Write([]byte) (int, error) { return 0, nil } +func (t *testFlusher) WriteHeader(int) {} +func (t *testFlusher) Flush() { t.flushCalled = true } + func TestInterfaceUpgrade(t *testing.T) { w := &testResponseWriter{} d := newDelegator(w, nil) @@ -299,6 +309,22 @@ func TestInterfaceUpgrade(t *testing.T) { if _, ok := d.(http.Hijacker); ok { t.Error("delegator unexpectedly implements http.Hijacker") } + + f := &testFlusher{} + d = newDelegator(f, nil) + if _, ok := d.(http.CloseNotifier); ok { + t.Error("delegator unexpectedly implements http.CloseNotifier") + } + d.(http.Flusher).Flush() + if !w.flushCalled { + t.Error("Flush not called") + } + if _, ok := d.(io.ReaderFrom); ok { + t.Error("delegator unexpectedly implements io.ReaderFrom") + } + if _, ok := d.(http.Hijacker); ok { + t.Error("delegator unexpectedly implements http.Hijacker") + } } func ExampleInstrumentHandlerDuration() { |