diff options
Diffstat (limited to 'vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go')
| -rw-r--r-- | vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go | 160 |
1 files changed, 25 insertions, 135 deletions
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 8dc260355..b6dd5a266 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go @@ -11,24 +11,21 @@ // See the License for the specific language governing permissions and // limitations under the License. -// Package promhttp provides tooling around HTTP servers and clients. +// Copyright (c) 2013, The Prometheus Authors +// All rights reserved. // -// First, the package allows the creation of http.Handler instances to expose -// Prometheus metrics via HTTP. promhttp.Handler acts on the -// prometheus.DefaultGatherer. With HandlerFor, you can create a handler for a -// custom registry or anything that implements the Gatherer interface. It also -// allows the creation of handlers that act differently on errors or allow to -// log errors. -// -// Second, the package provides tooling to instrument instances of http.Handler -// via middleware. Middleware wrappers follow the naming scheme -// InstrumentHandlerX, where X describes the intended use of the middleware. -// See each function's doc comment for specific details. +// Use of this source code is governed by a BSD-style license that can be found +// in the LICENSE file. + +// Package promhttp contains functions to create http.Handler instances to +// expose Prometheus metrics via HTTP. In later versions of this package, it +// will also contain tooling to instrument instances of http.Handler and +// http.RoundTripper. // -// Finally, the package allows for an http.RoundTripper to be instrumented via -// middleware. Middleware wrappers follow the naming scheme -// InstrumentRoundTripperX, where X describes the intended use of the -// middleware. See each function's doc comment for specific details. +// promhttp.Handler acts on the prometheus.DefaultGatherer. With HandlerFor, +// you can create a handler for a custom registry or anything that implements +// the Gatherer interface. It also allows to create handlers that act +// differently on errors or allow to log errors. package promhttp import ( @@ -39,7 +36,6 @@ import ( "net/http" "strings" "sync" - "time" "github.com/prometheus/common/expfmt" @@ -68,51 +64,21 @@ func giveBuf(buf *bytes.Buffer) { bufPool.Put(buf) } -// 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. -// -// 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. +// 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. // -// 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. +// If you want to create a Handler for the DefaultGatherer with different +// HandlerOpts, create it with HandlerFor with prometheus.DefaultGatherer and +// your desired HandlerOpts. func Handler() http.Handler { - return InstrumentMetricHandler( - prometheus.DefaultRegisterer, HandlerFor(prometheus.DefaultGatherer, HandlerOpts{}), - ) + return HandlerFor(prometheus.DefaultGatherer, 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. +// HandlerFor returns an http.Handler for the provided Gatherer. The behavior +// of the Handler is defined by the provided HandlerOpts. func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler { - 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 - } - } - + return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) { mfs, err := reg.Gather() if err != nil { if opts.ErrorLog != nil { @@ -159,7 +125,7 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler { closer.Close() } if lastErr != nil && buf.Len() == 0 { - http.Error(w, "No metrics encoded, last error:\n\n"+lastErr.Error(), http.StatusInternalServerError) + http.Error(w, "No metrics encoded, last error:\n\n"+err.Error(), http.StatusInternalServerError) return } header := w.Header() @@ -168,70 +134,9 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler { if encoding != "" { header.Set(contentEncodingHeader, encoding) } - if _, err := w.Write(buf.Bytes()); err != nil && opts.ErrorLog != nil { - opts.ErrorLog.Println("error while sending encoded metrics:", err) - } + w.Write(buf.Bytes()) // 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 @@ -275,21 +180,6 @@ 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 |