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 | 311 |
1 files changed, 0 insertions, 311 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 deleted file mode 100644 index 0135737..0000000 --- a/vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go +++ /dev/null @@ -1,311 +0,0 @@ -// Copyright 2016 The Prometheus Authors -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// Package promhttp provides tooling around HTTP servers and clients. -// -// 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. -// -// 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. -package promhttp - -import ( - "bytes" - "compress/gzip" - "fmt" - "io" - "net/http" - "strings" - "sync" - "time" - - "github.com/prometheus/common/expfmt" - - "github.com/prometheus/client_golang/prometheus" -) - -const ( - contentTypeHeader = "Content-Type" - contentLengthHeader = "Content-Length" - contentEncodingHeader = "Content-Encoding" - acceptEncodingHeader = "Accept-Encoding" -) - -var bufPool sync.Pool - -func getBuf() *bytes.Buffer { - buf := bufPool.Get() - if buf == nil { - return &bytes.Buffer{} - } - return buf.(*bytes.Buffer) -} - -func giveBuf(buf *bytes.Buffer) { - buf.Reset() - 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. -// -// 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 InstrumentMetricHandler( - prometheus.DefaultRegisterer, 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. -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 - } - } - - mfs, err := reg.Gather() - if err != nil { - if opts.ErrorLog != nil { - opts.ErrorLog.Println("error gathering metrics:", err) - } - switch opts.ErrorHandling { - case PanicOnError: - panic(err) - case ContinueOnError: - if len(mfs) == 0 { - http.Error(w, "No metrics gathered, last error:\n\n"+err.Error(), http.StatusInternalServerError) - return - } - case HTTPErrorOnError: - http.Error(w, "An error has occurred during metrics gathering:\n\n"+err.Error(), http.StatusInternalServerError) - return - } - } - - contentType := expfmt.Negotiate(req.Header) - buf := getBuf() - defer giveBuf(buf) - writer, encoding := decorateWriter(req, buf, opts.DisableCompression) - enc := expfmt.NewEncoder(writer, contentType) - var lastErr error - for _, mf := range mfs { - if err := enc.Encode(mf); err != nil { - lastErr = err - if opts.ErrorLog != nil { - opts.ErrorLog.Println("error encoding metric family:", err) - } - switch opts.ErrorHandling { - case PanicOnError: - panic(err) - case ContinueOnError: - // Handled later. - case HTTPErrorOnError: - http.Error(w, "An error has occurred during metrics encoding:\n\n"+err.Error(), http.StatusInternalServerError) - return - } - } - } - if closer, ok := writer.(io.Closer); ok { - closer.Close() - } - if lastErr != nil && buf.Len() == 0 { - http.Error(w, "No metrics encoded, last error:\n\n"+lastErr.Error(), http.StatusInternalServerError) - return - } - header := w.Header() - header.Set(contentTypeHeader, string(contentType)) - header.Set(contentLengthHeader, fmt.Sprint(buf.Len())) - 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) - } - // 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 -// errors. -type HandlerErrorHandling int - -// These constants cause handlers serving metrics to behave as described if -// errors are encountered. -const ( - // Serve an HTTP status code 500 upon the first error - // encountered. Report the error message in the body. - HTTPErrorOnError HandlerErrorHandling = iota - // Ignore errors and try to serve as many metrics as possible. However, - // if no metrics can be served, serve an HTTP status code 500 and the - // last error message in the body. Only use this in deliberate "best - // effort" metrics collection scenarios. It is recommended to at least - // log errors (by providing an ErrorLog in HandlerOpts) to not mask - // errors completely. - ContinueOnError - // Panic upon the first error encountered (useful for "crash only" apps). - PanicOnError -) - -// Logger is the minimal interface HandlerOpts needs for logging. Note that -// log.Logger from the standard library implements this interface, and it is -// easy to implement by custom loggers, if they don't do so already anyway. -type Logger interface { - Println(v ...interface{}) -} - -// HandlerOpts specifies options how to serve metrics via an http.Handler. The -// zero value of HandlerOpts is a reasonable default. -type HandlerOpts struct { - // ErrorLog specifies an optional logger for errors collecting and - // serving metrics. If nil, errors are not logged at all. - ErrorLog Logger - // ErrorHandling defines how errors are handled. Note that errors are - // logged regardless of the configured ErrorHandling provided ErrorLog - // is not nil. - ErrorHandling HandlerErrorHandling - // 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 -// returns the decorated writer and the appropriate "Content-Encoding" header -// (which is empty if no compression is enabled). -func decorateWriter(request *http.Request, writer io.Writer, compressionDisabled bool) (io.Writer, string) { - if compressionDisabled { - return writer, "" - } - header := request.Header.Get(acceptEncodingHeader) - parts := strings.Split(header, ",") - for _, part := range parts { - part = strings.TrimSpace(part) - if part == "gzip" || strings.HasPrefix(part, "gzip;") { - return gzip.NewWriter(writer), "gzip" - } - } - return writer, "" -} |