Use promhttp and setup logger
This commit is contained in:
Johannes 'fish' Ziemke
parent
3e266e28b9
commit
3983cd58ff
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@ -25,6 +25,7 @@ import (
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"time"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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"github.com/prometheus/common/log"
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"github.com/prometheus/common/version"
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"github.com/prometheus/node_exporter/collector"
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@ -157,12 +158,11 @@ func main() {
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log.Infof(" - %s", n)
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}
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nodeCollector := NodeCollector{collectors: collectors}
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prometheus.MustRegister(nodeCollector)
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prometheus.MustRegister(NodeCollector{collectors: collectors})
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handler := promhttp.HandlerFor(prometheus.DefaultGatherer,
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promhttp.HandlerOpts{ErrorLog: log.NewErrorLogger()})
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handler := prometheus.Handler()
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http.Handle(*metricsPath, handler)
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http.Handle(*metricsPath, prometheus.InstrumentHandler("prometheus", handler))
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http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
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w.Write([]byte(`<html>
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<head><title>Node Exporter</title></head>
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201
vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go
generated
vendored
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201
vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go
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vendored
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@ -0,0 +1,201 @@
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// Copyright 2016 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Copyright (c) 2013, The Prometheus Authors
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// All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license that can be found
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// in the LICENSE file.
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// Package promhttp contains functions to create http.Handler instances to
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// expose Prometheus metrics via HTTP. In later versions of this package, it
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// will also contain tooling to instrument instances of http.Handler and
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// http.RoundTripper.
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//
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// promhttp.Handler acts on the prometheus.DefaultGatherer. With HandlerFor,
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// you can create a handler for a custom registry or anything that implements
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// the Gatherer interface. It also allows to create handlers that act
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// differently on errors or allow to log errors.
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package promhttp
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import (
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"bytes"
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"compress/gzip"
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"fmt"
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"io"
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"net/http"
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"strings"
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"sync"
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"github.com/prometheus/common/expfmt"
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"github.com/prometheus/client_golang/prometheus"
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)
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const (
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contentTypeHeader = "Content-Type"
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contentLengthHeader = "Content-Length"
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contentEncodingHeader = "Content-Encoding"
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acceptEncodingHeader = "Accept-Encoding"
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)
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var bufPool sync.Pool
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func getBuf() *bytes.Buffer {
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buf := bufPool.Get()
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if buf == nil {
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return &bytes.Buffer{}
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}
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return buf.(*bytes.Buffer)
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}
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func giveBuf(buf *bytes.Buffer) {
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buf.Reset()
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bufPool.Put(buf)
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}
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// Handler returns an HTTP handler for the prometheus.DefaultGatherer. The
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// Handler uses the default HandlerOpts, i.e. report the first error as an HTTP
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// error, no error logging, and compression if requested by the client.
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//
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// If you want to create a Handler for the DefaultGatherer with different
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// HandlerOpts, create it with HandlerFor with prometheus.DefaultGatherer and
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// your desired HandlerOpts.
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func Handler() http.Handler {
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return HandlerFor(prometheus.DefaultGatherer, HandlerOpts{})
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}
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// HandlerFor returns an http.Handler for the provided Gatherer. The behavior
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// of the Handler is defined by the provided HandlerOpts.
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func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
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mfs, err := reg.Gather()
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if err != nil {
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if opts.ErrorLog != nil {
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opts.ErrorLog.Println("error gathering metrics:", err)
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}
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switch opts.ErrorHandling {
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case PanicOnError:
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panic(err)
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case ContinueOnError:
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if len(mfs) == 0 {
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http.Error(w, "No metrics gathered, last error:\n\n"+err.Error(), http.StatusInternalServerError)
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return
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}
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case HTTPErrorOnError:
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http.Error(w, "An error has occurred during metrics gathering:\n\n"+err.Error(), http.StatusInternalServerError)
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return
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}
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}
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contentType := expfmt.Negotiate(req.Header)
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buf := getBuf()
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defer giveBuf(buf)
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writer, encoding := decorateWriter(req, buf, opts.DisableCompression)
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enc := expfmt.NewEncoder(writer, contentType)
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var lastErr error
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for _, mf := range mfs {
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if err := enc.Encode(mf); err != nil {
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lastErr = err
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if opts.ErrorLog != nil {
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opts.ErrorLog.Println("error encoding metric family:", err)
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}
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switch opts.ErrorHandling {
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case PanicOnError:
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panic(err)
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case ContinueOnError:
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// Handled later.
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case HTTPErrorOnError:
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http.Error(w, "An error has occurred during metrics encoding:\n\n"+err.Error(), http.StatusInternalServerError)
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return
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}
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}
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}
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if closer, ok := writer.(io.Closer); ok {
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closer.Close()
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}
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if lastErr != nil && buf.Len() == 0 {
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http.Error(w, "No metrics encoded, last error:\n\n"+err.Error(), http.StatusInternalServerError)
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return
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}
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header := w.Header()
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header.Set(contentTypeHeader, string(contentType))
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header.Set(contentLengthHeader, fmt.Sprint(buf.Len()))
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if encoding != "" {
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header.Set(contentEncodingHeader, encoding)
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}
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w.Write(buf.Bytes())
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// TODO(beorn7): Consider streaming serving of metrics.
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})
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}
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// HandlerErrorHandling defines how a Handler serving metrics will handle
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// errors.
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type HandlerErrorHandling int
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// These constants cause handlers serving metrics to behave as described if
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// errors are encountered.
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const (
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// Serve an HTTP status code 500 upon the first error
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// encountered. Report the error message in the body.
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HTTPErrorOnError HandlerErrorHandling = iota
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// Ignore errors and try to serve as many metrics as possible. However,
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// if no metrics can be served, serve an HTTP status code 500 and the
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// last error message in the body. Only use this in deliberate "best
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// effort" metrics collection scenarios. It is recommended to at least
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// log errors (by providing an ErrorLog in HandlerOpts) to not mask
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// errors completely.
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ContinueOnError
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// Panic upon the first error encountered (useful for "crash only" apps).
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PanicOnError
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)
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// Logger is the minimal interface HandlerOpts needs for logging. Note that
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// log.Logger from the standard library implements this interface, and it is
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// easy to implement by custom loggers, if they don't do so already anyway.
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type Logger interface {
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Println(v ...interface{})
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}
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// HandlerOpts specifies options how to serve metrics via an http.Handler. The
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// zero value of HandlerOpts is a reasonable default.
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type HandlerOpts struct {
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// ErrorLog specifies an optional logger for errors collecting and
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// serving metrics. If nil, errors are not logged at all.
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ErrorLog Logger
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// ErrorHandling defines how errors are handled. Note that errors are
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// logged regardless of the configured ErrorHandling provided ErrorLog
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// is not nil.
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ErrorHandling HandlerErrorHandling
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// If DisableCompression is true, the handler will never compress the
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// response, even if requested by the client.
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DisableCompression bool
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}
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// decorateWriter wraps a writer to handle gzip compression if requested. It
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// returns the decorated writer and the appropriate "Content-Encoding" header
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// (which is empty if no compression is enabled).
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func decorateWriter(request *http.Request, writer io.Writer, compressionDisabled bool) (io.Writer, string) {
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if compressionDisabled {
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return writer, ""
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}
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header := request.Header.Get(acceptEncodingHeader)
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parts := strings.Split(header, ",")
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for _, part := range parts {
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part := strings.TrimSpace(part)
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if part == "gzip" || strings.HasPrefix(part, "gzip;") {
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return gzip.NewWriter(writer), "gzip"
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}
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}
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return writer, ""
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}
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@ -56,6 +56,12 @@
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"revision": "c5b7fccd204277076155f10851dad72b76a49317",
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"revisionTime": "2016-08-17T15:48:24Z"
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},
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{
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"checksumSHA1": "lG3//eDlwqA4IOuAPrNtLh9G0TA=",
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"path": "github.com/prometheus/client_golang/prometheus/promhttp",
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"revision": "575f371f7862609249a1be4c9145f429fe065e32",
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"revisionTime": "2016-11-24T15:57:32Z"
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},
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{
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"checksumSHA1": "DvwvOlPNAgRntBzt3b3OSRMS2N4=",
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"path": "github.com/prometheus/client_model/go",
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