k8s.io/apiserver@v0.31.1/pkg/endpoints/filters/webhook_duration.go (about)

     1  /*
     2  Copyright 2021 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package filters
    18  
    19  import (
    20  	"context"
    21  	"net/http"
    22  	"time"
    23  
    24  	"k8s.io/apimachinery/pkg/util/sets"
    25  	"k8s.io/apiserver/pkg/endpoints/request"
    26  	"k8s.io/apiserver/pkg/endpoints/responsewriter"
    27  )
    28  
    29  var (
    30  	watchVerbs = sets.NewString("watch")
    31  )
    32  
    33  // WithLatencyTrackers adds a LatencyTrackers instance to the
    34  // context associated with a request so that we can measure latency
    35  // incurred in various components within the apiserver.
    36  func WithLatencyTrackers(handler http.Handler) http.Handler {
    37  	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
    38  		ctx := req.Context()
    39  		requestInfo, ok := request.RequestInfoFrom(ctx)
    40  		if !ok {
    41  			handleError(w, req, http.StatusInternalServerError, nil, "no RequestInfo found in context, handler chain must be wrong")
    42  			return
    43  		}
    44  
    45  		if watchVerbs.Has(requestInfo.Verb) {
    46  			handler.ServeHTTP(w, req)
    47  			return
    48  		}
    49  
    50  		req = req.WithContext(request.WithLatencyTrackers(ctx))
    51  		w = responsewriter.WrapForHTTP1Or2(&writeLatencyTracker{
    52  			ResponseWriter: w,
    53  			ctx:            req.Context(),
    54  		})
    55  
    56  		handler.ServeHTTP(w, req)
    57  	})
    58  }
    59  
    60  var _ http.ResponseWriter = &writeLatencyTracker{}
    61  var _ responsewriter.UserProvidedDecorator = &writeLatencyTracker{}
    62  
    63  type writeLatencyTracker struct {
    64  	http.ResponseWriter
    65  	ctx context.Context
    66  }
    67  
    68  func (wt *writeLatencyTracker) Unwrap() http.ResponseWriter {
    69  	return wt.ResponseWriter
    70  }
    71  
    72  func (wt *writeLatencyTracker) Write(bs []byte) (int, error) {
    73  	startedAt := time.Now()
    74  	defer func() {
    75  		request.TrackResponseWriteLatency(wt.ctx, time.Since(startedAt))
    76  	}()
    77  
    78  	return wt.ResponseWriter.Write(bs)
    79  }