k8s.io/apiserver@v0.31.1/pkg/server/filters/watch_termination.go (about)

     1  /*
     2  Copyright 2023 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  	"errors"
    21  	"net/http"
    22  
    23  	"k8s.io/apiserver/pkg/endpoints/handlers/responsewriters"
    24  	apirequest "k8s.io/apiserver/pkg/endpoints/request"
    25  	"k8s.io/klog/v2"
    26  )
    27  
    28  func WithWatchTerminationDuringShutdown(handler http.Handler, termination apirequest.ServerShutdownSignal, wg RequestWaitGroup) http.Handler {
    29  	if termination == nil || wg == nil {
    30  		klog.Warningf("watch termination during shutdown not attached to the handler chain")
    31  		return handler
    32  	}
    33  	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
    34  		ctx := req.Context()
    35  		requestInfo, ok := apirequest.RequestInfoFrom(ctx)
    36  		if !ok {
    37  			// if this happens, the handler chain isn't setup correctly because there is no request info
    38  			responsewriters.InternalError(w, req, errors.New("no RequestInfo found in the context"))
    39  			return
    40  		}
    41  		if !watchVerbs.Has(requestInfo.Verb) {
    42  			handler.ServeHTTP(w, req)
    43  			return
    44  		}
    45  
    46  		if err := wg.Add(1); err != nil {
    47  			// When apiserver is shutting down, signal clients to retry
    48  			// There is a good chance the client hit a different server, so a tight retry is good for client responsiveness.
    49  			waitGroupWriteRetryAfterToResponse(w)
    50  			return
    51  		}
    52  
    53  		// attach ServerShutdownSignal to the watch request so that the
    54  		// watch handler loop can return as soon as the server signals
    55  		// that it is shutting down.
    56  		ctx = apirequest.WithServerShutdownSignal(req.Context(), termination)
    57  		req = req.WithContext(ctx)
    58  
    59  		defer wg.Done()
    60  		handler.ServeHTTP(w, req)
    61  	})
    62  }