istio

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/*
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Copyright 2015 The Kubernetes 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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    http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package k8sleaderelection
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import (
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	"net/http"
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	"sync"
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	"time"
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)
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// HealthzAdaptor associates the /healthz endpoint with the LeaderElection object.
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// It helps deal with the /healthz endpoint being set up prior to the LeaderElection.
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// This contains the code needed to act as an adaptor between the leader
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// election code the health check code. It allows us to provide health
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// status about the leader election. Most specifically about if the leader
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// has failed to renew without exiting the process. In that case we should
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// report not healthy and rely on the kubelet to take down the process.
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type HealthzAdaptor struct {
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	pointerLock sync.Mutex
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	le          *LeaderElector
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	timeout     time.Duration
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}
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// Name returns the name of the health check we are implementing.
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func (l *HealthzAdaptor) Name() string {
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	return "leaderElection"
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}
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// Check is called by the healthz endpoint handler.
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// It fails (returns an error) if we own the lease but had not been able to renew it.
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func (l *HealthzAdaptor) Check(req *http.Request) error {
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	l.pointerLock.Lock()
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	defer l.pointerLock.Unlock()
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	if l.le == nil {
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		return nil
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	}
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	return l.le.Check(l.timeout)
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}
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// SetLeaderElection ties a leader election object to a HealthzAdaptor
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func (l *HealthzAdaptor) SetLeaderElection(le *LeaderElector) {
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	l.pointerLock.Lock()
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	defer l.pointerLock.Unlock()
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	l.le = le
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}
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// NewLeaderHealthzAdaptor creates a basic healthz adaptor to monitor a leader election.
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// timeout determines the time beyond the lease expiry to be allowed for timeout.
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// checks within the timeout period after the lease expires will still return healthy.
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func NewLeaderHealthzAdaptor(timeout time.Duration) *HealthzAdaptor {
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	result := &HealthzAdaptor{
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		timeout: timeout,
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	}
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	return result
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}
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