istio

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/*
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Copyright 2016 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 k8sresourcelock
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import (
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	"context"
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	"fmt"
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	"time"
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	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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	"k8s.io/apimachinery/pkg/runtime"
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	clientset "k8s.io/client-go/kubernetes"
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	coordinationv1 "k8s.io/client-go/kubernetes/typed/coordination/v1"
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	corev1 "k8s.io/client-go/kubernetes/typed/core/v1"
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	restclient "k8s.io/client-go/rest"
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)
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const (
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	LeaderElectionRecordAnnotationKey = "control-plane.alpha.kubernetes.io/leader"
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	EndpointsResourceLock             = "endpoints"
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	ConfigMapsResourceLock            = "configmaps"
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	LeasesResourceLock                = "leases"
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	EndpointsLeasesResourceLock       = "endpointsleases"
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	ConfigMapsLeasesResourceLock      = "configmapsleases"
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)
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// LeaderElectionRecord is the record that is stored in the leader election annotation.
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// This information should be used for observational purposes only and could be replaced
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// with a random string (e.g. UUID) with only slight modification of this code.
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// TODO(mikedanese): this should potentially be versioned
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type LeaderElectionRecord struct {
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	// HolderIdentity is the ID that owns the lease. If empty, no one owns this lease and
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	// all callers may acquire. Versions of this library prior to Kubernetes 1.14 will not
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	// attempt to acquire leases with empty identities and will wait for the full lease
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	// interval to expire before attempting to reacquire. This value is set to empty when
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	// a client voluntarily steps down.
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	HolderIdentity string `json:"holderIdentity"`
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	// HolderKey is the Key of the lease owner. This may be empty if a key is not set.
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	HolderKey            string      `json:"holderKey"`
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	LeaseDurationSeconds int         `json:"leaseDurationSeconds"`
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	AcquireTime          metav1.Time `json:"acquireTime"`
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	RenewTime            metav1.Time `json:"renewTime"`
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	LeaderTransitions    int         `json:"leaderTransitions"`
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}
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// EventRecorder records a change in the ResourceLock.
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type EventRecorder interface {
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	Eventf(obj runtime.Object, eventType, reason, message string, args ...any)
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}
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// ResourceLockConfig common data that exists across different
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// resource locks
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type ResourceLockConfig struct {
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	// Identity is the unique string identifying a lease holder across
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	// all participants in an election.
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	Identity string
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	// Key is a user-defined value used to indicate how high priority this lock
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	// have. Other locks may steal the lock from us if they believe their key
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	// has a higher priority.
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	Key string
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	// EventRecorder is optional.
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	EventRecorder EventRecorder
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}
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// Interface offers a common interface for locking on arbitrary
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// resources used in leader election.  The Interface is used
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// to hide the details on specific implementations in order to allow
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// them to change over time.  This interface is strictly for use
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// by the leaderelection code.
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type Interface interface {
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	// Get returns the LeaderElectionRecord
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	Get(ctx context.Context) (*LeaderElectionRecord, []byte, error)
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	// Create attempts to create a LeaderElectionRecord
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	Create(ctx context.Context, ler LeaderElectionRecord) error
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	// Update will update and existing LeaderElectionRecord
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	Update(ctx context.Context, ler LeaderElectionRecord) error
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	// RecordEvent is used to record events
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	RecordEvent(string)
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	// Identity will return the locks Identity
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	Identity() string
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	Key() string
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	// Describe is used to convert details on current resource lock
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	// into a string
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	Describe() string
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}
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// Manufacture will create a lock of a given type according to the input parameters
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// nolint: lll
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func New(lockType string, ns string, name string, coreClient corev1.CoreV1Interface, coordinationClient coordinationv1.CoordinationV1Interface, rlc ResourceLockConfig) (Interface, error) {
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	endpointsLock := &EndpointsLock{
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		EndpointsMeta: metav1.ObjectMeta{
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			Namespace: ns,
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			Name:      name,
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		},
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		Client:     coreClient,
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		LockConfig: rlc,
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	}
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	configmapLock := &ConfigMapLock{
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		ConfigMapMeta: metav1.ObjectMeta{
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			Namespace: ns,
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			Name:      name,
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		},
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		Client:     coreClient,
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		LockConfig: rlc,
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	}
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	leaseLock := &LeaseLock{
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		LeaseMeta: metav1.ObjectMeta{
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			Namespace: ns,
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			Name:      name,
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		},
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		Client:     coordinationClient,
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		LockConfig: rlc,
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	}
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	switch lockType {
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	case EndpointsResourceLock:
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		return endpointsLock, nil
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	case ConfigMapsResourceLock:
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		return configmapLock, nil
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	case LeasesResourceLock:
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		return leaseLock, nil
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	case EndpointsLeasesResourceLock:
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		return &MultiLock{
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			Primary:   endpointsLock,
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			Secondary: leaseLock,
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		}, nil
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	case ConfigMapsLeasesResourceLock:
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		return &MultiLock{
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			Primary:   configmapLock,
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			Secondary: leaseLock,
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		}, nil
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	default:
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		return nil, fmt.Errorf("invalid lock-type %s", lockType)
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	}
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}
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// NewFromKubeconfig will create a lock of a given type according to the input parameters.
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// Timeout set for a client used to contact to Kubernetes should be lower than
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// RenewDeadline to keep a single hung request from forcing a leader loss.
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// Setting it to max(time.Second, RenewDeadline/2) as a reasonable heuristic.
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// nolint: lll
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func NewFromKubeconfig(lockType string, ns string, name string, rlc ResourceLockConfig, kubeconfig *restclient.Config, renewDeadline time.Duration) (Interface, error) {
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	// shallow copy, do not modify the kubeconfig
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	config := *kubeconfig
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	timeout := renewDeadline / 2
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	if timeout < time.Second {
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		timeout = time.Second
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	}
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	config.Timeout = timeout
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	leaderElectionClient := clientset.NewForConfigOrDie(restclient.AddUserAgent(&config, "leader-election"))
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	return New(lockType, ns, name, leaderElectionClient.CoreV1(), leaderElectionClient.CoordinationV1(), rlc)
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}
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