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Add kubernetes_leaderelection provider (elastic#24913)
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20 changes: 20 additions & 0 deletions
20
x-pack/elastic-agent/pkg/composable/providers/kubernetesleaderelection/config.go
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// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one | ||
// or more contributor license agreements. Licensed under the Elastic License; | ||
// you may not use this file except in compliance with the Elastic License. | ||
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// TODO review the need for this | ||
// +build linux darwin windows | ||
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package kubernetesleaderelection | ||
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// Config for kubernetes_leaderelection provider | ||
type Config struct { | ||
KubeConfig string `config:"kube_config"` | ||
// Name of the leaderelection lease | ||
LeaderLease string `config:"leader_lease"` | ||
} | ||
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// InitDefaults initializes the default values for the config. | ||
func (c *Config) InitDefaults() { | ||
c.LeaderLease = "elastic-agent-cluster-leader" | ||
} |
148 changes: 148 additions & 0 deletions
148
...stic-agent/pkg/composable/providers/kubernetesleaderelection/kubernetes_leaderelection.go
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// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one | ||
// or more contributor license agreements. Licensed under the Elastic License; | ||
// you may not use this file except in compliance with the Elastic License. | ||
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package kubernetesleaderelection | ||
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import ( | ||
"context" | ||
"os" | ||
"time" | ||
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" | ||
"k8s.io/client-go/tools/leaderelection" | ||
"k8s.io/client-go/tools/leaderelection/resourcelock" | ||
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"github.com/elastic/beats/v7/libbeat/common/kubernetes" | ||
"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/agent/application/info" | ||
"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/agent/errors" | ||
"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable" | ||
"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/config" | ||
corecomp "github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/core/composable" | ||
"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/core/logger" | ||
) | ||
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func init() { | ||
composable.Providers.AddContextProvider("kubernetes_leaderelection", ContextProviderBuilder) | ||
} | ||
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type contextProvider struct { | ||
logger *logger.Logger | ||
config *Config | ||
comm corecomp.ContextProviderComm | ||
leaderElection *leaderelection.LeaderElectionConfig | ||
cancelLeaderElection context.CancelFunc | ||
} | ||
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// ContextProviderBuilder builds the provider. | ||
func ContextProviderBuilder(logger *logger.Logger, c *config.Config) (corecomp.ContextProvider, error) { | ||
var cfg Config | ||
if c == nil { | ||
c = config.New() | ||
} | ||
err := c.Unpack(&cfg) | ||
if err != nil { | ||
return nil, errors.New(err, "failed to unpack configuration") | ||
} | ||
return &contextProvider{logger, &cfg, nil, nil, nil}, nil | ||
} | ||
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// Run runs the leaderelection provider. | ||
func (p *contextProvider) Run(comm corecomp.ContextProviderComm) error { | ||
client, err := kubernetes.GetKubernetesClient(p.config.KubeConfig) | ||
if err != nil { | ||
// info only; return nil (do nothing) | ||
p.logger.Debugf("Kubernetes leaderelection provider skipped, unable to connect: %s", err) | ||
return nil | ||
} | ||
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agentInfo, err := info.NewAgentInfo() | ||
if err != nil { | ||
return err | ||
} | ||
var id string | ||
podName, found := os.LookupEnv("POD_NAME") | ||
if found { | ||
id = "elastic-agent-leader-" + podName | ||
} else { | ||
id = "elastic-agent-leader-" + agentInfo.AgentID() | ||
} | ||
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ns, err := kubernetes.InClusterNamespace() | ||
if err != nil { | ||
ns = "default" | ||
} | ||
lease := metav1.ObjectMeta{ | ||
Name: p.config.LeaderLease, | ||
Namespace: ns, | ||
} | ||
metaUID := lease.GetObjectMeta().GetUID() | ||
p.leaderElection = &leaderelection.LeaderElectionConfig{ | ||
Lock: &resourcelock.LeaseLock{ | ||
LeaseMeta: lease, | ||
Client: client.CoordinationV1(), | ||
LockConfig: resourcelock.ResourceLockConfig{ | ||
Identity: id, | ||
}, | ||
}, | ||
ReleaseOnCancel: true, | ||
LeaseDuration: 15 * time.Second, | ||
RenewDeadline: 10 * time.Second, | ||
RetryPeriod: 2 * time.Second, | ||
Callbacks: leaderelection.LeaderCallbacks{ | ||
OnStartedLeading: func(ctx context.Context) { | ||
p.logger.Debugf("leader election lock GAINED, id %v", id) | ||
p.startLeading(string(metaUID)) | ||
}, | ||
OnStoppedLeading: func() { | ||
p.logger.Debugf("leader election lock LOST, id %v", id) | ||
p.stopLeading(string(metaUID)) | ||
}, | ||
}, | ||
} | ||
ctx, cancel := context.WithCancel(context.TODO()) | ||
p.cancelLeaderElection = cancel | ||
p.comm = comm | ||
p.startLeaderElector(ctx) | ||
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return nil | ||
} | ||
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// startLeaderElector starts a Leader Elector in the background with the provided config | ||
func (p *contextProvider) startLeaderElector(ctx context.Context) { | ||
le, err := leaderelection.NewLeaderElector(*p.leaderElection) | ||
if err != nil { | ||
p.logger.Errorf("error while creating Leader Elector: %v", err) | ||
} | ||
p.logger.Debugf("Starting Leader Elector") | ||
go le.Run(ctx) | ||
} | ||
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func (p *contextProvider) startLeading(metaUID string) { | ||
mapping := map[string]interface{}{ | ||
"leader": true, | ||
} | ||
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err := p.comm.Set(mapping) | ||
if err != nil { | ||
p.logger.Errorf("Failed updating leaderelection status to leader TRUE: %s", err) | ||
} | ||
} | ||
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func (p *contextProvider) stopLeading(metaUID string) { | ||
mapping := map[string]interface{}{ | ||
"leader": false, | ||
} | ||
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err := p.comm.Set(mapping) | ||
if err != nil { | ||
p.logger.Errorf("Failed updating leaderelection status to leader FALSE: %s", err) | ||
} | ||
} | ||
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// Stop signals the stop channel to force the leader election loop routine to stop. | ||
func (p *contextProvider) Stop() { | ||
if p.cancelLeaderElection != nil { | ||
p.cancelLeaderElection() | ||
} | ||
} |