Add kubernetes_leaderelection provider #24913
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| Original file line number | Diff line number | Diff line change |
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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" | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,148 @@ | ||
| // 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() | ||
|
Contributor
There was a problem hiding this comment. Should there also be a configuration value for this? Might want to run it on a different namespace?
Member
Author
There was a problem hiding this comment. The convention here is that we will create the So I think we should keep it as is and not expose this as an option to the user. |
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| 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) | ||
| } | ||
|
jsoriano marked this conversation as resolved.
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| } | ||
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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() | ||
| } | ||
| } | ||
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So by default running Elastic Agent this is off. Is that the behavior we want? Being that will require a specific setting in the
providerstop-level key, and not something that could then be used by Fleet at the moment.I think that we should have this enabled by default, by having it have a default value.
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Agree, I will add it.