113 lines
2.8 KiB
Go
113 lines
2.8 KiB
Go
// +build kvdb_etcd
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package cluster
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import (
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"context"
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"time"
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"github.com/lightningnetwork/lnd/channeldb/kvdb/etcd"
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"go.etcd.io/etcd/clientv3"
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"go.etcd.io/etcd/clientv3/concurrency"
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"go.etcd.io/etcd/clientv3/namespace"
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"go.etcd.io/etcd/pkg/transport"
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)
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const (
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// etcdConnectionTimeout is the timeout until successful connection to
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// the etcd instance.
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etcdConnectionTimeout = 10 * time.Second
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)
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// Enforce that etcdLeaderElector implements the LeaderElector interface.
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var _ LeaderElector = (*etcdLeaderElector)(nil)
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// etcdLeaderElector is an implemetation of LeaderElector using etcd as the
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// election governor.
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type etcdLeaderElector struct {
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id string
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ctx context.Context
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cli *clientv3.Client
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session *concurrency.Session
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election *concurrency.Election
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}
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// newEtcdLeaderElector constructs a new etcdLeaderElector.
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func newEtcdLeaderElector(ctx context.Context, id, electionPrefix string,
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cfg *etcd.Config) (*etcdLeaderElector, error) {
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clientCfg := clientv3.Config{
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Context: ctx,
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Endpoints: []string{cfg.Host},
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DialTimeout: etcdConnectionTimeout,
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Username: cfg.User,
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Password: cfg.Pass,
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}
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if !cfg.DisableTLS {
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tlsInfo := transport.TLSInfo{
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CertFile: cfg.CertFile,
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KeyFile: cfg.KeyFile,
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InsecureSkipVerify: cfg.InsecureSkipVerify,
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}
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tlsConfig, err := tlsInfo.ClientConfig()
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if err != nil {
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return nil, err
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}
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clientCfg.TLS = tlsConfig
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}
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cli, err := clientv3.New(clientCfg)
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if err != nil {
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log.Errorf("Unable to connect to etcd: %v", err)
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return nil, err
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}
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// Apply the namespace.
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cli.KV = namespace.NewKV(cli.KV, cfg.Namespace)
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cli.Watcher = namespace.NewWatcher(cli.Watcher, cfg.Namespace)
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cli.Lease = namespace.NewLease(cli.Lease, cfg.Namespace)
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log.Infof("Applied namespace to leader elector: %v", cfg.Namespace)
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session, err := concurrency.NewSession(cli)
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if err != nil {
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log.Errorf("Unable to start new leader election session: %v",
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err)
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return nil, err
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}
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return &etcdLeaderElector{
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id: id,
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ctx: ctx,
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cli: cli,
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session: session,
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election: concurrency.NewElection(
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session, electionPrefix,
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),
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}, nil
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}
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// Leader returns the leader value for the current election.
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func (e *etcdLeaderElector) Leader(ctx context.Context) (string, error) {
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resp, err := e.election.Leader(ctx)
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if err != nil {
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return "", err
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}
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return string(resp.Kvs[0].Value), nil
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}
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// Campaign will start a new leader election campaign. Campaign will block until
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// the elector context is canceled or the the caller is elected as the leader.
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func (e *etcdLeaderElector) Campaign(ctx context.Context) error {
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return e.election.Campaign(ctx, e.id)
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}
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// Resign resigns the leader role allowing other election members to take
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// the place.
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func (e *etcdLeaderElector) Resign() error {
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return e.election.Resign(context.Background())
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}
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