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https://github.com/ahmagdy/leaderelection
A go leader election module based on ETCD that can be used to track leader ownership
https://github.com/ahmagdy/leaderelection
etcd etcdv3 go golang leader-election
Last synced: about 1 month ago
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A go leader election module based on ETCD that can be used to track leader ownership
- Host: GitHub
- URL: https://github.com/ahmagdy/leaderelection
- Owner: ahmagdy
- License: apache-2.0
- Created: 2022-05-15T12:51:09.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2022-05-27T17:45:27.000Z (over 2 years ago)
- Last Synced: 2024-11-06T23:33:23.543Z (3 months ago)
- Topics: etcd, etcdv3, go, golang, leader-election
- Language: Go
- Homepage:
- Size: 60.5 KB
- Stars: 1
- Watchers: 2
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# etcd-leaderelection
A go leader election module that can be used to track leader changes.
### Install
```bash
go get -u github.com/ahmagdy/leaderelection
```
### Use case:
This package is intended to be used when multiple instances are running of service, and only a single instance can be the leader, or a single instance can do a specific job.
### Example:
It's mostly intended for services built on top of a framework that supports app lifecycle. e.g. [Uber fx](https://github.com/uber-go/fx).
```go
leaderElection := leaderelection.New(etcdClient, zapLogger, instanceName, watcher)
fx.Invoke(func(lc fx.Lifecycle) {
lc.Append(fx.Hook{
OnStart: func(context.Context) error { return leaderElection.Start(ctx) },
OnStop: func(context.Context) error { return leaderElection.Stop(ctx) },
})
})
```
##### Without lifecycle support:
```go
func run(ctx context.Context, logger *zap.Logger, instanceName string) error {
etcdClient, err := newETCDClient(etcdSeedHostPorts)
if err != nil {
return nil
}
watcher := &WatcherService{logger: logger}
leaderElection, err := leaderelection.New(etcdClient, logger, instanceName, watcher)
if err != nil {
return err
}
if err := leaderElection.Start(ctx); err != nil {
return fmt.Errorf("failed to start leader election: %w", err)
}
defer func() {
if err := leaderElection.Stop(ctx); err != nil {
logger.Error("failed to stop leader election", zap.Error(err))
}
}()
}
```
#### Watcher interface to act on leadership changes
I tried to keep the interface minimal without fancy options.
Feel free to contribute or open a ticket if you feel like it's missing an event or can be extended.
```go
var _ leaderelection.EventsWatcher = (*WatcherService)(nil)
type WatcherService struct {
logger *zap.Logger
}
func (w *WatcherService) OnGainedLeadership() {
w.logger.Info("I am the new leader")
}
func (w *WatcherService) OnLostLeadership() {
w.logger.Info("I am no longer the leader")
}
```
Please check the `/example` package for more go examples.
## License:
[Apache License 2.0](https://github.com/ahmagdy/leaderelection/blob/main/LICENSE)