Scalingo / go-etcd-cron

Library to run a distributed cron-like task scheduler

Go Etcd Cron v1.3.3

This package has been based on the project https://github.com/robfig/cron

Goal

This package aims at implementing a distributed and fault tolerant cron in order to:

• Run an identical process on several hosts
• Each of these process instantiate a cron with the same rules
• Ensure only one of these processes executes an iteration of a job

Etcd Initialization

By default the library creates an etcd client on 127.0.0.1:2379

c, _ := etcdcron.NewEtcdMutexBuilder(clientv3.Config{
  Endpoints: []string{"etcd-host1:2379", "etcd-host2:2379"},
})
cron, _ := etcdcron.New(WithEtcdMutexBuilder(c))
cron.AddJob(Job{
  Name: "job0",
  Rhythm: "*/2 * * * * *",
  Func: func(ctx context.Context) error {
    // Handler
  },
})

Error Handling

errorsHandler := func(ctx context.Context, job etcdcron.Job, err error) {
  // Do something with the error which happened during 'job'
}
etcdErrorsHandler := func(ctx context.Context, job etcdcron.Job, err error) {
  // Do something with the error which happened at the time of the execution of 'job'
  // But locking mecanism fails because of etcd error
}

cron, _ := etcdcron.New(
  WithErrorsHandler(errorsHandler),
  WithEtcdErrorsHandler(etcdErrorsHandler),
)

cron.AddJob(Job{
  Name: "job0",
  Rhythm: "*/2 * * * * *",
  Func: func(ctx context.Context) error {
    // Handler
  },
})

Release a New Version

Bump new version number in CHANGELOG.md and README.md.

Commit, tag and create a new release:

version="1.3.3"

git switch --create release/${version}
git add CHANGELOG.md README.md
git commit --message="Bump v${version}"
git push --set-upstream origin release/${version}
gh pr create --reviewer=EtienneM --title "$(git log -1 --pretty=%B)"

Once the pull request merged, you can tag the new release.

git tag v${version}
git push origin master v${version}
gh release create v${version}

The title of the release should be the version number and the text of the release is the same as the changelog.