# etcd

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![etcd Logo](logos/etcd-horizontal-color.png)

etcd is a distributed, consistent key value store for shared configuration and service discovery with a focus on being:

* *Simple*: curl'able user facing API (HTTP+JSON)
* *Secure*: optional SSL client cert authentication
* *Fast*: benchmarked 1000s of writes/s per instance
* *Reliable*: properly distributed using Raft

etcd is written in Go and uses the [Raft][raft] consensus algorithm to manage a highly-available replicated log.

See [etcdctl][etcdctl] for a simple command line client.
Or feel free to just use curl, as in the examples below.

[zookeeper]: http://zookeeper.apache.org/
[doozer]: https://github.com/ha/doozerd
[raft]: http://raftconsensus.github.io/
[etcdctl]: https://github.com/coreos/etcd/tree/master/etcdctl

If you're considering etcd for production use, please see: [production-ready.md](./Documentation/production-ready.md)

## Getting Started

### Getting etcd

The latest release and setup instructions are available at [GitHub][github-release].

You can build a latest etcd from master branch. All development occurs on the master branch which includes new features and bug fixes.

Bug fixes should target the master branch and ported to the appropriate release branch as described in the [branch management](./Documentation/branch_management.md) guide.

[github-release]: https://github.com/coreos/etcd/releases/

### Running etcd

First start a single-member cluster of etcd:

```sh
./bin/etcd
```

This will bring up etcd listening on port 2379 for client communication and on port 2380 for server-to-server communication.

Next, let's set a single key, and then retrieve it:

```
curl -L http://127.0.0.1:2379/v2/keys/mykey -XPUT -d value="this is awesome"
curl -L http://127.0.0.1:2379/v2/keys/mykey
```

You have successfully started an etcd and written a key to the store.

### Running local etcd cluster

First install [goreman](https://github.com/mattn/goreman), which manages Procfile-based applications.

Our [Procfile script](./Procfile) will set up a local example cluster. You can start it with:

```sh
goreman start
```

This will bring up 3 etcd members `infra1`, `infra2` and `infra3` and etcd proxy `proxy`, which runs locally and composes a cluster.

You can write a key to the cluster and retrieve the value back from any member or proxy.

### Next Steps

Now it's time to dig into the full etcd API and other guides.

- Explore the full [API][api].
- Set up a [multi-machine cluster][clustering].
- Learn the [config format, env variables and flags][configuration].
- Find [language bindings and tools][libraries-and-tools].
- Use TLS to [secure an etcd cluster][security].
- [Tune etcd][tuning].
- [Upgrade from 0.4.6 to 2.0.0][upgrade].

[api]: ./Documentation/api.md
[clustering]: ./Documentation/clustering.md
[configuration]: ./Documentation/configuration.md
[libraries-and-tools]: ./Documentation/libraries-and-tools.md
[security]: ./Documentation/security.md
[tuning]: ./Documentation/tuning.md
[upgrade]: ./Documentation/0_4_migration_tool.md

## Contact

- Mailing list: [etcd-dev](https://groups.google.com/forum/?hl=en#!forum/etcd-dev)
- IRC: #[coreos](irc://irc.freenode.org:6667/#coreos) on freenode.org
- Planning/Roadmap: [milestones](https://github.com/coreos/etcd/milestones)
- Bugs: [issues](https://github.com/coreos/etcd/issues)

## Contributing

See [CONTRIBUTING](CONTRIBUTING.md) for details on submitting patches and the contribution workflow.

## Project Details

### Versioning

#### Service Versioning

etcd uses [semantic versioning](http://semver.org)
New minor versions may add additional features to the API.

You can get the version of etcd by issuing a request to /version:

```sh
curl -L http://127.0.0.1:2379/version
```

#### API Versioning

The `v2` API responses should not change after the 2.0.0 release but new features will be added over time.

#### 32-bit systems

etcd has known issues on 32-bit systems due to a bug in the Go runtime. See #[358][358] for more information.

[358]: https://github.com/coreos/etcd/issues/358

### License

etcd is under the Apache 2.0 license. See the [LICENSE](LICENSE) file for details.