6c9e876d7a
This method uses raft status exposed at /debug/varz to determine the health of the cluster. It uses whether commit index increases to determine the cluster health, and uses whether match index increases to determine the member health. This could fix the bug #2711 that fails to detect follower is unhealthy because it doesn't rely on whether message in long-polling connection is sent. This health check is stricter than the old one, and reflects the situation that whether followers are healthy in the view of the leader. One example is that if the follower is receiving the snapshot, it will turns out to be unhealthy because it doesn't move forward. `etcdctl cluster-health` will reflect the healthy view in the raft level, while connectivity checks reflects the healthy view in transport level.
etcd
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 consensus algorithm to manage a highly-available replicated log.
See etcdctl for a simple command line client. Or feel free to just use curl, as in the examples below.
If you're considering etcd for production use, please see: production-ready.md
Getting Started
Getting etcd
The easiest way to get etcd is to install one of the pre-built binaries from the tagged releases: instructions are available on GitHub.
For those wanting to try the very latest version, you can build the latest version of etcd from the master branch.
All development occurs on master, including new features and bug fixes.
Bug fixes are first targeted at master and subsequently ported to release branches, as described in the branch management guide.
Running etcd
First start a single-member cluster of etcd:
./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, which manages Procfile-based applications.
Our Procfile script will set up a local example cluster. You can start it with:
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.
- Set up a multi-machine cluster.
- Learn the config format, env variables and flags.
- Find language bindings and tools.
- Use TLS to secure an etcd cluster.
- Tune etcd.
- Upgrade from 0.4.6 to 2.0.0.
Contact
- Mailing list: etcd-dev
- IRC: #etcd on freenode.org
- Planning/Roadmap: milestones, roadmap
- Bugs: issues
Contributing
See CONTRIBUTING for details on submitting patches and the contribution workflow.
Project Details
Versioning
Service Versioning
etcd uses semantic versioning New minor versions may add additional features to the API.
You can get the version of etcd by issuing a request to /version:
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 for more information.
License
etcd is under the Apache 2.0 license. See the LICENSE file for details.