4ace7c7d77
This also happens without gRPC proxy. Fix panic when gRPC proxy leader watcher is restored: ``` go test -v -tags cluster_proxy -cpu 4 -race -run TestV3WatchRestoreSnapshotUnsync === RUN TestV3WatchRestoreSnapshotUnsync panic: watcher minimum revision 9223372036854775805 should not exceed current revision 16 goroutine 156 [running]: github.com/coreos/etcd/mvcc.(*watcherGroup).chooseAll(0xc4202b8720, 0x10, 0xffffffffffffffff, 0x1) /home/gyuho/go/src/github.com/coreos/etcd/mvcc/watcher_group.go:242 +0x3b5 github.com/coreos/etcd/mvcc.(*watcherGroup).choose(0xc4202b8720, 0x200, 0x10, 0xffffffffffffffff, 0xc420253378, 0xc420253378) /home/gyuho/go/src/github.com/coreos/etcd/mvcc/watcher_group.go:225 +0x289 github.com/coreos/etcd/mvcc.(*watchableStore).syncWatchers(0xc4202b86e0, 0x0) /home/gyuho/go/src/github.com/coreos/etcd/mvcc/watchable_store.go:340 +0x237 github.com/coreos/etcd/mvcc.(*watchableStore).syncWatchersLoop(0xc4202b86e0) /home/gyuho/go/src/github.com/coreos/etcd/mvcc/watchable_store.go:214 +0x280 created by github.com/coreos/etcd/mvcc.newWatchableStore /home/gyuho/go/src/github.com/coreos/etcd/mvcc/watchable_store.go:90 +0x477 exit status 2 FAIL github.com/coreos/etcd/integration 2.551s ``` gRPC proxy spawns a watcher with a key "proxy-namespace__lostleader" and watch revision "int64(math.MaxInt64 - 2)" to detect leader loss. But, when the partitioned node restores, this watcher triggers panic with "watcher minimum revision ... should not exceed current ...". This check was added a long time ago, by my PR, when there was no gRPC proxy: https://github.com/coreos/etcd/pull/4043#discussion_r48457145 > we can remove this checking actually. it is impossible for a unsynced watching to have a future rev. or we should just panic here. However, now it's possible that a unsynced watcher has a future revision, when it was moved from a synced watcher group through restore operation. This PR adds "restore" flag to indicate that a watcher was moved from the synced watcher group with restore operation. Otherwise, the watcher with future revision in an unsynced watcher group would still panic. Example logs with future revision watcher from restore operation: ``` {"level":"info","ts":1527196358.9057755,"caller":"mvcc/watcher_group.go:261","msg":"choosing future revision watcher from restore operation","watch-key":"proxy-namespace__lostleader","watch-revision":9223372036854775805,"current-revision":16} {"level":"info","ts":1527196358.910349,"caller":"mvcc/watcher_group.go:261","msg":"choosing future revision watcher from restore operation","watch-key":"proxy-namespace__lostleader","watch-revision":9223372036854775805,"current-revision":16} ``` Signed-off-by: Gyuho Lee <gyuhox@gmail.com>
etcd
Note: The master branch may be in an unstable or even broken state during development. Please use releases instead of the master branch in order to get stable binaries.
the etcd v2 documentation has moved
etcd is a distributed reliable key-value store for the most critical data of a distributed system, with a focus on being:
- Simple: well-defined, user-facing API (gRPC)
- Secure: automatic TLS with optional client cert authentication
- Fast: benchmarked 10,000 writes/sec
- Reliable: properly distributed using Raft
etcd is written in Go and uses the Raft consensus algorithm to manage a highly-available replicated log.
etcd is used in production by many companies, and the development team stands behind it in critical deployment scenarios, where etcd is frequently teamed with applications such as Kubernetes, fleet, locksmith, vulcand, Doorman, and many others. Reliability is further ensured by rigorous testing.
See etcdctl for a simple command line client.
Getting started
Getting etcd
The easiest way to get etcd is to use one of the pre-built release binaries which are available for OSX, Linux, Windows, rkt, and Docker. Instructions for using these binaries are on the GitHub releases page.
For those wanting to try the very latest version, build the latest version of etcd from the master branch. This first needs Go installed (version 1.8+ is required). 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:
ETCDCTL_API=3 etcdctl put mykey "this is awesome"
ETCDCTL_API=3 etcdctl get mykey
That's it! etcd is now running and serving client requests. For more
etcd TCP ports
The official etcd ports are 2379 for client requests, and 2380 for peer communication.
Running a local etcd cluster
First install goreman, which manages Procfile-based applications.
Our Procfile script will set up a local example cluster. 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.
Every cluster member and proxy accepts key value reads and key value writes.
Running etcd on Kubernetes
To run an etcd cluster on Kubernetes, try etcd operator.
Next steps
Now it's time to dig into the full etcd API and other guides.
- Read the full documentation.
- Explore the full gRPC 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.
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.
Reporting bugs
See reporting bugs for details about reporting any issues.
License
etcd is under the Apache 2.0 license. See the LICENSE file for details.