Tree @lintian-fixes/main (Download .tar.gz)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 | # Leadership: Distributed Leader Election for Clustered Environments. Leadership is a library for a cluster leader election on top of a distributed Key/Value store. It is built using the `docker/libkv` library and is designed to work across multiple storage backends. You can use `leadership` with `Consul`, `etcd` and `Zookeeper`. ```go // Create a store using pkg/store. client, err := store.NewStore("consul", []string{"127.0.0.1:8500"}, &store.Config{}) if err != nil { panic(err) } underwood := leadership.NewCandidate(client, "service/swarm/leader", "underwood", 15*time.Second) electedCh, _ := underwood.RunForElection() for isElected := range electedCh { // This loop will run every time there is a change in our leadership // status. if isElected { // We won the election - we are now the leader. // Let's do leader stuff, for example, sleep for a while. log.Printf("I won the election! I'm now the leader") time.Sleep(10 * time.Second) // Tired of being a leader? You can resign anytime. candidate.Resign() } else { // We lost the election but are still running for leadership. // `elected == false` is the default state and is the first event // we'll receive from the channel. After a successful election, // this event can get triggered if someone else steals the // leadership or if we resign. log.Printf("Lost the election, let's try another time") } } ``` It is possible to follow an election in real-time and get notified whenever there is a change in leadership: ```go follower := leadership.NewFollower(client, "service/swarm/leader") leaderCh, _ := follower.FollowElection() for leader := range leaderCh { // Leader is a string containing the value passed to `NewCandidate`. log.Printf("%s is now the leader", leader) } log.Fatal("Cannot follow the election, store is probably down") // Recovery code or exit ``` A typical use case for this is to be able to always send requests to the current leader. ## Fault tolerance Leadership returns an error channel for Candidates and Followers that you can use to be resilient to failures. For example, if the watch on the leader key fails because the store becomes unavailable, you can retry the process later. ```go func participate() { // Create a store using pkg/store. client, err := store.NewStore("consul", []string{"127.0.0.1:8500"}, &store.Config{}) if err != nil { panic(err) } waitTime := 10 * time.Second underwood := leadership.NewCandidate(client, "service/swarm/leader", "underwood", 15*time.Second) go func() { for { run(underwood) time.Sleep(waitTime) // retry } }() } func run(candidate *leadership.Candidate) { electedCh, errCh := candidate.RunForElection() for { select { case isElected := <-electedCh: if isElected { // Do something } else { // Do something else } case err := <-errCh: log.Error(err) return } } } ``` ## License leadership is licensed under the Apache License, Version 2.0. See [LICENSE](LICENSE) for the full license text. |
Commit History @lintian-fixes/main
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- point Vcs-* urls to salsa.debian.org aviau 6 years ago
- Add me to uploaders Tim Potter 7 years ago
- Finialise changelog for upload Tim Potter 7 years ago
- Merge tag 'upstream/0.1.0' Tim Potter 7 years ago
- New upstream version 0.1.0 Tim Potter 7 years ago
- added "watch" file; upstream tagged first release. Dmitry Smirnov 7 years ago
- ITP bug #830531 assigned Dmitry Smirnov 7 years ago
- Initial commit Dmitry Smirnov 7 years ago
- Ignore quilt dir .pc via .gitignore Dmitry Smirnov 8 years ago
- Imported Upstream version 0.0~git20160208.0.b545f2d Dmitry Smirnov 8 years ago
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