exp-leader-election

    0.4.0 • Public • Published

    Leader election for nodejs applications

    Elect a leader among several nodes using consul.

    https://www.consul.io/docs/guides/leader-election.html

    Usage

    Basic example

    Connect to consul and get notified about leadership status.

    var leaderElection = require("exp-leader-election");
    var service = require("my-little-service");
     
    var config = {
      key: "locks/my-little-service",
      consul : {
        host: "my.consul.hostname"
      }
    }
     
    leaderElection(config)
    .on("gainedLeadership", function () {
        // Whoo-hoo, we have been elected as leader! Do work.
        service.startDoingWork();
      })
    .on("error", function () {
       // Error occured, stop work.
       log.error("Leader election error occured", error);
       service.stopDoingWork();
      });

    The let-it-crash way

    If you want your application to crash in case of leader election errors, just omit the "error" listener. This is the simplest and most robust way to deal with errors, but it requires that you have a process manager (such as forever or pm2) in place to ensure that the application is restarted again.

    Configuration

    Full Example

    {
      key: "locks/my-little-service", // Only required option
      debug: console.log,
      consul: {
        host: "127.0.0.1",
        port: 8050,
        token: "asdpf2344d083udhd8723",
        ttl: 15,
        lockDelay: 10,
        readWait: 180
      }
    }

    Consul

    • consul.host: Consul hostname or ip (string)
    • consul.port: Consul port (number)
    • consul.ttl: Tuning, session ttl seconds (number, default 15)
    • consul.lockDelay: Tuning, session lock-delay seconds (number, default 10)
    • consul.readWait: Tuning, read wait seconds (number, default 180)

    To read more about the tuning parameters, see https://www.consul.io/docs/internals/sessions.html

    Debugging

    • debug: function accepting a variable number of args. Supply if you want to print debugging info.

    Install

    npm i exp-leader-election

    DownloadsWeekly Downloads

    26

    Version

    0.4.0

    License

    ISC

    Unpacked Size

    9.89 kB

    Total Files

    9

    Last publish

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