What

Leader election with pluggable lock-strategy backends. Only the elected leader receives exchanges — all non-leader nodes are suppressed. Headers indicate whether the current node holds the lease.

Install

npm install camel-lite-component-master

URI Syntax

master:serviceName[?backend=file&pollInterval=2000&renewInterval=5000]

| Parameter | Default | Description | |-----------------|---------|-------------| | backend | file | Lock strategy backend: file, zookeeper, or consul. | | pollInterval | 2000 | How often (ms) a non-leader polls to acquire the lock. | | renewInterval | 5000 | How often (ms) the current leader renews its lease. |

Backend Parameters

| Backend | Parameter | Default | Notes | |--------------|-------------------|----------------------|-------| | file | lockDir | os.tmpdir() | Advisory file lock via O_EXCL. Not safe on NFS shares — use zookeeper or consul in distributed deployments. | | zookeeper | hosts | localhost:2181 | Ephemeral ZooKeeper node; lock auto-released on session expiry. | | | sessionTimeout | 30000 | | | consul | host | localhost | Session + KV acquire via native fetch. | | | port | 8500 | | | | ttl | 15s | Consul session TTL string (e.g. 15s, 30s). |

Headers Set on Each Exchange

| Header | Type | Description | |-------------------------|-----------|-------------| | CamelMasterIsLeader | boolean | true if this node currently holds the lock. | | CamelMasterService | string | The service name from the URI. | | CamelMasterNodeId | string | Unique node identifier for this process. |

Usage

import { CamelContext } from 'camel-lite-core';
import { MasterComponent } from 'camel-lite-component-master';
import { TimerComponent } from 'camel-lite-component-timer';

const context = new CamelContext();
context.addComponent('master', new MasterComponent());
context.addComponent('timer', new TimerComponent());

context.addRoutes({
  configure(ctx) {
    ctx.from('master:myApp?backend=file&pollInterval=2000')
      .process(exchange => {
        if (exchange.in.getHeader('CamelMasterIsLeader')) {
          console.log('I am the leader — doing leader work');
        }
        // Non-leader nodes reach here with CamelMasterIsLeader = false
        // and an empty body; typically filter them out.
      });
  }
});

await context.start();

See Also

camel-lite — root README