[CAMEL-10320] Provide a LeaderPolicy to ease the implementation of master/slave route/context

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.20.0
• Component/s: camel-core
• Labels: clustering
• Estimated Complexity: Unknown
• Assignee: Dhiraj Bokde
• Reporter: Luca Burgazzoli
• Created: 15/Sep/16 07:53
• Updated: 27/Sep/17 14:20
• Resolved: 27/Sep/17 14:20

Description

I've been working on some master/slave RoutePolicy and I'm wondering
if we can have a proper LeaderPolicy with a standardized
implementation in Camel 3.0 so one has only to notify when a
leadership is taken

In addition it may be nice to have:

• a support for Leader election from the CmelContext so the routes are
  started when the context become leader.
• an option to warm-up routes or to keep them stopped while not leader

Then we can also make it exposed in JMX so tooling are able to detect
which are current master and slaves, and whatnot.

Some possible DSL/EIP extensions:

from("...")
    .routeId("myRoute")
    .master() 
        .group("my-group")
        .consulConfiguration("http://consul-node:8500")
        .end()
    . to(...)

camelContext.setDefaultClusteredRouteConfiguration(
    ClusteredRouteConfiguration.builder()
        .withAction(ClusteredRouteAction.SUSPEND)
        .withHealtCheck(...)
        .consulConfiguration("http://consul-node:8500")
        .build()
);
  
// lookup the cluster configuration from the registry   
from("clustered:file:/data")
    .routeId("data-files")
    .to(...)

// lookup the cluster configuration from the registry  
from("master:file:/share")
    .routeId("shared-files")
    .master()
        .configuration("...")
        .end()
    .to(...)

<camelContext .../>
    <defaultMasterConfiguration/>
        <consulConfiguration url="" userName="" password=""/>
    <defaultMasterConfiguration/>

    <masterConfiguration id="master-1"/>
        <consulConfiguration url="" userName="" password=""/>
    <masterConfiguration/>

    <!-- 
        this route should pick up the default configuration 
    -->
    <route id="data-files">
        <from uri="master:file:/data"/>
        <to uri="..."/>
    <route>

   <!-- 
        this route should pick up the configuration named 
        master-1 and the master prefix should be optional.
    -->
   <route id="shared-files">
        <from uri="file:/shared"/>
        <master configurationRef="master-1"/>
        <to uri="..."/>
    <route>
</camelContext>

Issue Links

• is related to: CAMEL-10026 HealthCheck API
• is related to: CAMEL-11362 create a LeaderElectionservice
• relates to: CAMEL-11331 camel-kubernetes - Add Kubernetes based RoutePolicy
• relates to: CAMEL-10054 Create camel-atomix component
• supercedes: CAMEL-4454 Support for Cluster Singleton routes
• links to: mailing list discussion