Package org.apache.catalina.tribes.membership.cloud

Class DNSMembershipProvider

  • All Implemented Interfaces:
    ChannelListener, Heartbeat, MembershipProvider
    public class DNSMembershipProvider
extends CloudMembershipProvider
    A MembershipProvider that uses DNS to retrieve the members of a cluster.

    Configuration example for Kubernetes

    server.xml 
     
 <Server ...

   <Service ...

     <Engine ...

       <Host ...

         <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster">
           <Channel className="org.apache.catalina.tribes.group.GroupChannel">
             <Membership className="org.apache.catalina.tribes.membership.cloud.CloudMembershipService"
                 membershipProviderClassName="org.apache.catalina.tribes.membership.cloud.DNSMembershipProvider"/>
           </Channel>
         </Cluster>
         ...
    minimal example for the Service my-tomcat-app-membership, note the selector
    dns-membership-service.yml 
     
 apiVersion: v1
 kind: Service
 metadata:
   annotations:
     service.alpha.kubernetes.io/tolerate-unready-endpoints: "true"
     description: "The service for tomcat cluster membership."
   name: my-tomcat-app-membership
 spec:
   clusterIP: None
   selector:
     app: my-tomcat-app
    First Tomcat pod minimal example, note the labels that must correspond to the selector in the service.
    tomcat1.yml 
     
 apiVersion: v1
 kind: Pod
 metadata:
   name: tomcat1
   labels:
     app: my-tomcat-app
 spec:
   containers:
   - name: tomcat
     image: tomcat
     ports:
     - containerPort: 8080
    Environment variable configuration
    DNS_MEMBERSHIP_SERVICE_NAME=my-tomcat-app-membership

    • Constructor Detail

      • DNSMembershipProvider

        public DNSMembershipProvider()

    • Method Detail

      • start

        public void start​(int level)
           throws java.lang.Exception
        Description copied from interface: MembershipProvider
        Start the membership provider.
        Specified by:
        start in interface MembershipProvider
        Overrides:
        start in class CloudMembershipProvider
        Parameters:
        level - the readiness level
        • Channel.DEFAULT - will start all services
        • Channel.MBR_RX_SEQ - starts the membership receiver
        • Channel.MBR_TX_SEQ - starts the membership broadcaster
        Throws:
        java.lang.Exception - if an error occurs

      • stop

        public boolean stop​(int level)
             throws java.lang.Exception
        Description copied from interface: MembershipProvider
        Stop the membership provider.
        Specified by:
        stop in interface MembershipProvider
        Overrides:
        stop in class CloudMembershipProvider
        Parameters:
        level - the readiness level
        • Channel.DEFAULT - will stop all services
        • Channel.MBR_RX_SEQ - stops the membership receiver
        • Channel.MBR_TX_SEQ - stops the membership broadcaster
        Returns:
        true if successful
        Throws:
        java.lang.Exception - if an error occurs

      • accept

        public boolean accept​(java.io.Serializable msg,
                      Member sender)
        Description copied from interface: ChannelListener
        Invoked by the channel to determine if the listener will process this message or not.
        Specified by:
        accept in interface ChannelListener
        Overrides:
        accept in class CloudMembershipProvider
        Parameters:
        msg - Serializable
        sender - Member
        Returns:
        boolean