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

Class DNSMembershipProvider

java.lang.Object
org.apache.catalina.tribes.membership.MembershipProviderBase
org.apache.catalina.tribes.membership.cloud.CloudMembershipProvider
org.apache.catalina.tribes.membership.cloud.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