Creating Db2 Warehouse HADR services for a multiple cluster topology

You can create HADR services and network policies for a multiple cluster topology.

1. Generate the HADR service and network policy definitions using the create_hadr_services script on the primary database pod.
   Ports are always set up for primary and three standby databases, regardless of the your configuration.

   oc exec -it c- db2wh-primary -db2u-0 -- create_hadr_services --db-role primary --primary-name db2wh-primary --standby-name db2wh-standby --aux1-name db2wh-aux --primary-ext-host api.cluster1.ibm.com --standby-ext-host api.cluster1.ibm.com --aux1-ext-host api.cluster2.ibm.com
   
   apiVersion: v1
   kind: Service
   metadata:
     name: c-db2wh-primary-hadr-svc
   spec:
     selector:
       app: db2wh-primary
       type: engine
     ports:
       - name: db2u-hadrp
         port: 60006
         targetPort: 60006
       - name: db2u-hadrs
         port: 60007
         targetPort: 60007
       - name: db2u-hadra1
         port: 60008
         targetPort: 60008
       - name: db2u-hadra2
         port: 60009
         targetPort: 60009
     type: NodePort
   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: c-db2wh-primary-hadr-svc-ext
   spec:
     type: ExternalName
     externalName: api.cluster1.ibm.com
   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: c-db2wh-standby-hadr-svc-ext
   spec:
     type: ExternalName
     externalName: api.cluster1.ibm.com
   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: c-db2wh-aux-hadr-svc-ext
   spec:
     type: ExternalName
     externalName: api.cluster2.ibm.com
   ---
   

2. Switch to the project that the primary database is in, and use the oc apply -f command directly on the output to create the k8s services and network policies:

   oc project ${NAMESPACE_PRIMARY}
   oc exec -it c- db2wh-primary-db2u-0 -- create_hadr_services --db-role primary --primary-name db2wh-primary --standby-name db2wh-standby --aux1-name db2wh-aux --primary-ext-host api.cluster1.ibm.com --standby-ext-host api.cluster1.ibm.com --aux1-ext-host api.cluster2.ibm.com | oc apply -f -

3. Verify that the services and network policies were created:
   • One NodePort service that matches the Db2 Warehouse deployment
   • Multiple ExternalName services – one for each database in the HADR configuration

   oc get svc | grep hadr-svc

   The following will be the returned output:

   c-db2wh-aux-hadr-svc-ext       ExternalName   <none>     api.cluster2.ibm.com   <none>   9s
   c-db2wh-primary-hadr-svc        NodePort       172.30.77.20     <none>   60006:32457/TCP,60007:31243/TCP,60008:30374/TCP,60009:30977/TCP   2m15s
   c-db2wh-primary-hadr-svc-ext    ExternalName   <none>  api.cluster1.ibm.com   <none>    9s
   c-db2wh-standby-hadr-svc-ext    ExternalName   <none>     api.cluster1.ibm.com   <none>

4. Run the following command to verify that the network policy was created in the same OpenShift® Container Platform project as the Db2 Warehouse deployment:

   oc get networkpolicy | grep hadr-ext

   The following will be the returned output:

   c-db2wh-primary-hadr-ext     formation_id=db2wh-primary,type=engine         25s

5. Repeat steps 1 to 4 for each standby database, ensuring that you use the appropriate value for --db-role and that you are in the project that corresponds to the database:

   # Create services for principal standby database in cluster1
   oc project ${NAMESPACE_STANDBY}
   oc exec -it c- db2wh-standby-db2u-0 -- create_hadr_services --db-role standby --primary-name db2wh-primary --standby-name db2wh-standby --aux1-name db2wh-aux --primary-ext-host api.cluster1.ibm.com --standby-ext-host api.cluster1.ibm.com --aux1-ext-host api.cluster2.ibm.com | oc apply -f -
   
   # Check services on cluster1
   oc get svc | grep hadr-svc
   # Output:
   c-db2wh-aux-hadr-svc-ext       ExternalName   <none>           api.cluster2.ibm.com   <none>                                                                            9s
   c-db2wh-primary-hadr-svc        NodePort       172.30.77.20     <none>                            60006:32457/TCP,60007:31243/TCP,60008:30374/TCP,60009:30977/TCP                   2m15s
   c-db2wh-primary-hadr-svc-ext    ExternalName   <none>           api.cluster1.ibm.com   <none>                                                                            9s
   c-db2wh-standby-hadr-svc        NodePort       172.30.247.77     <none>                            60006:32649/TCP,60007:31384/TCP,60008:30473/TCP,60009:30652/TCP                   1m10s
   c-db2wh-standby-hadr-svc-ext    ExternalName   <none>           api.cluster1.ibm.com   <none>     
   
   # Create services for auxiliary standby database in cluster2
   oc project ${NAMESPACE_AUX}
   oc exec -it c- db2wh-aux-db2u-0 -- create_hadr_services --db-role aux1 --primary-name db2wh-primary --standby-name db2wh-standby --aux1-name db2wh-aux --primary-ext-host api.cluster1.ibm.com --standby-ext-host api.cluster1.ibm.com --aux1-ext-host api.cluster2.ibm.com | oc apply -f –
   
   # Check services on cluster2
   oc get svc | grep hadr-svc
   # Output:
   c-db2wh-aux-hadr-svc        NodePort       172.30.241.25     <none>                            60006:34578/TCP,60007:31546/TCP,60008:30698/TCP,60009:30448/TCP                   10s
   c-db2wh-aux-hadr-svc-ext       ExternalName   <none>           api.cluster2.ibm.com   <none>                                                                            9s
   c-db2wh-primary-hadr-svc-ext    ExternalName   <none>           api.cluster1.ibm.com   <none>                                                                            9s
   c-db2wh-standby-hadr-svc-ext    ExternalName   <none>           api.cluster1.ibm.com   <none>     
   

   The example shows one NodePort service that corresponds to each database in the OpenShift cluster, for example primary plus standby in Cluster1 and aux in Cluster2, but one ExternalName service that corresponds to each database in the topology, for example primary plus standby plus aux in Cluster1 and the same in Cluster2.