Customizing ODM Liberty Configuration Using libertyHookRef

In IBM ODM, the libertyHookRef parameter appears in production configurations. This parameter is found here: ODM for production configuration parameters  This parameter allows you to inject custom configurations into the Liberty server.xml, which is especially valuable in advanced use cases.

📌 Use Case: Adding a Third Datasource

By default, ODM Helm charts support configuration of two datasources: ilogDatasource and resDatasource. But what if your JAVA SE or POJO session requires an additional (third) datasource?

This is where libertyHookRef comes into play. It allows you to extend Liberty's configuration - including additional datasources - via custom XML injected at runtime.

🛠️ How It Works

1. Create a libertyHookEnd.xml File

This XML file works similarly to datasource-dc.xml. To base your custom config on existing templates, you can inspect the contents inside a running ODM pod:

kubectl exec -it mycompany-odm-decisionserverruntime-6b77d7b696-g5mdt -- /bin/sh



cd /config/customdatasource



ls
# Output:
# datasource-dc.xml  datasource-ds.xml



cat datasource-ds.xml

2. Sample libertyHookEnd.xml

Here's an example you can adapt. Make sure to change id and jndiName to suit your requirements:

<server>



  <!-- Additional Decision Center datasource -->
  <dataSource id="dcdatasource2"
              jndiName="jdbc/ilogDataSource2"
              isolationLevel="TRANSACTION_READ_COMMITTED"
              statementCacheSize="150"
              jdbcDriverRef="postgresql-driver"
              type="javax.sql.ConnectionPoolDataSource"
              validationTimeout="0">



    <connectionManager maxPoolSize="25"
                       minPoolSize="10"
                       connectionTimeout="10s"
                       agedTimeout="30m" />



    <properties
      databaseName="mydatabase"
      user="odmAdmin"
      password="odmAdmin"
      portNumber="5432"
      tcpKeepAlive="true"
      sslMode="prefer"
      serverName="my-postgres-instance.c0cxct6erry9.us-east-2.rds.amazonaws.com" />



  </dataSource>



  <jdbcDriver id="postgresql-driver"
              javax.sql.ConnectionPoolDataSource="org.postgresql.ds.PGConnectionPoolDataSource"
              javax.sql.XADataSource="org.postgresql.xa.PGXADataSource"
              libraryRef="postgresql-library" />



  <library id="postgresql-library">
    <fileset dir="${server.config.dir}/resources" />
  </library>



</server>

3. Create a Secret

Bundle your libertyHookEnd.xml into a Kubernetes secret named customdatasource-secret:

*Create a libertyHookStart.xml file to modify the start of the server.xml and/or a libertyHookEnd.xml file to modify the end of the server.xml file.*

kubectl create secret generic customdatasource-secret \
  --from-file=libertyHookEnd.xml=./libertyHookEnd.xml

kubectl create secret generic my-liberty-config --from-file=libertyHookStart.xml --from-file=libertyHookEnd.xml

Update value.yaml

To apply the customization to Decision Center and Decision Server Runtime, add the following:

decisionCenter:
  libertyHookRef: customdatasource-secret



decisionServerRuntime:
  libertyHookRef: customdatasource-secret

Or if you're using a global customization:

customization:
  libertyHookRef: customdatasource-secret

⚠️ Important: Avoid setting libertyHookRef in multiple places. If using the customization section, remove it from individual components to prevent conflicts.

Once everything is set, apply the updated values with:

kubectl apply -f value.yaml

------------------------------
Aaron Chen
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