Create our own Run Engine commands

If the predefined Run Engine commands do not satisfy your requirements, we can create our own commands.

Note: Using Run Engine commands is one approach by which IBM uses to implement environment configurations. Based on your scenario, we can implement a custom solution to modify environment parameters and container configurations that might better suit your needs.

Task info

We can define commands by using two main approaches:

• To use Java or Groovy classes to change configurations, we can define your class to inherit from the BaseCommand class (in Docker_container/SETUP/lib/engine-command.jar).

• To use other scripting languages, such as Python, we can define your class to inherit from ScriptCommand.

Procedure

1. Create an empty Java or Groovy project and create three child directories (src, META-INF, script).

   • project

     • src

     • META-INF

     • scripts

2. Add engine-command.jar as a dependency.

3. Create a class that inherits from BaseCommand or ScriptCommand. Within the class, create a runCmd method to define your actions.

   • Extend the BaseCommand to implement logic by using Java or Groovy code.

   • Extend the ScriptCommand to implement logic by using other scripting languages such as Python.

   For example, the following class WCCommand inherits from the ScriptCommand and the command outputs a string

   class WCCommand extends ScriptCommand{
   void runCmd(String[] args) {
       println "wc-sample"
   }
   }

4. Save the class in the src directory.

5. If needed, create scripts in the script directory to complete a configuration. For example, the following Python script (createJMSQueue.py) uses WebSphere Application Server wsadmin scripting commands to configure IBM MQ JMS resources.

   queueName = sys.argv[1]
   queueManager = sys.argv[2]
   AdminTask.createWMQQueue('server1(cells/localhost/nodes/localhost/servers/server1|server.xml)', '[-name '+ jndiName +' -jndiName '+jndiName+' -queueName '+ queueName + ' -qmgr '+queueManager+' -description JMSQueue ]') 
   print ("Create JMS queues successfully!")  
   AdminConfig.save()

   • For more information about wsadmin commands for IBM MQ, see Configure JMS resources using wsadmin scripting commands.

   • For general information about wsadmin commands, see Scripting the application serving environment

6. Create a .properties file and save to the META-INF directory. Name the file as the Run Engine command name to use. For example, to use a Run Engine command such as

   run create-jms-queues

   Then create a properties file named create-jms-queues.properties.

7. In the properties file, specify a main.class name-value pair to specify the class createdd. Also specify a main.script name-value pair if you created a script in step 5. For example,

   main.class=com.ibm.commerce.engine.cmd.twas.WasCommand
   main.script=createJMSQueue.py

8. Build and package the /src and /META-INF directories into a jar file.

9. Create or update a Dockerfile to include and use our custom Run Engine command. For more information about creating Dockerfiles, see Building and deploying new Docker images

   • Ensure that you copy your jar file to the /SETUP/lib path in the Docker container.

   • Ensure that you copy your scripts to the /SETUP/scripts path in the Docker container.

   For example,

   FROM <dockerhost>/commerce/ts-app:latest
   COPY new.jar /SETUP/lib
   COPY scripts/ /SETUP/scripts
   RUN  run create-jms-queues inbound mq FVT