montana / openshift-hot-deploy

Testing a OpenShift "hot deploy" on Travis

Current OpenShift instance I have running - it's currently running Travis CI and Mongo on CentOS.

OpenShift & Hot Deploys

Testing an OpenShift hot_deploy on Travis CI. If your repository contains .openshift/markers/hot_deploy, when you perform a git push OpenShift will not rebuild the application and perform a hot deployment instead.

Apache Tomcat/Lucene

Copy changed files into the running container. This is the fast way to update a container, however the target container must support hot deploy, too so that it makes sense. Most application servers like Tomcat/Lucene supports this.

No hot deploy, okay I want a hot deploy

Alternatively you can use the following rhc in (RHEL) commands to enable and disable auto-deployment, and disable and enable hot deploys.

rhc app-configure <app> auto-deploy
rhc app-configure <app> no-auto-deploy

Hot Deploy on GCP Flowchart

Perform the following steps to enable hot deployment in OpenShift

Open the CLI, and navigate to the directory where you want to create the application. To create a new, let's say Montanas HotDeployment application, execute the following command. If you already have an OpenShift Java application, then you can work with that as well. Have a look at the following command:

rhc create-app myapp montanashotdeployment

To enable hot deployment, create a new file with the name hot_deploy inside the .openshift/markers directory. On nix machines, you can create a new file using the touch command as shown in the following command. On Windows machines, you can use file explorer to create a new file. Have a look at the following code:

touch .openshift/markers/hot_deploy 

Add the new file to the Git repository index, commit it to the local repository, and then push the changes to the application's remote Git repository:

git add .openshift/markers/hot_deploy $ git commit –am "enabled hot_deploy"

OpenShift support of hot_deploys

OpenShift supports hot deployment. Hot deployment means that you can deploy your changes without the need to restart all the application cartridges (e.g. Apache, Mongo, etc.).

The presence of the hot_deploy marker file informs OpenShift that you want to do hot deployment. Before stopping and starting the application cartridges, OpenShift checks for the existence of the hot_deploy marker file. For cartridges, hot deployment is achieved by using the deployment scanner. The scanner polls the deployments directory every 5 seconds to check for the existence of the WAR file. If the WAR file exists, it will undeploy the existing WAR file and deploy the new WAR file.

You can configure the deployment scanner's scan-interval option in .openshift/config/standalone.xml:

<subsystem xmlns="urn:jboss:domain:deployment-scanner:1.1"> <deployment-scanner path="deployments" relative-to="jboss.server.base.dir" scan-interval="5000" deployment-timeout="300" /> </subsystem>

Conclusion

It is possible to deploy the generated WAR by manually copying the file to the deploy folder of the target. If the server is running, the WAR will deploy automatically via hot deploy. Otherwise, the WAR will deploy at the next start of the server.