We are going to be discussing OpenShift, in particular “Hot deployments.” Hot Deployment is the process of adding new components (such as WAR files, EJB Jar files, enterprise Java beans, servlets, and JSP files, let’s see what I can teach you, and maybe help you with on your future build. Let’s turn up the heat, and read about OpenShift Hot Deploys.
What is OpenShift
OpenShift is an abstraction layer on top of Kubernetes (k8s) and provides a useful user interface that in all honesty,
k8s sometimes lacks.
For reference, look at this simple hierarchical graph to get a better grasp on what OpenShift does.
OpenShift & Hot Deploys
Testing an OpenShift
hot_deploy on Travis CI is straight forward. Let’s make sure 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.
Enable Hot Deployments on OpenShift
Open the CLI, and navigate to the directory where you want to create the application. To create a new, let’s say
MontanasHotDeployment 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:
You’ll then want to 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"
Deployment hierarchy and Travis CI
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. Here’s a simple
.travis.yml file I created to have Travis CI call OpenShift:
--- language: java provider: openshift install: skip script: echo "hot_deploy test"
It’s important to remember in OpenShift there’s a GUI that lays on top of
The image above is the OpenShift GUI, with various options you can use, and use well with Travis CI.
There you go, you just learned about OpenShift Hot Deploys! So go out there, and deploy, hot or cold – we look forward to seeing you build with us.
As always if you have any questions, any questions at all, please email me at email@example.com.