testing-application.adoc

Testing Application

Now that the web application for the blog site is running and it is exposed publicly, test that the application is working and you can post new items.

With this initial deployment, a database for the site has been automatically setup using the SQLite database and a user account created. An intial set of posts has already been added.

To test that you can post additional items, you first need to log into the blog site. Click on the image top right with the silhouette of a person.

This will bring you to the login page.

Enter in the login credentials of:

Username: developer
Password: developer

When you have logged in successfully, the image top right will change to a plus symbol. This can be selected to add a new blog post.

Fill in the details for a new post and save it. Don’t add any image at this point, only text.

You should then see the post you added.

Return to the home page for the blog site by clicking on the name of the blog site in the banner. Your new post should also appear on the home page.

At this point take note of the name which appears in the banner underneath the name of the blog site. For the examples displayed in these instructions this is blog-2-6sl3c. This is the name of the Pod in which the instance of the application is currently running.

You can get a listing of all pods for running instances of the application by running:

oc get pods --selector app=blog

The --selector app=blog argument ensures that the command only lists pods which are for this application by looking for the label app=blog. This label was added automatically to all resources created for the application by the oc new-app command. It is also added to any dynamic resources such as the pods.

The oc get pods command will display output similar to:

NAME           READY     STATUS    RESTARTS   AGE
blog-2-6sl3c   1/1       Running   0          6h

The name of the pod shown should be the same as what you are seeing in the banner of the blog site. In this case we only have one instance of the application running, but if there was more than one, you would see multiple pods listed.

To demonstrate how OpenShift manages your application and ensures that it is always running, you can kill the pods for the running instances of the application. To do that you can run the command:

oc delete pod --selector app=blog

This will display output similar to:

pod "blog-2-6sl3c" deleted

Run the command:

oc get pods --selector app=blog

and you will see that although the pod was deleted, causing the instance of the application to be killed, it was replaced with a new instance, with the pod now having a new name.

NAME           READY     STATUS    RESTARTS   AGE
blog-2-8j24m   1/1       Running   0          26s

Refresh the web page for the blog site and you will see that the name of the new pod is now what is shown in the banner for the site.

What you may also have noticed is that the new post you had added to the site has gone. This is because the SQLite database which was being used was local to the container the application was running in. When the pod was killed, the container was destroyed and so any data saved had been lost.

To provide persistence for the blog posts you add, any database used will need to have an attached persistent volume into which to store data, so that it is preserved across restarts of the application and database.