Deploying your first application

Now that we have had a tour of the OpenShift web console to get familiar, let's use the web console to deploy our first application.

Let’s start by doing the simplest thing possible - get a plain old OCI format container image to run on OpenShift. This is incredibly simple to do. With OpenShift it can be done directly from the web console.

Before we begin, if you would like a bit more background on what a container is or why they are important click the following link to learn more: https://www.redhat.com/en/topics/containers#overview

2.1 - Deploying the container image

In this exercise, we’re going to deploy the web component of the ParksMap application which uses OpenShift's service discovery mechanism to discover any accompanying backend services deployed and shows their data on the map. Below is a visual overview of the complete ParksMap application.

Within the Developer perspective, click the +Add entry on the left hand menu.

Once on the +Add page, click Container images to open a dialog that will allow you to quickly deploy an image.

In the Image name field enter the following:

quay.io/openshiftroadshow/parksmap:latest

Leave all other fields at their defaults (but take your time to scroll down and review each one to familiarise yourself! 🎓)

Click Create to deploy the application.

OpenShift will create a Deployment that will pull this container image if it does not exist already on the cluster and create a Pod that our container will run inside. You will be taken back to the Topology view in the Developer perspective which will show the new "Parksmap" application.

2.2 - Reviewing our deployed application

If you click on the parksmap entry in the Topology view, you will see some information about that deployed application.

The Resources tab may be displayed by default. If so, click on the Details tab. On that tab, you will see that there is a single Pod that was created by your actions.

Note: A pod is the smallest deployable unit in Kubernetes and is effectively a grouping of one or more individual containers. Any containers deployed within a pod are guaranteed to run on the same machine. It is very common for pods in kubernetes to only hold a single container, although sometimes auxiliary services can be included as additional containers in a pod when we want them to run alongside our application container.

2.2 - Accessing the application

Now that we have the ParksMap application deployed. How do we access it??

This is where OpenShift Routes and Services come in.

While Services provide internal abstraction and load balancing within an OpenShift cluster, sometimes clients outside of the OpenShift cluster need to access an application. The way that external clients are able to access applications running in OpenShift is through an OpenShift Route.

You may remember that when we deployed the ParksMap application, there was a checkbox ticked to automatically create a Route. Thanks to this, all we need to do to access the application is go the Resources tab of the application details pane and click the url shown under the Routes header.

Clicking the link you should now see the ParksMap application frontend 🎉

Note: If this is the first time opening this page, the browser will ask permission to get your position. This is needed by the Frontend app to center the world map to your location, if you don’t allow it, it will just use a default location.

2.3 - Checking application logs

If we deploy an application and something isn't working the way we expect, reviewing the application logs can often be helpful. OpenShift includes built in support for reviewing application logs.

Let's try it now for our ParksMap frontend.

In the Developer perspective, open the Topology view.

Click your "Parksmap" application icon then click on the Resources tab.

From the Resources tab click View logs

2.4 - Checking application resource usage

Another essential element of supporting applications on OpenShift is understanding what resources the application is consuming, for example cpu, memory, network bandwidth and storage io.

OpenShift includes built in support for reviewing application resource usage. Let's take a look at that now.

In the Developer perspective, open the Observe view. You should see the Dashboard tab.

How much cpu and memory is your ParksMap application currently using?

You've finished exercise 2, awesome! 🎉