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Create an App from a Docker image

In this lab you will learn how to create a new project on OpenShift and how to create an application from an existing docker image.

Step 1: Add a new project from command line

Note: Please replace UserName with the username assigned to you in the commands below.

$ oc new-project mycliproject-UserName --description="My CLI Project" --display-name="CLI Project"

Upon project creation, OpenShift will automatically switch to the newly created project/namespace. If you wish to view the list of projects, run the following command:

$ oc get projects

If you have more than one project, you can switch to a different one by issuing oc project <project name>. Although you don’t want to do it now.

You can also check the status of the project by running the following command. It says that the project is currently not running anything.

$ oc status

In project CLI Project (mycliproject-UserName)

You have no services, deployment configs, or build configs.
Run 'oc new-app' to create an application.

Step 2: Create an application from a Docker Image

Next we will create an application inside the above project using an existing docker image. We will be using a very simple docker image on dockerhub that just says 'Welcome to OpenShift V3. Let us just use that for this exercise.

First create a new application using the docker image using the oc new-app command as shown below:

$ oc new-app redhatworkshops/welcome-php --name=welcome

--> Found Docker image f001b13 (8 months old) from Docker Hub for "redhatworkshops/welcome-php"

    * An image stream will be created as "welcome:latest" that will track this image
    * This image will be deployed in deployment config "welcome"
    * Port 8080/tcp will be load balanced by service "welcome"
      * Other containers can access this service through the hostname "welcome"
    * WARNING: Image "redhatworkshops/welcome-php" runs as the 'root' user which may not be permitted by your cluster administrator

--> Creating resources with label app=welcome ...
    imagestream "welcome" created
    deploymentconfig "welcome" created
    service "welcome" created
--> Success
    Run 'oc status' to view your app.

The above command uses the docker image to deploy a docker container in a pod. If you quickly run oc get pods you will notice that a deployer pod runs and it starts an application pod as shown below.

$ oc get pods

NAME               READY     STATUS    RESTARTS   AGE
welcome-1-deploy   1/1       Running   0          1m
welcome-1-dkyyq    0/1       Pending   0          0s

In the above example welcome-1-deploy is the deployer pod and the other one is the actual application pod. In a little while the deployer pod will succeed and the application pod will change for Pending to Running status.

$ oc get pods

NAME              READY     STATUS    RESTARTS   AGE
welcome-1-dkyyq   1/1       Running   0          56s

Step 3: Add a Route for your application

OpenShift also spins up a service for this application. Run the following command to view the list of services in the project (you can also use oc get svc shorthand).

$ oc get services

NAME      CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
welcome   172.30.77.93   <none>        8080/TCP   2m

You will notice the welcome service was created for this project.

However, there is no route for this application yet. So you cannot access this application from outside.

Now add a route to the service with the following command. oc expose command will allow you to expose your service to the world so that you can access it from the browser.

Note: In this example, I am using a domain name of apps.workshop.osecloud.com. Ask the instructor for the domain name suffix for your setup an change it.

$ oc expose service welcome --name=welcome

NAME      HOST/PORT                     PATH      SERVICE   LABELS
welcome   welcome.UserName.apps.workshop.osecloud.com             welcome

Step 4: Try your application

Access the application: Now access the application using curl (looking for 200 status code) or from the browser and see the result

$ oc get routes

$ curl -Is <route>
.....

Voila!! you created your first application using an existing docker
image on OpenShift.

*Step 4: Clean up*

Run the `oc get all` command to view all the components that were
created in your project.

$ oc get all

NAME TYPE SOURCE NAME TYPE STATUS POD NAME DOCKER REPO TAGS UPDATED welcome redhatworkshops/welcome-php latest 5 hours ago NAME TRIGGERS LATEST VERSION welcome ConfigChange, ImageChange 1 CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS welcome-1 welcome redhatworkshops/welcome-php:latest deployment=welcome-1,deploymentconfig=welcome 1 NAME HOST/PORT PATH SERVICE LABELS welcome welcome.apps.workshop.osecloud.com welcome NAME LABELS SELECTOR IP(S) PORT(S) welcome <none> deploymentconfig=welcome 172.30.155.37 80/TCP NAME READY REASON RESTARTS AGE welcome-1-8d7nk 1/1 Running 0 4h

Now you can delete all these components by running one command.

$ oc delete all --all

imagestream "welcome" deleted deploymentconfig "welcome" deleted route "welcome" deleted service "welcome" deleted pod "welcome-1-ynedb" deleted

You will notice that it has deleted the imagestream for the application,
the deploymentconfig, the service and the route.

You can run `oc get all` again to make sure the project is empty.

Congratulations!! You now know how to create a project, an application
using an external docker image and navigate around. Get ready for more
fun stuff!

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