Marathon 101

Marathon 101

In this tutorial you’ll learn how to use Marathon via the DC/OS UI. We will launch a containerized service using a Docker image. The service outputs Hello DC/OS on standard out.

Launch A Containerized Service

We start by launching the DC/OS UI and selecting the Services view:

DC/OS UI Services view

Click on the System Marathon to open it within the DC/OS UI:

Marathon service opened in DC/OS UI

Click on the Open Service button to launch the Marathon UI:

Marathon UI launched

Click on the Create Application button to define the service and enter hello-dcos as the ID:

New App dialog in Marathon - step 1

Switch to the Docker Container tab and enter mhausenblas/hello-dcos as the image:

New App dialog in Marathon - step 2

If you now hit the Create Application button in the dialog and wait for some 10 sec you should see the following confirmation that Marathon has launched the service:

Containerized service launched

Congrats! You’ve successfully launched your first containerized service through Marathon.

View Results

Now we want to view the work our little service is carrying out. For this, close the Marathon UI by clicking Back (left upper corner) and when you’re back in the DC/OS UI, select the hello-dcos task in the Marathon service view:

Containerized service opened in DC/OS UI

Select the Log Viewer tab (right-most) in the task view and there the Output view:

Containerized service Log View in DC/OS UI

As you would expect, the Output view shows you the stdout of the service and the Error view the stderr of your task.

Scale

Since that went so well, let’s scale our containerized service: for this, launch the Marathon UI again:

Marathon UI containerized service details

Select the hello-dcos app, click on the Scale Application button and enter 5 for the number of instances:

Marathon UI containerized service Scale Application

A few seconds after you’ve you hit the Scale Application button in the dialog you should see five instances running:

Marathon UI containerized service details after scaling

Next Steps