Running Nulecules in Openshift via oc new-app


As part of the Container Tools team at Red Hat I'd like to highlight a feature of Atomic App: support for execution via OpenShift's cli command oc new-app.

The native support for launching Nulecules means that OpenShift users can easily pull from a library of Atomic Apps (Nuleculized applications) that exist in a Docker registry and launch them into OpenShift. Applications that have been packaged up in a Nulecule offer a benefit to the packager and to the deployer of the application. The packager can deliver one Nulecule to all users that supports many different platforms and the deployer gets a simplified delivery mechanism; deploying a Nulecule via Atomic App is easier than trying to manage provider definitions.


OK. Let's do a demo. I'll choose the guestbook example application developed by Kubernetes. The Nulecule defintion for this example lives here. To start the container in OpenShift via oc new-app you simply run the following command from the command line:

# oc new-app projectatomic/guestbookgo-atomicapp --grant-install-rights

This will run a pod using the container image projectatomic/guestbookgo-atomicapp. The Atomic App software that runs inside the container image will evaluate the Nulecule in the image and communicate with OpenShift in order to bring up the guestbook application, which also leverages redis.

You should now be able to see the redis and guestbook replication controllers and services:

# oc get rc
CONTROLLER     CONTAINER(S)   IMAGE(S)                  SELECTOR                REPLICAS   AGE
guestbook      guestbook      kubernetes/guestbook:v2   app=guestbook           3          3m
redis-master   redis-master   centos/redis              app=redis,role=master   1          3m
redis-slave    redis-slave    centos/redis              app=redis,role=slave    2          3m
# oc get svc
NAME           CLUSTER_IP      EXTERNAL_IP   PORT(S)    SELECTOR                AGE
guestbook                 3000/TCP   app=guestbook           3m
redis-master   <none>        6379/TCP   app=redis,role=master   3m
redis-slave    <none>        6379/TCP   app=redis,role=slave    3m

As well as the pods that are started as a result of the replication controllers:

# oc get pods
NAME                 READY     STATUS    RESTARTS   AGE
guestbook-6gujf      1/1       Running   0          3m
guestbook-m61vq      1/1       Running   0          3m
guestbook-otoz4      1/1       Running   0          3m
redis-master-wdl80   1/1       Running   0          3m
redis-slave-fbapw    1/1       Running   0          3m
redis-slave-oizwb    1/1       Running   0          3m

If you have access to the instance where the pods are running you can access it via a Node IP and NodePort, however this is not common in a hosted environment. In a hosted environment you need to expose the service in openshift via a route:

# oc expose service guestbook
route "guestbook" exposed
# oc get route guestbook
NAME        HOST/PORT                                       PATH      SERVICE     LABELS          INSECURE POLICY   TLS TERMINATION
guestbook             guestbook   app=guestbook

Now you should be able to access the guestbook service via the provided hostname; in this case it is A quick visit with Firefox gives us:


And we have a guestbook up and running!

Give oc new-app on an Atomic App a spin and give us some feeback at