Installing an OpenShift Origin Cluster on Fedora 25 Atomic Host: Part 2

Cross posted with this Project Atomic Blog post

Introduction

In part 1 of this series we used the OpenShift Ansible Installer to install Openshift Origin on three servers that were running Fedora 25 Atomic Host. The three machines we'll be using have the following roles and IP address configurations:

+-------------+----------------+--------------+
|     Role    |   Public IPv4  | Private IPv4 |
+=============+================+==============+
| master,etcd | 54.175.0.44    | 10.0.173.101 |
+-------------+----------------+--------------+
|    worker   | 52.91.115.81   | 10.0.156.20  |
+-------------+----------------+--------------+
|    worker   | 54.204.208.138 | 10.0.251.101 |
+-------------+----------------+--------------+

In this blog, we'll explore the installed Origin cluster and then launch an application to see if everything works.

The Installed Origin Cluster

With the cluster up and running, we can log in as admin to the master node via the oc command. To install the oc CLI on a your machine, you can follow these instructions or, on Fedora, you can install via dnf install origin-clients. For this demo, we have the origin-clients-1.3.1-1.fc25.x86_64 rpm installed:

$ oc login --insecure-skip-tls-verify -u admin -p OriginAdmin https://54.175.0.44:8443
Login successful.

You have access to the following projects and can switch between them with 'oc project <projectname>':

  * default
    kube-system
    logging
    management-infra
    openshift
    openshift-infra

Using project "default".
Welcome! See 'oc help' to get started.

NOTE: --insecure-skip-tls-verify was added because we do not have properly signed certificates. See the docs for installing a custom signed certificate.

After we log in we can see that we are using the default namespace. Let's see what nodes exist:

$ oc get nodes
NAME           STATUS                     AGE
10.0.156.20    Ready                      9h
10.0.173.101   Ready,SchedulingDisabled   9h
10.0.251.101   Ready                      9h

The nodes represent each of the servers that are a part of the Origin cluster. The name of each node corresponds with its private IPv4 address. Also note that the 10.0.173.101 is the private IP address from the master,etcd node and that its status contains SchedulingDisabled. This is because we specified openshift_schedulable=false for this node when we did the install in part 1.

Now let's check the pods, services, and routes that are running in the default namespace:

$ oc get pods -o wide 
NAME                       READY     STATUS    RESTARTS   AGE       IP             NODE
docker-registry-3-hgwfr    1/1       Running   0          9h        10.129.0.3     10.0.156.20
registry-console-1-q48xn   1/1       Running   0          9h        10.129.0.2     10.0.156.20
router-1-nwjyj             1/1       Running   0          9h        10.0.156.20    10.0.156.20
router-1-o6n4a             1/1       Running   0          9h        10.0.251.101   10.0.251.101
$ 
$ oc get svc
NAME               CLUSTER-IP       EXTERNAL-IP   PORT(S)                   AGE
docker-registry    172.30.2.89      <none>        5000/TCP                  9h
kubernetes         172.30.0.1       <none>        443/TCP,53/UDP,53/TCP     9h
registry-console   172.30.147.190   <none>        9000/TCP                  9h
router             172.30.217.187   <none>        80/TCP,443/TCP,1936/TCP   9h
$ 
$ oc get routes
NAME               HOST/PORT                                        PATH      SERVICES           PORT               TERMINATION
docker-registry    docker-registry-default.54.204.208.138.xip.io              docker-registry    5000-tcp           passthrough
registry-console   registry-console-default.54.204.208.138.xip.io             registry-console   registry-console   passthrough

NOTE: If there are any pods that have failed to run you can try to debug with the oc status -v, and oc describe pod/<podname> commands. You can retry any failed deployments with the oc deploy <deploymentname> --retry command.

We can see that we have a pod, service, and route for both a docker-registry and a registry-console. The docker registry is where any container builds within OpenShift will be pushed and the registry console is a web frontend interface for the registry.

Notice that there are two router pods and they are running on two different nodes; the worker nodes. We can effectively send traffic to either of these nodes and it will get routed appropriately. For our install we elected to set the openshift_master_default_subdomain to 54.204.208.138.xip.io. With that setting we are only directing traffic to one of the worker nodes. Alternatively, we could have configured this as a hostname that was load balanced and/or performed round robin to either worker node.

Now that we have explored the install, let's try out logging in as admin to the openshift web console at https://54.175.0.44:8443:

image

And after we've logged in, we see the list of projects that the admin user has access to:

image

We then select the default project and can view the same applications that we looked at before using the oc command:

image

At the top, there is the registry console. Let's try out accessing the registry console by clicking the https://registry-console-default.54.204.208.138.xip.io/ link in the top right. Note that this is the link from the exposed route:

image

We can log in with the same admin/OriginAdmin credentials that we used to log in to the OpenShift web console.

image

After logging in, there are links to each project so we can see images that belong to each project, and we see recently pushed images.

And.. We're done! We have poked around the infrastructure of the installed Origin cluster a bit. We've seen registry pods, router pods, and accessed the registry web console frontend. Next we'll get fancy and throw an example application onto the platform for the user user.

Running an Application as a Normal User

Now that we've observed some of the more admin like items using the admin user's account, we'll give the normal user a spin. First, we'll log in:

$ oc login --insecure-skip-tls-verify -u user -p OriginUser https://54.175.0.44:8443                                                                                        
Login successful.

You don't have any projects. You can try to create a new project, by running

    oc new-project <projectname>

After we log in as a normal user, the CLI tools recognize pretty quickly that this user has no projects and no applications running. The CLI tools give us some helpful clues as to what we should do next: create a new project. Let's create a new project called myproject:

$ oc new-project myproject
Now using project "myproject" on server "https://54.175.0.44:8443".

You can add applications to this project with the 'new-app' command. For example, try:

    oc new-app centos/ruby-22-centos7~https://github.com/openshift/ruby-ex.git

to build a new example application in Ruby.

After creating the new project the CLI tools again give us some helpful text showing us how to get started with a new application on the platform. It is telling us to try out the ruby application with source code at github.com/openshift/ruby-ex.git and build it on top of the Source-to-Image (or S2I) image known as centos/ruby-22-centos7. Might as well give it a spin:

$ oc new-app centos/ruby-22-centos7~https://github.com/openshift/ruby-ex.git
--> Found Docker image ecd5025 (10 hours old) from Docker Hub for "centos/ruby-22-centos7"

    Ruby 2.2 
    -------- 
    Platform for building and running Ruby 2.2 applications

    Tags: builder, ruby, ruby22

    * An image stream will be created as "ruby-22-centos7:latest" that will track the source image
    * A source build using source code from https://github.com/openshift/ruby-ex.git will be created
      * The resulting image will be pushed to image stream "ruby-ex:latest"
      * Every time "ruby-22-centos7:latest" changes a new build will be triggered
    * This image will be deployed in deployment config "ruby-ex"
    * Port 8080/tcp will be load balanced by service "ruby-ex"
      * Other containers can access this service through the hostname "ruby-ex"

--> Creating resources with label app=ruby-ex ...
    imagestream "ruby-22-centos7" created
    imagestream "ruby-ex" created
    buildconfig "ruby-ex" created
    deploymentconfig "ruby-ex" created
    service "ruby-ex" created
--> Success
    Build scheduled, use 'oc logs -f bc/ruby-ex' to track its progress.
    Run 'oc status' to view your app.

Let's take a moment to digest that. A new image stream was created to track the upstream ruby-22-centos7:latest image. A ruby-ex buildconfig was created that will perform an S2I build that will bake the source code into the image from the ruby-22-centos7 image stream. The resulting image will be the source for another image stream known as ruby-ex. A deploymentconfig was created to deploy the application into pods once the build is done. Finally, a ruby-ex service was created so the application can be load balanced and discoverable.

After a short time, we check the status of the application:

$ oc status 
In project myproject on server https://54.175.0.44:8443

svc/ruby-ex - 172.30.213.94:8080
  dc/ruby-ex deploys istag/ruby-ex:latest <-
    bc/ruby-ex source builds https://github.com/openshift/ruby-ex.git on istag/ruby-22-centos7:latest 
      build #1 running for 26 seconds
    deployment #1 waiting on image or update

1 warning identified, use 'oc status -v' to see details.

NOTE: The warning referred to in the output is a warning about there being no healthcheck defined for this service. You can view the text of this warning by running oc status -v.

We can see here that there is a svc (service) that is associated with a dc (deploymentconfig) that is associated with a bc (buildconfig) that has a build that has been running for 26 seconds. The deployment is waiting for the build to finish before attempting to run.

After some more time:

$ oc status 
In project myproject on server https://54.175.0.44:8443

svc/ruby-ex - 172.30.213.94:8080
  dc/ruby-ex deploys istag/ruby-ex:latest <-
    bc/ruby-ex source builds https://github.com/openshift/ruby-ex.git on istag/ruby-22-centos7:latest 
    deployment #1 running for 6 seconds

1 warning identified, use 'oc status -v' to see details.

The build is now done and the deployment is running.

And after more time:

$ oc status 
In project myproject on server https://54.175.0.44:8443

svc/ruby-ex - 172.30.213.94:8080
  dc/ruby-ex deploys istag/ruby-ex:latest <-
    bc/ruby-ex source builds https://github.com/openshift/ruby-ex.git on istag/ruby-22-centos7:latest 
    deployment #1 deployed about a minute ago - 1 pod

1 warning identified, use 'oc status -v' to see details.

We have an app! What are the running pods in this project?:

$ oc get pods
NAME              READY     STATUS      RESTARTS   AGE
ruby-ex-1-build   0/1       Completed   0          13m
ruby-ex-1-mo3lb   1/1       Running     0          11m

The build has Completed and the ruby-ex-1-mo3lb pod is Running. The only thing we have left to do is expose the service so that it can be accessed via the router from the outside world:

$ oc expose svc/ruby-ex
route "ruby-ex" exposed
$ oc get route/ruby-ex
NAME      HOST/PORT                                 PATH      SERVICES   PORT       TERMINATION
ruby-ex   ruby-ex-myproject.54.204.208.138.xip.io             ruby-ex    8080-tcp   

With the route exposed we should now be able to access the application on ruby-ex-myproject.54.204.208.138.xip.io. Before we do that we'll log in to the openshift console as the user user and view the running pods in project myproject:

image

And pointing the browser to ruby-ex-myproject.54.204.208.138.xip.io we see:

image

Woot!

Conclusion

We have explored the basic OpenShift Origin cluster that we set up in part 1 of this two part blog series. We viewed the infrastructure docker registry and router components, as well as discussed the router components and how they are set up. We also ran through an example application that was suggested to us by the command line tools and were able to define that application, monitor its progress, and eventually access it from our web browser. Hopefully this blog gives the reader an idea or two about how they can get started with setting up and using an Origin cluster on Fedora 25 Atomic Host.

Enjoy!
Dusty

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