I’m running this blog (and couple other blogs and side-projects) on DigitalOcean since 2014. Till this week, my VM looked like a typical VM from 90’: mysql server, nginx+php, irssi. Nothing special about that setup really. But, since I’m currently busy working on the OpenShift v3 platform, I convinced myself to upgrade to the “containers era”.

This blog post describes the steps I’ve take to run the latest OpenShift v3 platform and next post will explain how I containerized the apps I ran (this site included).

The first thing I’ve to get familiar myself was this repository that contains the OpenShift Ansible installer.

Since I love to automatize things and I don’t have that much free time to configure everything myself, I really fall in love with this installation system. It does not require anything special on the VM, except password-less SSH authentication. And because DigitalOcean already have my SSH key, that is no-op.

The next step was to actually create a VM that I will host my OpenShift v3. I choosed the 2GB/2CPU one, which is a little bit more expensive (~$20/month), but it gives me a little bit more space for running containers. It also comes with 40GB of SSD storage, which is perfectly fine for some simple apps and I can use the SSD as a swap if I really need to.

So the VM is up and running. I gave it name alpha.mifo.sk. The reason is that for now, I’m going with all-in-one installation, but in future, who knows… I selected the CentOS 7.1 box, which should be perfectly file and supported by the Ansible installer and the OpenShift v3 itself. The only change I dit to that VM was to fix the /etc/hosts file: alpha.mifo.sk

For some reason, the DNS name is assigned to point to, which might cause troubles with Ansible.

Now it is time to create the Ansible inventory file. I created mine ./alpha/hosts file with the following content:


openshift_node_kubelet_args={'max-pods': ['40'], 'image-gc-high-threshold': ['90'], 'image-gc-low-threshold': ['80']}

alpha.mifo.sk openshift_ip= openshift_hostname=alpha.mifo.sk openshift_public_ip= openshift_public_hostname=alpha.mifo.sk

alpha.mifo.sk openshift_ip= openshift_hostname=alpha.mifo.sk openshift_public_ip= openshift_public_hostname=alpha.mifo.sk

alpha.mifo.sk openshift_ip= openshift_hostname=alpha.mifo.sk openshift_public_ip= openshift_public_hostname=alpha.mifo.sk

This configuration basically says:

  • I want all-in-one VM that runs the “master” but also acts as a “node” in the OpenShift cluster.
  • I want the etcd to run on the same VM as well.
  • The node should have limit for maximum pods set to 40 (just a pre-caution…)

Now it is time to clone the Ansible installer GIT repository:

$ git clone https://github.com/openshift/openshift-ansible

And finally proceed with the installation:

$ cd openshift-ansible
$ ansible-playbook playbooks/byo/config.yml --inventory ~/alpha/hosts

You can now watch the Ansible installation output (should take less than ~5 minutes). After it finishes, the OpenShift Console should be available at https://alpha.mifo.sk:8443 (replace with your hostname…).

After you login to the console, you will notice that it is not really the securest place in the world. OpenShift basically allows any user to login and it will automatically create new users. Not cool for “production” use.

Fortunatelly, OpenShift offers pretty long list of supported identity providers. , so I choosed the Github one, which is really easy to configure.

After I configured it and restarted the origin-master systemd service, I noticed another odd thing. Now when I’m going to OpenShift login page, I’m redirected to Github application page for authentication. After I allow my Github app to use my own Github account informations, I get redirected back to OpenShift console and I’m logged in.

So what is odd here? Any Github user can now login to my OpenShift console! To fix this, you have to set the mappingMethod property in configuration to “lookup” (and restart openshift server).

By doing that, only users that logged in already will have access to OpenShift console, which is fine for me. If I want to give access to another user, I can just manually create it in OpenShift, or temporarely open logging by switching to “claim”.

Another post-installation step, that I did for my OpenShift installation was to configure NFS server. Why? Because I want to be able to use the persistent volumes in my containers (like database…). You can read how to setup persistent storage in OpenShift in the official documentation

The last thing I noticed after installation, was that the “node” was in “un-schedulable” state. That means, no container are allowed to schedule on this VM. To fix that, you have to run:

$ oadm manage-node alpha.mifo.sk --schedulable=true

Now the containers will start to launch and you are good to go create your applications and deploy some services.

Next time, I will explain how I containerized this blog and deployed it in OpenShift.