Container Orchestration

In the previous chapter, we started learning concepts around containerization. We’ve learned what containers are and how they differ from Virtual Machines (VMs), as well as how to run two different types of containers (Docker and LXD). As you are now aware, containers are typically lightweight (which means you run a larger number of them than VMs on the same hardware) and are easy to manage with a command syntax that’s rather logical, such as docker run myapp to launch a container named myapp. Depending on the size of your organization, you may only need to run one or two containers to suit your needs, or perhaps you plan on scaling up to hundreds of them. While it’s rather simple to maintain a small number of containers, the footprint can quickly expand and become much harder to keep track of.

In this chapter, we’ll start looking into the concept of Container Orchestration, which can help us to better maintain the containers...

Container orchestration

In the last chapter, we covered the basics of running containers on your server. Of special note is the coverage of Docker, which will play a very important role in this chapter. We saw how to pull a Docker image as well as how to use such an image to create a container. There are many more advanced concepts we can learn when it comes to Docker, but understanding the essentials is good enough for the scope of this chapter. And now that we know how to run containers, looking further into how to more efficiently manage them is a logical next step.

Traditionally, as an administrator, you’ll ensure the critical apps and services for your organization are always healthy and available. If a critical resource stops working for any reason, it falls on you to return it to a healthy state. Regardless of whether we’re utilizing applications on a physical server, or in a VM or container, this need doesn’t change—production apps need to be...

Preparing a lab environment for Kubernetes testing

In an organization, planning a roll-out of an entire Kubernetes cluster can be fairly involved—you may have to purchase hardware and also analyze your existing environment and understand how containerization will fit in. It’s possible that some applications you want to run aren’t a good fit for containers; some don’t support running in a container at all. Assuming you’ve already checked the documentation for the applications you are wanting to run in containers and came to the conclusion that such a technology is supported, the next step is procuring the hardware (if you don’t already have a place to run it) and then setting up the cluster.

Specific to us in this book, we don’t need to contact a server vendor and submit a purchase order to simply test out the technology. If you are actually involved with the rollout of container orchestration at your organization, then it’...

Utilizing MicroK8s

If you don’t have more than one machine or enough memory on your laptop or desktop to run multiple nodes inside virtualization software such as VirtualBox, MicroK8s is a simple way to set up a Kubernetes instance for testing the platform, as well as going through the examples in this chapter. MicroK8s is actually provided by Canonical, the makers of Ubuntu. That just goes to show you how important Kubernetes is to the Ubuntu distribution, its own creator is going the extra mile to contribute to the platform. MicroK8s is available for Linux, macOS, as well as Windows. So regardless of which operating system you’re running on your laptop or desktop, you should be able to install and use it. If nothing else, it gives you a great test installation of Kubernetes that will come in handy as you learn.

To set it up, follow along with one of the subsections below that matches the operating system installed on your computer.

Installing MicroK8s on Linux...

Setting up a Kubernetes cluster

In the previous section, we set up MicroK8s, which provides us with a Kubernetes cluster on a single machine, which is great for testing purposes. That might even be all you need in order to learn Kubernetes and see how it works. If you can, I still recommend setting up a cluster manually, which will give you even more insight into how the individual components work together. That’s exactly what we’re going to do in this section.

Before we do get started, it’s important to synchronize our mindset a bit. Of all of the activities we’ve worked through so far, setting up a Kubernetes cluster manually is easily the most complex. Kubernetes itself is made up of many components, as well as settings. If any one component is incorrect or a setting is misconfigured, the entire process can fail. In this section, a great deal of care and attention was spent to ensure (as much as possible) that the process works to the point where...

Deploying containers via Kubernetes

Now it’s time to see our work pay off, and we can successfully use the cluster we’ve created. At this point, you should have either set up MicroK8s, or manually created a cluster as we’ve done in the previous section. In either case, the result is the same: we have a cluster available that we can use to deploy containers.

Keep in mind that if you’re using MicroK8s, you might need to prepend microk8s in front of kubectl commands, depending on how you set up MicroK8s. I’ll leave it up to you to add microk8s to the front of such commands as you go along, if you’re using MicroK8s and you don’t have it set up to simplify microk8s kubectl to kubectl.

Kubernetes utilizes files created in the YAML format to receive instructions. Does that sound familiar? In Chapter 15, Automating Server Configuration with Ansible, we worked with YAML files as that’s the format that Ansible playbooks are written...

Summary

In this chapter, we took containerization to the next level and implemented Kubernetes. Kubernetes provides us with orchestration for our containers, enabling us to more intelligently manage our running containers and implement services. Kubernetes itself is a very expansive topic, and there are many additional features and benefits we can explore. But for the goal of getting set up on Kubernetes and running containers with it, we did what we needed to do. I recommend that you continue studying Kubernetes and expand your knowledge, as it’s a very worthwhile subject to dig deeper into.

Speaking of subjects that are worthwhile to learn, in the next chapter, we’re going to learn how to deploy Ubuntu in the cloud! Specifically, we’ll get started with Amazon Web Services, which is a very popular cloud platform.

Relevant videos

• Setting up a Kubernetes Cluster (LearnLinuxTV): https://linux.video/setup-k8s

Further reading

• MicroK8s website: https://learnlinux.link/mk8s
• MicroK8s addons: https://learnlinux.link/mk8s-addons

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