Container Tools and Container Orchestration Explained

Last month, we introduced you to the concept of virtualization, and its more modern and widely used alternative, containerization. We explained what containers are and why they are so useful to data engineers and software developers. Today, we will dive into the different tools you can use to build and manage these containers and how you can handle a large number of them without having to implement everything manually.

To recap, people came up with the idea of Virtual Machines (VMs) and containers for the same purpose: to create isolated environments for simultaneously running workloads. Containers do this a bit more efficiently. Even though they are isolated, they run on the same kernel, they are more lightweight, and they boot up much faster than VMs. (If you are still not 100% clear about containers, make sure to check out our previous article here.)

Container tools

As we mentioned before, the very first container tool was Docker, and for many years, it was the standard option for building containers. However, Docker’s client-server architecture has a downside: it relies on a daemon (mostly) running as root to manage images, containers, networks, and volumes. This is basically a computer program that runs in the background without the user controlling it. Users interact with it through the CLI or REST API. While they might be necessary in some cases, daemons can crash, breaking all mechanisms which prevents you from managing the running containers.

Podman, on the other hand, is a daemonless alternative. It is open source, Linux-native, and designed to develop, manage, and run containers and pods under the OCI standards. It’s fast, lightweight, and secure, and it implements the same subcommands as Docker, facilitating migration between the two tools. The fact that there’s no daemon running with root privileges also allows for improved security.

If you recall from our previous article, OCI stands for 'Open Container Initiative', and it was created to standardize and ensure interoperability between the many different container tools.

OCI container tools do more than only create the runtime environment for containers. The OCI spec also specifies how to package applications along with their runtime environment in "OCI images." Not to mention that OCI also specifies how those images can be distributed between different machines.

Podman can create container "pods" (hence the name, which comes from “POD MANager”) that work together and organize separate containers under a common denomination to manage them as single units. This is very useful for developers because it enables them to share resources using different containers for the same application inside a pod.

Tools like Podman can help you manage your container’s lifecycle from its creation, through running, checkpointing, and restoring, to removal. They also help manage container networking and isolate the resources of containers and pods.

Container orchestration

So, you’ve built your containers. Now, you have to be able to manage them. You’ll be fine until you only have a few of them, but what happens if you have a large number of containers on your hand?

The more containers you have, the more time and resources you will need to manage each one of them manually. This is where container orchestration tools come in.

Container orchestration is the process of automating container operations throughout their entire lifecycle, including provisioning, deployment, scaling, auto-recovery, isolation, networking, etc. Without container orchestration, building highly complex programs out of multiple applications would be much more complicated and cumbersome.

By automating the management of containers, these tools make the lives of software developers and data engineers much easier. They offer a more efficient way to handle multiple containers and eliminate time-consuming tasks. But there are many more benefits they offer:

• They can scale containers to balance application workloads across infrastructure equally.
• They provide health monitoring: Containers orchestration tools automatically replace failed containers without the need for you to interfere.
• They balance workload and optimize resources throughout the infrastructure.
• They enable faster and simpler operations by automating container updates and upgrades, while ensuring service availability.?
• They offer added security: Namespaces and network policies provide isolation, preventing unauthorized access to other containers. Container orchestration also significantly reduces the chance of human error.
• They allow for lower downtime: container orchestration tools detect and fix issues like infrastructure failures much faster than we humans can.

One of the most popular tools is Kubernetes (or k8s) - an open source system for orchestrating containerized workloads and services. Originally created at Google, it was open sourced in 2015. Since then, it has gathered a vast and vibrant community of users and contributors who are continuously working on and adding new features to the platform. Other examples of container orchestration tools include Docker Swarm, Open Shift, or Nomad.

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