Every company that wants to shift to an agile software development model must consider containers as the future of app and service deployment. Containers not only dramatically simplify app deployment but also make it much easier to create portable applications that can be moved to any platform that supports the required runtime environment.
But which runtime environment are you using? For the longest time, the de facto standard container runtime environment has been Docker. But over the past year, Kubernetes has moved to deprecate the Docker runtime, so some businesses are having to shift away from Docker and use a different runtime to deploy their containers.
Which container runtimes are considered the best to replace Docker? Before we dive into that, understand that unless you have a reason for leaving Docker behind, you can easily stay with that runtime. Docker is still in active development and does a great job for container deployment.
However, there are reasons why you might need to make the switch. For example, you might have migrated your hosting operating system to one like Red Hat Enterprise Linux (RHEL), AlmaLinux, or Rocky Linux. In that case, Docker can be problematic to install.
With that in mind, let’s take a look at some of the best alternatives to Docker.
What Can Your Company Use Instead of Docker?
The first alternative you should consider is Podman. One of the main reasons for this is that Podman comes installed by default on most RHEL-based operating systems. And because Podman is a near drop-in replacement for Docker, if you already know how to use Docker, you’ll have no problem whatsoever getting up to speed with this runtime engine.
The biggest difference between Docker and Podman is that Podman doesn’t depend on a daemon. Instead, Podman launches containers as a child service, which makes Podman a daemon-less container technology.
LXD was designed specifically for LXC Linux containers and provides the required interface for connecting to the LXC library and running the daemon responsible for networking, storage, and multiple container management.
LXC is a standalone tool with a limited set of features. LXD, on the other hand, adds all of the necessary features required for modern container deployments.
The biggest difference between Docker and LXD is that LXD can run multiple processes, whereas Docker runs a single process per container. Another crucial difference is that LXD only runs on Linux, whereas Docker can run on Linux, macOS, and Windows.
Containerd is a runtime engine that manages the full lifecycle of a container. Similar to Docker, containerd uses a daemon process for the creation, starting, stopping, and destroying of containers.
Although containerd is capable of pulling images from container registries and mounting storage, it is not possible to build images or create volumes with this tool. Containerd is often considered an industry-standard runtime engine, which means you’ll find plenty of support for the technology.
RunC was designed with security in mind and usability at massive scale and is an OCI-compatible runtime. Once upon a time, runC was a module that was a part of Docker. In 2015, runC was finally released as a standalone tool and is now a widely used alternative that is standardized and interoperable. RunC also provides all of the necessary low-level functionality required by containers to interact with low-level Linux features, such as namespaces and control groups.
Is Kubernetes an Alternative to Docker?
Although both Kubernetes and Docker are capable of deploying and managing containers, they are quite different. Where Docker is a development tool for creating, sharing, and running containers, Kubernetes is a container orchestration platform for deploying and managing containers at scale.
Although that definition might sit well with some, others might point out that Docker has Docker Swarm, which makes deploying containers at scale with Docker very possible. So, yes, they can be viewed as similar technologies.
However, there is one key difference that many do not bother to mention. Where Docker is very simple to install and use, Kubernetes can be a serious challenge on every level. Kubernetes is not easy to install, nor is it easy to deploy simple applications and services.
On the other hand, Kubernetes is perfectly at home deploying very complicated full-stack applications and services at massive scale.
The better comparison would be Kubernetes and Docker Swarm because both are capable of achieving the same goal. As long as you understand that there are more moving parts and a considerably steeper learning curve with Kubernetes, you can choose either for your business. In the end, if you want ease of deployment, go with Docker, and if you want more control and features, go with Kubernetes.