Comparing common docker and cri commands

 

Comparing docker and crictl command line options

Docker and CRI (Container Runtime Interface) are two popular ways to manage and run containers on a Linux system. Both technologies offer a set of commands and tools for working with containers, but there are some key differences between the two. In this blog post, we will compare some common Docker and CRI commands to help you understand the similarities and differences between the two technologies.

First, let's take a look at the docker run command. The docker run command is used to start a new container from an image. The command takes a number of options, such as the image name, ports to expose, and environment variables to set. The docker run command also allows you to specify a command to run inside the container, which is useful for running a specific application or service.

In contrast, the equivalent command in CRI is the crictl run command. The crictl run command also starts a new container from an image, but it takes a different set of options and arguments. For example, instead of specifying ports to expose, you would specify the container's network namespace. Additionally, crictl run command also takes an additional option --runtime which allows you to specify the runtime to use (e.g. containerd).

Another common command is the docker ps command, which is used to list all running containers. The docker ps command lists information about each container, including the container ID, image name, status, and ports that are exposed.

The equivalent command in CRI is the crictl ps command. Like the docker ps command, crictl ps also lists all running containers and displays information about each container. However, the crictl ps command takes a different set of options and arguments, and the output format may also be different.

Both docker stop and crictl stop commands are used to stop a running container. Similarly, both docker rm and crictl rm commands are used to remove a container.

Another common command is the docker logs command, which is used to view the logs of a running container. The equivalent command in CRI is crictl logs command. Both commands take the same options, such as the container ID or name, and display the logs in the same format.

In addition to these commands, both Docker and CRI also provide other tools and features for managing and working with containers. For example, Docker provides the Docker Engine, which is the underlying technology that runs containers on a host. CRI, on the other hand, provides a set of APIs and libraries that allow different container runtimes (e.g. containerd, cri-o) to integrate with Kubernetes, which is a popular container orchestration system.

One of the main differences between Docker and CRI is that Docker is a complete container platform that includes both the runtime and the management tools, while CRI is focused on providing a consistent interface for different container runtimes to integrate with Kubernetes. This means that if you're using Kubernetes, you'll likely be using CRI and a container runtime like containerd, rather than Docker directly.

In conclusion, both Docker and CRI are powerful tools for managing and running containers on a Linux system. While there are some similarities between the two technologies, there are also some key differences, particularly in terms of the commands and tools that are available. Understanding these differences can help you make the best choice for your specific use case and environment.