Docker Engine 20.10 Released: Supports cgroups v2 and Dual Logging

Docker announced the next release of Docker Engine 20.10, adding support for cgroups v2 with improvements in the command line interface (CLI) and support for dual logging. This is the first major release after Docker Engine 19.03, released on 22nd July, 2019.

Benjamin De St Paer-Gotch, principal product manager at Docker Inc, provided details of this release in a blog post. Docker Engine comprises a client-server application, with a server dockerd, APIs specifying interfaces to be used by programs, and a CLI client, docker.

Building on the foundational Linux Kernel, Docker Engine has introduced cgroups v2 to isolate the running processes and files associated with them. Docker uses namespaces with cgroups, to achieve the said isolation. Adding this feature has enabled Docker to graduate "rootless" to a fully supported feature. Rootless mode facilitates running the entire Docker environment without root system privileges.

Supporting dual logging for the first time, various third party logging drivers can now read docker logs. This will provide a seamless approach when attempting to collect automated container log. Continuing support for CentOS8, the 20.10 release has added support for Ubuntu 20.10 and Fedora 33.

Focusing on the effectiveness of the CLI tool, Docker Engine 20.10 has new options such as:

• docker push now works similar to docker pull, so that if the image name is pushed without a tag, only the :latest tag will be pushed, rather than all tags
• Environment variables can now be stored in a file and passed when running docker exec. The new -env-file allows for parsing environment variables from the specified file
• Flags for --pull=missing|always|never options with create and run commands provide more control over when to pull the images
• Support for swarm jobs, to run batch jobs

Thanking the contributions by community, Paer-Gotch said, "When I say 'we' throughout this (blog) article I don’t just mean the (awesome) engineers at Docker, I mean the (awesome) engineers outside of Docker and the wider community that have helped shape this release."

As the year 2020 concluded, Docker has repeatedly been in the news, as they introduced subscription tiers, and Kubernetes deprecated Docker Engine support with v1.20.0.

For getting started, our readers can install the packages available via the Docker website. To learn more about this release, check out the release notes. As of this writing, Docker has released two minor versions.