Mirantis Container Runtime






What’s new

  • Added support for cgroups v2 which limits process resource usage (such as CPU, memory, and disk). MCR uses cgroups in conjunction with Linux namespaces to isolate processes inside containers. As a result, rootless is now a fully supported feature.

  • Added support for using docker logs to read container logs, regardless of the configured logging driver or plugin. Previously, docker logs did not support the use of many third party logging drivers, and this led to log data gathering issues.

    Learn more

    Refer to the Docker documentation, Configure logging drivers.

  • Added support for Ubuntu 20.04.

  • Added several CLI improvements. Along with the removal of some older and mostly unused commands, various new commands and flags have been added that make it easier to get started and to script using MCR:

    • docker push has been modified to align the default behavior with docker pull. Pushing an image name without a tag now pushes only the :latest rather than all tags, and -a/all-tags can now be used to push all the tags of an image.

    • The --pull flag has been added to the docker run and docker create commands, affording greater control over when users pull images. The option is tristate, offering missing (default), always, and late settings.

    • The -env-file flag has been added to docker exec, allowing use with a file that contains environment variables and subsequent printing or use of any of the variables inside the file.

    Learn more

    For a complete list of the CLI improvements, refer to the Docker release notes.

Deprecated features

  • Making docker pull requests against non-compliant registries that do not support pull-by-digest now results in a warning and deprecation notice (docker/cli#2872).

  • Unauthenticated TCP access now results in a more severe warning and deprecation notice (moby/moby#41285).

  • KernelMemory (docker run --kernel-memory) is deprecated (moby/moby#41254 and docker/cli#2652).

  • The aufs storage driver is deprecated (docker/cli#1484).

  • The --cluster-advertise, --cluster-store, and --cluster-store-opt flags are deprecated from the dockerd CLI (moby/moby#40614 and moby/moby#40510).

  • The legacy Dockerfile ENV name value syntax is deprecated. Use ENV name=value instead (docker/cli#2743).

  • The previously deprecated filter parameter has been removed for API v1.41 and up (moby/moby#40491).

  • The distribution manifest v2 schema 1 is now disabled on push (moby/moby#41295).

  • The MalformedHostHeaderOverride hack has been removed, causing CLI v1.12 and earlier to break. Affected users should upgrade to a more recent client version or set the DOCKER_API_VERSION environment variable to the needed API version (moby/moby#39076).

  • The docker engine subcommands have been removed (docker/cli#2207).

  • The top-level docker deploy command and .dab (“Docker Application Bundle”) file format have both been removed in favor of using docker stack deploy with compose files (docker/cli#2216).

  • The docker search --automated and docker search --stars flags have been removed in favor of using their docker search --filter equivalents (docker/cli#2338).

  • Use of reserved namespaces in engine labels is deprecated (docker/cli#2326).