1.2.2 Oracle Container Runtime for Docker 18.09

This release of Oracle Container Runtime for Docker was based on the upstream Docker 18.09 release and incorporated the changes present in subsequent upstream releases since the 18.03 release.

Notably, multi-registry support is no longer in technical preview and is enabled as a feature within this release. Additionally, Oracle introduces the --default-registry option, which can be used to change the default registry to point to an alternate registry to the standard Docker Hub registry. See Section 4.6, “Setting Container Registry Options” for more information.

This release of Docker introduces an integrated SSH connection helper that allows any Docker client to connect to a remote Docker engine daemon securely over SSH. You can connect to a remote daemon using the -H ssh://user@host syntax. For example:

$ docker -H ssh://docker_user@host1.example.com run -it --rm busybox

To configure a client to use the same remote daemon always, you can set the DOCKER_HOST environment variable to contain the appropriate SSH URI. The SSH connection helper respects SSH options set for a host within the user's local SSH configuration file.

The Docker client application can now be installed as an independent package, docker-cli, so that the Docker engine daemon does not need to be installed on a system that may be used to manage a remote Docker daemon instance. The client package is automatically installed as a dependency when you install the Docker engine daemon package.

Docker 18.09 also introduces BuildKit, an overhaul of the build architecture used to build Docker images. The BuildKit mode is backward compatible with legacy build architecture, so that the Dockerfile format used to build previous images can continue to be used. BuildKit can be enabled on a system by setting the DOCKER_BUILDKIT environment variable to the value of 1. BuildKit build output is enhanced to include progress and build times and many build processes can be run in parallel to greatly enhance performance and build time. The new Docker build architecture also includes improvements to security, including options to pass secret information to builds in a more secure manner. See the upstream documentation at https://docs.docker.com/develop/develop-images/build_enhancements/ for more information. This feature is available as a technical preview in this release of Oracle Container Runtime for Docker.

Docker 18.09 uses a new version of containerd, version 1.2.0. This version of the containerd package includes many enhancements for greater compatibility with the most recent Kubernetes release.