Beginning with RHEL Atomic Host 7.2.4 release, two versions of the docker service will be included in the operating system:
docker-latest . Here are things you need to know about using these two versions of docker:
docker: docker is the default docker service that is enabled and ready to run. The service and related features are provided by the
docker RPM package.
docker-latest is also available, but is disabled by default in RHEL Atomic Host.
docker-latest is available for customers who want to try out a later version of Docker. It is provided by the
docker-latest RPM package. Only use
docker-latestif you want to try it out as a standalone service, as it is not compatible with other container tools available with Atomic Host (unless
docker-latest are the same version).
The following table describes the versions of
docker-latest included in each RHEL Atomic Host (from 7.2.4 and later):
|RHEL Atomic Host Version||
OpenShift compatibility: For information regarding compatible OpenShift component versions, please see this article.
Upgrading the docker service to docker-latest: When docker-latest offers a newer version of the Docker service, the two versions store data in different directories, use different service names and different docker executables. Because the two versions are set up separately, there are no issues related to older container images not running in the new version. To upgrade to docker-latest, you need to shut down the docker service and start the docker-latest service (as described below). This essentially starts you with a clean slate, so you have to re-pull any containers you want to run with the fresh docker-latest service.
One Docker at a time: Because both Docker services share the /run/docker directory, you cannot run both
docker-latest at the same time on the same system. For more information on new features, refer to the Docker v1.12.6 Changelog (for Docker 1.12.6).
Switching between docker and docker-latest
docker service should already be enabled and running on your Atomic Host system when it boots up. To change the Docker service to
docker-latest, you should do the following:
# systemctl stop docker # systemctl disable docker # systemctl enable docker-latest # systemctl start docker-latest
Likewise, the docker client command is set to
docker by default. To change the docker client to
docker-latest, add the following line to the end of the /etc/sysconfig/docker file:
To change the docker client back to
docker, either comment out the DOCKERBINARY line or set
Configuration files and file system layout for docker and docker-latest
The two Docker services use different configuration files and store data in different directories. For example, to add options to the docker daemon, edit /etc/sysconfig/docker for
docker or /etc/sysconfig/docker-latest for
docker-latest. Docker data are stored in /var/lib/docker for
docker and /var/lib/docker-latest for
docker-latest. See the upcoming list of configuration files, storage files, and service files to see how those files differ for these two packages.
Here is a list of useful files and directories for Docker and how the differ for
Systemd service name for starting the service:
The command you use to run, start, stop, view images, view running containers, and otherwise manage Docker-formatted images:
Directory for storing images, containers and meta data:
Add options to the Docker service:
Add networking options to Docker service:
Add storage options to Docker service:
Override default storage setup for Docker:
Default storage setup:
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