docker

Installs Docker on Ubuntu.

Well tested on 14.04. Has been known to work on 12.04.

This role started from the angstwad docker_ubuntu role and has since forked a bit, primarily to manage which version of Docker we install. Because of interdepencies between the Docker API version and software that we install (especially docker-py), we have to be careful about Docker versions.

• Our initial deploys used a fixed version of LXC Docker, pinned at 1.5.0
• Our newer deploy will still use a pinned version Docker Engine, but will be able to specify their own versions (e.g. 1.8.1)

Upgrade Support

Some Docker Engine upgrade paths have known issues. There's code in this role that attempts to resolve those issues, with minimum disruption, if those upgrade paths are encountered. The intention is to not require containers to be recreated.

This code isn't intended to catch everything; an attempt has been made to make it reasonable and non-harmful, but it hasn't been tested for all possible upgrade paths, nor with features like non-local storage drivers. With that in mind, this behavior is optional and is disabled by default.

The issues we attempt to resolve are documented in the "repair_docker_data_volumes" module.

Role Variables

• docker_version : this variable controls the version of Docker that is installed. Required. If version 1.5.0 is selected, LXC Docker will be used; otherwise the stated version of Docker Engine will be installed (if available).
• docker_attempt_upgrade_fixes : False by default. If True, the fixes described in "Upgrade Support" will be attempted
• cgroup_lite_pkg_state : When installing on an Ubuntu 13.10 host, the role will install the cgroup-lite package to provide the required cgroups support. This variable can be set to latest - the default - or to present. In the former case, the package will be updated, if necessary, when the role is run. In the latter, the package will only be added if it is not present.
• kernel_pkg_state : For 13.04+, this role will install a linux-image-extra-<version> package. This parameter works the same way as cgroup_lite_package_state, except controlling this package.

Testing

There's a directory "tests" with some Ansible playbooks that can be used for verifying role behavior. See tests/TESTS.md for more information.

License

Apache v2.0