If people set options in `docker_daemon_options` (e.g. `{'ipv6': false}`), the role will create the `/etc/docker/daemon.json` file and populate it with the options.
Later on, if people stop setting *all of these* options, the file used to remain in place (containing the old options) and cause trouble. This is unexpected.
If the Docker installation is managed by this role and the `/etc/docker/daemon.json` file is managed by it, it should also take care to:
- either delete the file when it's no longer necessary
- or populate it with empty options if that is what `docker_daemon_options` contains
Deleting the file instead of putting `{}` in it seems like the cleaner approach.
There's a chance that people would like to manage options in `/etc/docker/daemon.json` by themselves (without Ansible) and this new behavior when `docker_daemon_options` is empty, but this runs against having a managed Docker installation via Ansible.
This patch only deletes the `/etc/docker/daemon.json` file.
We could possibly delete the `/etc/docker` directory too, but it's more tricky to delete it only when it's empty. In some cases, the directory may contain other files and invoking the `file` module with `state: absent` will delete everything recursively, which is undesirable.
Why:
Without this modification, we can't use docker with docker_users in same
playbook than the one which install docker.
How:
Check that docker_users are set and not in docker group before include
docker-users.yml. In docker-users.yml we call reset_connection from
ansible.builtin.meta collection after docker-users are added to docker
group.
Manual success tests:
* Try to install docker with only one user in docker-users and not in
docker group => docker-users.yml include
* Try to install docker with only one user in docker-users but the user
is in docker group => docker-users.yml not include
* Try to install docker with 2 users in docker-users, one user in docker
group and the second not => docker-users.yml include
* Try to install docker with 2 users in docker-users, both are in docker
group => docker-users.yml not include
* Try to install docker with 2 users in docker-users, both are not in
docker group => docker-users.yml include
Not all package install handlers implement the `allow_downgrade` option.
For example, using Ansible >= 2.12 on Arch Linux would croak like:
Unsupported parameters for (ansible.legacy.pacman) module: allow_downgrade.
For the "package" task, add "allow_downgrade: true" to support this
scenario.
Because this option is only available starting with `ansible-core>=2.12`
for apt-based systems, we need conditional dispatching here.
