This commit adds the overlayfs type to the lxc_container module. In
Adding the overlayfs type the commit adds the ability to clone a
container. While cloning is not locked down to only the overlayfs
container backend it is of particular interest when using the overlayfs
backend as it provides for amazingly fast snapshots.
Changes to the resource types and documentation have been added on how
the new backend type can be used along with the clone operation.
This PR addresses a question asked on the original merged pull request
for overlayfs support which came from @fghaas on PR
"https://github.com/ansible/ansible-modules-extras/pull/123".
The overlayfs archive function is a first class function and will
allow for the containers to be backed-up using all methods which
brings support up to that of all other storage backends.
The HipChat module declares to support check_mode,
but the message is sent in any case.
With this, if executed in check mode, the module will exit
before actually sending the message to HipChat.
It will return changed=False, as per the convention
for notifications modules.
The documentation for the `state` field is not very clear.
It says possible values are "installed, uninstalled" and default value is "present"
The examples below alow uses `present` and `absent`.
This patch uses "absent" and "present" instead of "installed" and "uninstalled"
Moreover, this is consistent with other packaging modules, like homebrew itself