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tutor/docs/tutorials/podman.rst
Régis Behmo b57c65440a docs: move podman install to its own tutorial
<rant>I attempted to actually run Tutor with Podman and I was sorely disappointed.
The only reliable source of docs that I found concerning the integration with
docker-compose is this blog post:
https://www.redhat.com/sysadmin/podman-docker-compose
There are no other official docs 😓

1. The instructions given in the blog post don't work out of the box. Launching
the podman service failed altogether on Ubuntu 20.04 and 20.10. It worked on
CentOS 8, but some parameters need to changed, such as the docker socket path.
2. After I got the podman service working, I managed to get an Open edX
platform running with tutor, but with the root user. Then, containers
complained that they could not write data to the bind-mounted volumes. I
attempted to run as a non-root user, and discovered that the podman socket is
only readable by root. This should explain why all commands from that blog post
are prefixed by sudo.

Long story short, I was hoping to update the tutorial. Instead, I'm just moving
it for the sake of better organisation. For the life of me, I do not understand
why some people would want to run Podman instead of Docker. Bad documentation
is an immediate turn-off for me. From my perspective, podman is mostly an
overblown marketina stunt.</rant>
2021-10-14 12:59:57 +02:00

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Running Tutor with Podman
-------------------------
You have the option of running Tutor with `Podman <https://podman.io/>`__, instead of the native Docker tools. This has some practical advantages: it does not require a running Docker daemon, and it enables you to run and build Docker images without depending on any system component running ``root``. As such, it is particularly useful for building Tutor images from CI pipelines.
The ``podman`` CLI aims to be fully compatible with the ``docker`` CLI, and ``podman-compose`` is meant to be a fully-compatible alias of ``docker-compose``. This means that you should be able to use together with Tutor, without making any changes to Tutor itself.
.. warning::
Since this was written, it was discovered that there are major compatibility issues between ``podman-compose`` and ``docker-compose``. Thus, podman cannot be considered a drop-in replacement of Docker in the context of Tutor -- at least for running Open edX locally.
.. warning::
You should not attempt to run Tutor with Podman on a system that already has native ``docker`` installed. If you want to switch to ``podman`` using the aliases described here, you should uninstall (or at least stop) the native Docker daemon first.
Enabling Podman
~~~~~~~~~~~~~~~
Podman is supported on a variety of development platforms, see the `installation instructions <https://podman.io/getting-started/installation>`_ for details.
Once you have installed Podman and its dependencies on the platform of your choice, you'll need to make sure that its ``podman`` binary, usually installed as ``/usr/bin/podman``, is aliased to ``docker``, and is included as such in your system ``$PATH``. On some CentOS and Fedora releases you can install a package named ``podman-docker`` to do this for you, but on other platforms you'll need to take of this yourself.
- If ``$HOME/bin`` is in your ``$PATH``, you can create a symbolic link there::
ln -s $(which podman) $HOME/bin/docker
- If you want to instead make ``docker`` a system-wide alias for ``podman``, you can create your symlink in ``/usr/local/bin``, an action that normally requires ``root`` privileges::
sudo ln -s $(which podman) /usr/local/bin/docker
Enabling podman-compose
~~~~~~~~~~~~~~~~~~~~~~~
``podman-compose`` is available as a package from PyPI, and can thus be installed with ``pip``. See `its README <https://github.com/containers/podman-compose/blob/devel/README.md>`_ for installation instructions. Note that if you have installed Tutor in its own virtualenv, you'll need to run ``pip install podman-compose`` in that same virtualenv.
Once installed, you'll again need to create a symbolic link that aliases ``docker-compose`` to ``podman-compose``.
- If you run Tutor and ``podman-compose`` in a virtualenv, create the symlink in that virtualenv's ``bin`` directory: activate the virtualenv, then run::
ln -s $(which podman-compose) $(dirname $(which podman-compose))/docker-compose
- If you do not, create the symlink in ``/usr/local/bin``, using ``root`` privileges::
sudo ln -s $(which podman-compose) /usr/local/bin/docker-compose
Verifying your environment
~~~~~~~~~~~~~~~~~~~~~~~~~~
Once you have configured your symbolic links as described, you should be able to run ``docker version`` and ``docker-compose --help`` and their output should agree, respectively, with ``podman version`` and ``podman-compose --help``.
After that, you should be able to use ``tutor local``, ``tutor build``, and other commands as if you had installed the native Docker tools.