Import the documentation from the wiki

docs/compose/requirements.md

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+Docker compose requirements
+===========================
+
+Hardware considerations
+-----------------------
+
+You should make sure that your hardware (virtual or physical) is compatible with
+the latest Linux kernel. Also, you should have at least 2GB of total memory and
+1GB of free memory when running Mailu.
+
+Pick a distribution
+-------------------
+
+The mail server runs as a set of Docker containers. It is thus almost agnostic
+of the underlying operating system as long as a fairly recent Linux kernel is
+running and the Docker API (>= 1.11) is available.
+
+Because most of our tests run on Debian Jessie and Debian Stretch, we recommend
+one of these for the base system. Mailu should however be able to run on
+any of the [officially supported distributions](https://docs.docker.com/engine/installation/).
+
+For the purpose of this guide, all examples are based on Debian Stretch. The
+differences with other system will hardly be noticeable however.
+
+Install the distribution
+------------------------
+
+First, install Debian Stretch from the *netinstall* CD image. When installing,
+make sure that you either:
+
+ - setup a root *ext4* partition,
+ - or setup a root *btrfs* partition,
+ - or leave enough unpartitionned space for a dedicated *ext4* or *btrfs*
+   partition.
+
+If you chose to create a dedicated partition, simply mount it to
+``/var/lib/docker``. You could also create a separate partition (*ext4* is a
+sane default)  ans mount it to ``/mailu`` for storing e-mail data.
+
+Docker supports *AUFS* over *ext4* and *btrfs* as stable storage drivers.
+Other filesystems are supported such as *OverlayFS*. If you know what you are
+doing, you should go for it.
+
+Mailu uses Docker port forwarding from the host to make services
+available to external users. First, your host should have a public IP address
+configured (see ``/etc/network/interfaces``) or your router should
+forward connections to its internal IP address. Due to spam problems and
+reputation services, it
+is highly recommended that you use a dedicated IP address for your mail server
+and that you have a dedicated hostname with forward and reverse DNS entries
+for this IP address.
+
+Also, your host must not listen on ports ``25``, ``80``, ``110``, ``143``,
+``443``, ``465``, ``587``, ``993`` or ``995`` as these are used by Mailu
+services. Therefore, you should disable or uninstall any program that is
+listening on these ports (or have them listen on a different port). For
+instance, on a default Debian install:
+
+```
+apt-get autoremove --purge exim4 exim4-base
+```
+
+Finally, Docker relies heavily on ``iptables`` for port forwardings. You
+should use ``iptables-persistent`` (or any equivalent tool on other
+systems) for managing persistent rules. If you were brave enough to switch to
+``nftables``, you will have to rollback until official support is released
+by Docker or setup your own rulesets.
+
+Install Docker
+--------------
+
+Mailu relies on some of the latest Docker features. Therefore, you should
+install Docker from the official repositories instead of your distribution
+ones.
+
+The Docker website is full of [detailed instructions](https://docs.docker.com/engine/installation/)
+about setting up a proper Docker install. Default configuration should be
+suited for Mailu.
+
+Additionally, you must install ``docker-compose`` by following the instructions
+from the [Docker website](https://docs.docker.com/compose/). Compose is a
+management tool for Docker, especially suited for multiple containers systems
+like Mailu.
+
+Once everything is setup, you should be able to run the following commands
+(exact version numbers do not matter):
+
+```
+$ docker version
+Client:
+ Version:      1.11.2
+ API version:  1.23
+ Go version:   go1.6.2
+ Git commit:   b9f10c9
+ Built:        Sun Jun  5 23:17:55 2016
+ OS/Arch:      linux/amd64
+
+Server:
+ Version:      1.11.1
+ API version:  1.23
+ Go version:   go1.6.2
+ Git commit:   5604cbe
+ Built:        Mon May  2 00:06:51 2016
+ OS/Arch:      linux/amd64
+
+$ docker-compose version
+docker-compose version 1.7.1, build 6c29830
+docker-py version: 1.8.1
+CPython version: 3.5.1
+OpenSSL version: OpenSSL 1.0.2h  3 May 2016
+```
+