ejabberd for Elixir Developers

improved in 21.07

Building ejabberd with Mix

You can build ejabberd with Elixir mix tool. This allows ejabberd to use Elixir libraries and ejabberd modules written in Elixir.

Please note: Elixir 1.10.3 or higher is required to build a release. Also, if using Erlang/OTP 24, then Elixir 1.11.4 or higher is required.

Make sure you have the requirements installed. On MacOS you need to use Homebrew and set up your environment.

Clone ejabberd project from Github:

git clone https://github.com/processone/ejabberd.git
cd ejabberd

Compile ejabberd:

./autogen.sh
./configure --with-rebar=mix
make

Build a development release:
```
make dev
```

There are many ways to start ejabberd, using the ejabberdctl or ejabberd scripts:

_build/prod/rel/ejabberd/bin/ejabberdctl iexlive
_build/prod/rel/ejabberd/bin/ejabberdctl live
_build/prod/rel/ejabberd/bin/ejabberd start_iex
...

You should see that ejabberd is properly started:

Erlang/OTP 23 [erts-11.1.8] [source] [64-bit] [smp:2:2] [ds:2:2:10] [async-threads:1]

2021-08-03 13:37:36.561603+02:00 [info] Loading configuration from /home/bernar/e/git/ejabberd/_build/dev/rel/ejabberd/etc/ejabberd/ejabberd.yml
2021-08-03 13:37:37.541688+02:00 [info] Configuration loaded successfully
...
2021-08-03 13:37:40.201590+02:00 [info] ejabberd 21.7.9 is started in the node ejabberd@atenea in 3.86s
2021-08-03 13:37:40.203678+02:00 [info] Start accepting TCP connections at [::]:5222 for ejabberd_c2s

Interactive Elixir (1.10.3) - press Ctrl+C to exit (type h() ENTER for help)
iex(ejabberd@localhost)1>

Now that ejabberd starts correctly, adapt to your needs the default ejabberd configuration file located at _build/dev/rel/ejabberd/etc/ejabberd/ejabberd.yml For example, enable this example Elixir ejabberd module:
```
modules:
  'ModPresenceDemo': {}
  mod_adhoc: {}
  ...
```

new in 16.02

Embedding ejabberd in an Elixir application

ejabberd is available as an Hex.pm application: ejabberd on hex.pm.

This means you can build a customized XMPP messaging platform with Elixir on top of ejabberd by leveraging ejabberd code base in your app and providing only your custom modules. This makes the management of your ejabberd plugins easier and cleaner.

To create your own application depending on ejabberd, you can go through the following steps:

Create a new Elixir app using mix:
```
mix new ejapp
cd ejapp
```

Add ejabberd package as a dependency in your mix.exs file:

defmodule Ejapp.MixProject do
...
  defp deps do
    [
     {:ejabberd, "~> 21.7"}
    ]
  end
end

Compile everything:
```
mix do deps.get, compile
```

Create paths and files for ejabberd:

mkdir config
mkdir logs
mkdir mnesia
wget -O config/ejabberd.yml https://raw.githubusercontent.com/processone/ejabberd/master/ejabberd.yml.example

Define those paths in config/config.exs:

import Config
config :ejabberd,
  file: "config/ejabberd.yml",
  log_path: 'logs/ejabberd.log'
config :mnesia,
  dir: 'mnesia/'

Start your app, ejabberd will be started as a dependency:
```
iex -S mix
```

You should see that ejabberd is properly started:

Erlang/OTP 23 [erts-11.1.8] [source] [64-bit] [smp:2:2] [ds:2:2:10] [async-threads:1]
    
Compiling 1 file (.ex)
Generated ejapp app
    
17:58:35.955 [info]  Loading configuration from config/ejabberd.yml
    
17:58:36.459 [info]  Configuration loaded successfully
...
17:58:39.897 [info]  ejabberd 21.7.0 is started in the node :nonode@nohost in 4.07s
...
17:58:39.908 [info]  Start accepting TCP connections at [::]:5222 for :ejabberd_c2s
    
Interactive Elixir (1.10.3) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>

:ejabberd_auth.try_register("test", "localhost", "passw0rd")

You are all set, you can now connect with an XMPP client !