Starting with writing ejabberd modules was a real pain for me. There hasn't been much documentation around and most of the articles/blogposts are outdated. This guide should cover creating ejabberd modules from scratch with none or little experience in writing erlang. Previous experience in software development is required though.

• ejabberd installed on your local machine
• erlang installed
• git installed

Authentication modules make it possible to attach an external API or DB etc. to ejabberd in order to authenticate a user. There are various authentication modules already built-in and there's also the possibility to attach a script not written in erlang to authenticate (auth_method: external). This method is not recommended for high performance setups.

Hook-based modules allow you to interact with ejabberd based on hooks. It is for example possible to react on all message stanzas with own handlers.

You can of course also add other modules to the ejabberd runtime which e.g. add a HTTP endpoint to ejabberd.

I created a module setup which you can clone and use as a base for your own modules, just run:

$ git clone https://github.com/mweibel/ejabberd-module-bootstrap.git

And start fiddling.

Clone the bootstrap into a directory

$ git clone https://github.com/mweibel/ejabberd-module-bootstrap.git example-auth && cd example-auth

Rename src/mod_example* to src/ejabberd_auth_example*.

$ mv src/mod_example.erl src/ejabberd_auth_example.erl
$ mv src/mod_example.app.src src/ejabberd_auth_example.app.src

Edit the src/ejabberd_auth_example.app.src to contain the following code:

{application, ejabberd_auth_example,
 [
  {vsn, git},
  {description, "Ejabberd authentication example"},
  {applications, [kernel, stdlib, ejabberd]},
  {registered, []},
  {env, []}
 ]}.

Now we're going to adapt the source code to do what we want in steps. First let's create the very basic code we need to have.