Dependency management

Rebar can fetch and build projects including source code from external sources (git, hg, etc.)

It is assumed that these dependencies are available in source form and adhere to the rebar conventions. Moreover, if a project's dependencies have their own dependencies, rebar fetches and builds these transitive dependencies recursively.

Defining dependencies

Dependencies are defined in the rebar.config file by the adding the deps tuple of the following form:

{deps, [Dependency1, Dependency2, ...]}.

Each dependency is defined by a triplet {App, VsnRegex, Source} where:

• 'App' specifies the OTP application name, either as an atom or a string
• 'VsnRegex' is a string containing a regular expression that must match the OTP application version string
• 'Source' specifies the engine used to fetch the dependency along with an engine specific location:
  • {hg, Url, Rev} Fetch from mercury repository
  • {git, Url} Fetch from git repository
  • {git, Url, {branch, Branch}} Fetch from git repository
  • {git, Url, ""} == {git, Url, {branch, "HEAD"}} Fetch from git repository
  • {git, Url, {tag, Tag}} Fetch from git repository
  • {git, Url, Rev} Fetch from git repository
  • {bzr, Url, Rev} Fetch from a bazaar repository

"Raw" dependencies

A dependency specification can have an optional fourth element: [raw].

Such dependencies are called "raw" and rebar does not require them to have a standard Erlang/OTP layout which assumes the presence of either src/dependency_name.app.src or ebin/dependency_name.app files.

"Raw" dependencies can still contain rebar.config and even can have the proper OTP directory layout, but they won't be compiled.

Only a subset of rebar commands will be executed on the "raw" subdirectories: get-deps, update-deps, check-deps, list-deps and delete-deps.

Example

In rebar.config:

{deps, [
    {em, ".*", {git, "https://github.com/sheyll/erlymock.git"}},
    {nano_trace, ".*", {git, "https://github.com/sheyll/nano_trace.git", {branch, "feature/rebar-migration"}}},
    {mochiweb, "2.3.2", {git, "https://github.com/mochi/mochiweb.git", {tag, "v2.3.2"}}},
    % Or specify a revision to refer a particular commit, useful if the project has only the master branch
    % {mochiweb, "2.3.2", {git, "https://github.com/mochi/mochiweb.git", "15bc558d8222b011e2588efbd86c01d68ad73e60"},
    
    % An example of a "raw" dependency:
    {rebar, ".*", {git, "git://github.com/rebar/rebar.git", {branch, "master"}}, [raw]}
   ]}.