rebar_vsn_rel_plugin

About

This plugin will make accurate semver compatible version strings for your Erlang OTP Releases as long as you are doing semver style versioning with tags 'v'.

Use

Add the following dep specification to the deps tuple of your rebar.config:

{rebar_vsn_rel_plugin, "",
     {git, "https://github.com/define-null/rebar_vsn_rel_plugin.git",
      {tag, "master"}}},

Then inform rebar that you want this to be used as a plugin like so:

{plugins, [rebar_vsn_rel_plugin]}.

The plugin will backup you reltool.config, check if it contans semver atom or string and change it to semver version. After release generate it will copy reltool.config back and remove the backup. If generate fails plugin will notify you on the other attempt that reltool.config was not restored and you will have to make it manually.

Explanation

This plugin is designed to take the latest semver compatible tag and turn it into a semver compatible version for the OTP Release. One of the key things it does (aside from making sure that semver is respected) is insure that there is a unique monotonically increasing version for each commit built. It does this by creating a version from both the latest tag, the epoch timestamp and the ref. The ref is actually only there to make the version human readable.

So lets say you have a repository with the tag v0.0.1 and the epoch 1348518514 on the latest commit identified by 26ff3c6 then you would end up with the version 0.0.1+build.1348518514.26ff3c6. While that version string is long, it is perfectly accurate, semver compatible, and works well with OTP. This solves many of the current versioning problems with rebar and erlang OTP Releases.

FIXME: Bug with empty git repository exists. Need to switch from os:cmd to erlang:open_port to check returning code.