Overview
========
Relcool is a tool that, given a specification, assembles
releases. That is it makes an assessment of all of the Erlang/OTP Apps
available to it and the constraints that you supply as part of your
configuration and resolves a complete set of OTP Applications and
thier versions for use in the release. This may be a bit hard to
understand if you are not familiar with the way version resolutions
work in package management systems. So lets look at an example.
Lets say that you have the following OTP Applications
* app1-1.2
with dependencies::
app2
app5
app6
* app1-1.3
with dependencies::
app2
app6
* app2-2.0
with dependencies::
app6
* app2-2.1
with dependencies::
app6
app7
* app3-2.0
* app4-1.0.0
* app5-3.0
* app6-1.0
with dependencies::
app3
* app7-2.0
This is the world of OTP Apps your Relcool knows about (basically OTP
Apps in the Library Directories you have specified). You have set a
config that looks like the following::
{release, {awesome_supercool, "1.0"},
[{app1, "1.3", '>='},
{app2, "2.0", '>'},
app3]}
When the Relcool process has run you will end up with a complete release as follows::
{release, {awesome_supercool, "1.0"},
[{app1, "1.3"},
{app2, "2.1"},
{app3, "2.0"},
{app6, "1.0"},
{app7, "2.0"}]}
As you can see that is a fully realied view of your direct and
transative dependencies based on the world that Relcool knows about
and the constraints that you specified in your configuration.
