Automatic .appup file generation

My talk at the Erlang Factory covered several topics, but mostly people were only interested in the last 5 minutes, where I talk about how we automatically generate appup files when we are installing our software. (Makes you wonder how to do a minimum viable talk).

I created a direct (escript) interface to the automatic appup generation that doesn't require you use erlrc to manage your nodes (although, you do need erlrc installed so the escript can access the magic functions). The idea is you invoke this at the right time during whatever installation procedure you are using, and redirect the output to create the appup file (e.g., either when building a new release from an old release, or "just in time" when you are installing a new application). When things go right, it looks something like this:

% ./erlrc-makeappup erlrc 0.1.2 0.2.0 /usr/lib/erlang/lib/erlrc-0.1.2 /Users/pmineiro/tmp/usr/lib/erlang/lib/erlrc-0.2.0
{"0.2.0",
[{"0.1.2",
[{load_module,erlrc},
{load_module,erlrc_boot},
{load_module,erlrc_lib},
{load_module,erlrcdynamic},
{update,erlrcsup,supervisor},
{load_module,erlrcsupnotify},
{load_module,release_handler_1}]}],
[{"0.1.2",
[{load_module,release_handler_1},
{load_module,erlrcsupnotify},
{update,erlrcsup,supervisor},
{load_module,erlrcdynamic},
{load_module,erlrc_lib},
{load_module,erlrc_boot},
{load_module,erlrc}]}]}

That's the appup file that erlrc generates for itself when it is being upgraded from version 0.1.2 to 0.2.0. The (surprisingly simple) appup generation algorithm is outlined in the documentation.

This is available starting in version 0.2.0 of erlrc which is available on google code.