Question

I have a fairly standard OTP setup with rebar and reltool. I’ve setup reltool to use a vars.config to swap in overlay template variables with {overlay_vars, "files/vars.config"}. I’ve noticed that variables other than what I have listed in vars.config also work as overlay template variables, the most obvious one of which is {{erts_vsn}}.

I assume there are other built-in variables; how do I find what they are? I’ve combed the reltool docs and come up with nothing.

Answer 1

I believe that your answer is in Rebar’s rebar_reltool module.
There, you find the definition for:

• erts_vsn
• rel_vsn
• target_dir