rebar.config

{erl_opts, [debug_info]}.
{plugins, [rebar3_hex]}.
{deps, []}.

{cover_enabled, true}.
{eunit_opts, [verbose]}.

{pre_hooks,
  [{"(linux|darwin|solaris)", compile, "make -C c_src"},
   {"(freebsd)", compile, "gmake -C c_src"}]}.
{post_hooks,
  [{"(linux|darwin|solaris)", clean, "make -C c_src clean"},
   {"(freebsd)", clean, "gmake -C c_src clean"}]}.