erlang.mk was around. My two gripes with it:

* It enforces warnings-as-errors. This is a personal preference, but I hate this while developing. I want to iterate, not have to clean up unused variables that I already know about.

* It -until very recently- failed so, so, so hard when run with parallel make. I -at first- idly wondered if -somehow- Cowboy application builds were just non-deterministic. I then remembered that I aliased 'make' to 'make -j3'. Building with 'make -j1' fixed the build and put me squarely in the Rebar camp.

Rebar is just a far better fit for how I work.

> ...did you use the cowboy_http / bootstrapped release template...

Nah.

When learning new things, if I'm not in a rush, I tend -at first- to avoid templates. I've been burned by boilerplate code in the past, and have had boilerplate code cover up the true crawling horror that was more than a couple of APIs.

I'd rather initially do things "from scratch" [0] so that I can better evaluate the thing I'm learning, and the quality of its supporting documentation, or -if the documentation is inadequate- the explanatory power of its test suite and other sample code.

I did -however- read Cowboy's Getting Started guide, along with a huge chunk of the documentation. I actually started with the API documentation, figuring that it was going to be like erlang.org's documentation. Whoops! [1]

[0] And by that, I don't mean "from first principles". I'm quite happy to read an example, partially or fully digest it, then paste it into my text editor.

[1] Again, I know how good erlang.org's documentation is and how very much work it is to make such high-quality documentation. I don't mean to slight Loïc Hoguin. :)