While I call s3_file and use my databag_decrypt helpers, you can point to the downloads in my github repo here: https://github.com/lusis/erlang-and-centos/
The sha256 is in the filename so the checksum operator should work.
This is about as idempotent as I can get the cookbook. I've tested multiple scenarios:
- missing symlink
- missing installed product
- from scratch with neither symlink or installed product
- missing bin files
It uses erl +V to determine if the actual installed product is the one from the tarball.