I love Elixir but being completely honest the ecosystem is sometimes lacking. That isn't to say that you can't do things but rather sometimes you need to rollout your own version of something. For example, Redix refused to support SSL because Redis didn't support it natively[1] even though Redis providers started wrapping Redis with SSL proxies (the maintainer has since then reconsidered and agreed to add SSL support). We also couldn't find a decent library for payload validation. There are Ecto changesets but these are things you check right before saving to a DB after you might have done a lot of work already.
Sometimes there are split clients for what I wish had a community recommended or be in the std lib. For example HTTPotion[2] vs HTTPoison[3] (names are _super_ similar and sometimes confusing).
[1] https://github.com/whatyouhide/redix/issues/77
[2] https://github.com/myfreeweb/httpotion
[3] https://github.com/edgurgel/httpoison