rebar3 should be searched on path

[gcb]

Elixir and Erlang/OTP versions

Erlang/OTP 27 [erts-15.2.7] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit:ns]

Elixir 1.18.3 (compiled with Erlang/OTP 27)

Operating system

linux

Current behavior

mix ignores path and defaults to MIX_REBAR3=~/.mix/something

most distros offer rebar3 in managed package, but:

$ command -v rebar3
/usr/bin/rebar3

$ mix format lib/file.ex
Could not find "rebar3", which is needed to build dependency :telemetry
Shall I install rebar3? (if running non-interactively, use "mix local.rebar --force") [Yn] n

...work around
$ MIX_REBAR3=/usr/bin/rebar3 mix format lib/file.ex
(works fine)

...alternative workaround
$ ln -s /usr/bin/rebar3 ~/.mix/rebar3
$ mix format lib/file.ex
(works fine)

Expected behavior

uses the distro rebar3, available on PATH.

[josevalim]

This is intentional. Previously, we prioritized the version on $PATH, but that lead to issues because those versions could be out of date or not fully compatible with the latest Elixir and Erlang version. Today we always install one which is tested for Erlang/Elixir pair, guaranteeing a better out of the box experience. Plus it ensures everyone on the same team is likely using the same version by default. If you want to use the PATH one, you can opt-in by setting MIX_REBAR3.

[gcb]

thanks for the history and reasoning 👍

Is there a list of all the things one should override for a predictable system? (i.e. if i don't want my ci system to download binaries all the time)

[josevalim]

Both rebar3 and the hex archive. They are downloaded with local.rebar3 and local.hex.