Can you make `mix release` return non-zero from plugin error?

I have a project released with distillery that uses a plugin.
The plugin may fail, and return :error in this case.

defmodule XxxPlugin do
  use Mix.Releases.Plugin

  def before_assembly(release = %Release{}, name: name) do
    result ="...")
    info "Return code from plugin #{result}"
    if result != 0 do
      error("Plugin failed with result #{result}")


The mix release... build is properly stopped in this case, but the status code of mix is still 0.
Is there a proper way to stop the build and return an error code ?

I tried returning :error, {:error, result}, etc…

The Distillery documentation states that Mix.Releases.Plugin callbacks like before_assembly should return an altered %Release{} struct, or nil.

The documentation is not clear on what happens when you return nil however, but I’d expect packing the release to fail (and hopefully, if Distillery provides it, using a non-zero exit status code.)

What do you mean “packing” ? Returning nil from the plugin function also results in a 0 return code.

A more proper term would be ‘building’ :slight_smile: .

As returning nil also results in a 0 return code, I think that the behaviour you want is not currently supported by Distillery. I’d suggest opening an issue on Distillery’s GitHub project.