Tidewave having issue with opening TCP connection

[zacksiri]

Elixir and Erlang/OTP versions

I ran into the following issue with Tidewave + Codex

** (RuntimeError) failed to start Mix.PubSub, reason: {{:shutdown, {:failed_to_start_child, Mix.PubSub.Subscriber, {%Mix.Error{message: "failed to open a TCP socket in Mix.Sync.PubSub.subscribe/1, reason: :eperm", mix: 1}, [{Mix, :raise, 2, [file: ~c"lib/mix.ex", line: 618]}, {Mix.PubSub.Subscriber, :init, 1, [file: ~c"lib/mix/pubsub/subscriber.ex", line: 21]}, {:gen_server, :init_it, 2, [file: ~c"gen_server.erl", line: 2229]}, {:gen_server, :init_it, 6, [file: ~c"gen_server.erl", line: 2184]}, {:proc_lib, :init_p_do_apply, 3, [file: ~c"proc_lib.erl", line: 329]}]}}}, {:child, :undefined, Mix.PubSub, {Supervisor, :start_link, [[Mix.PubSub.Subscriber], [strategy: :one_for_one, name: Mix.PubSub]]}, :permanent, false, :infinity, :supervisor, [Supervisor]}}
    (mix 1.18.3) lib/mix/pubsub.ex:33: Mix.PubSub.start/0
    (mix 1.18.3) lib/mix/tasks/deps.loadpaths.ex:46: Mix.Tasks.Deps.Loadpaths.run/1
    (mix 1.18.3) lib/mix/task.ex:495: anonymous fn/3 in Mix.Task.run_task/5
    (mix 1.18.3) lib/mix/task.ex:545: Mix.Task.get_task_or_run/3
    (mix 1.18.3) lib/mix/task.ex:470: Mix.Task.maybe_load_or_compile_task/2
    (mix 1.18.3) lib/mix/task.ex:424: Mix.Task.do_run/3
    (mix 1.18.3) lib/mix/task.ex:561: Mix.Task.run_alias/6
    (mix 1.18.3) lib/mix/cli.ex:107: Mix.CLI.run_task/2

Operating system

MacOS Tahoe 26

Current behavior

1. Start Tidewave link to an app.
2. When tidewave tries to run a mix command the error comes up.

Expected behavior

There should be no errors when Tidewave tries to run a mix command.

[SteffenDE]

Minimal command to reproduce on macOS

$ sandbox-exec -p "(version 1)(allow default)(deny network*)" mix

[josevalim]

It seems Codex does not even allow us to create Unix sockets, so all Locking/PubSub features have to be effectively disabled. I will change it so it warns instead of fails.

[josevalim]

I have improved the error message here but unfortunately the only option is to disable the network sandbox when using codex. :(