Implement -t flag from docker run (pseudo-terminal support)

[thenonameguy]

Feature Request

Certain processes check if they are running within a terminal (bound std* streams, TERM env var, etc.)
A request came up on the devenv Discord to have a similar functionality to docker-compose, which simulates TTYs by default.

Use Case:

Running tailwindcss --watch via process-compose should not exit (as the underlying esbuild process checks for a pseudo-TTY).

Proposed Change:

• Integrate a library like https://github.com/creack/pty
• Extend process-compose.yaml with tty: true|false (default: false)

Who Benefits From The Change(s)?

@jcf

Potentially could allow supplying stdin input in the TUI to interactive processes (shells).

Alternative Approaches

[F1bonacc1]

Hey @thenonameguy,

I was looking for something like this. I will give it a try.
It lacks Windows support, but I think I can work around that.

[thenonameguy]

Are you planning a similar approach? creack/pty#169
Might be worthwhile to contribute it to the pty upstream and integrate it into PC.

EDIT: some1 already wrapped it in Go: https://github.com/UserExistsError/conpty

[babariviere]

As a workaround, you can use socat like this:

processes:
  tailwind:
    command: socat - EXEC:'tailwindcss --watch',pty,setsid,ctty

It will create a fake tty for the process (in this case tailwind).

You can also use unbuffer from expect package.

processes:
  tailwind:
    command: unbuffer tailwindcss --watch

[thenonameguy]

I quite like the socat approach. Maybe we could support the https://docs.docker.com/engine/reference/commandline/compose_exec/ -T functionality with it, defaulting to false still.

So process-compose could alter the exec command if a tty: true option is set for a given process.
This could wrap the original command in a OS-specific wrapper script, that has a nice message to install socat, when it is missing in the environment.

[F1bonacc1]

Initial (no windows or STDIN) support was added in v0.88.0.
https://f1bonacc1.github.io/process-compose/configuration/#misc

I will keep it open to gather some feedback.