output of CODER_SETUP_SCRIPT is not logged if running headless

[johnstcn]

Motivation

If you're trying to troubleshoot issues with ENVBUILDER_SETUP_SCRIPT, you would most likely need to view the log output.

I've noticed that if running envbuilder with no stdout/stdin attached, you end up missing the log output:

Example (main@aba2f46):

$ docker run -d -e ENVBUILDER_GIT_URL=https://github.com/coder/envbuilder-starter-devcontainer -e ENVBUILDER_INIT_SCRIPT='bash' -e ENVBUILDER_SETUP_SCRIPT="echo 'setting up...'; sleep 3; echo 'done' | tee /setup.log" envbuilder:latest
envbuilder v1.0.3+dev-aba2f46 - Build development environments from repositories in a container
[...]
=== Running the setup command "echo 'setting up...'; sleep 3; echo 'done' | tee /setup.log" as the root user...
=== Running init command as user "coder": ["/bin/sh" "-c" "bash"]

Whereas running with a terminal attached results in the logs becoming visible:

docker run -it -e ENVBUILDER_GIT_URL=https://github.com/coder/envbuilder-starter-devcontainer -e ENVBUILDER_INIT_SCRIPT='bash' -e ENVBUILDER_
SETUP_SCRIPT="echo 'setting up...'; sleep 3; echo 'done' | tee /setup.log" envbuilder:latest
envbuilder v1.0.3+dev-aba2f46 - Build development environments from repositories in a container
[...]
=== Running the setup command "echo 'setting up...'; sleep 3; echo 'done' | tee /setup.log" as the root user...
setting up...
done
=== Running init command as user "coder": ["/bin/sh" "-c" "bash"]
🐳 5a1e4fa7be68 envbuilder-starter-devcontainer #  

Workaround

Redirect or tee the output to some file (as shown in the above examples).

Proposed Solution

Not sure yet!

[mafredri]

This looks like a plain logic bug, we're scanning an empty bytes.Buffer, that'll just exit immediately and never log anything.

envbuilder/envbuilder.go

Lines 895 to 900 in c4b082e

	go func() {
	scanner := bufio.NewScanner(&buf)
	for scanner.Scan() {
	opts.Logger(log.LevelInfo, "%s", scanner.Text())
	}
	}()