beam-init: autostart services

[rcanderson23]

It will be expected that users will want to autostart services along with their initial service. This will attempt to start any services named 'run' in the /etc/beam-init/svc/<name>/ paths.

Related: #136

[bjorn3]

If you leave this out, beamctl list should show that it failed to start the executable without interfering with startup. That might be useful for debugging why an autostart service didn't work.

[rcanderson23]

I think this would be more confusing because we are essentially checking that run exists and is a file. I see a test failure for the expected ignore because it creates a service for a file that doesn't exist.

[rcanderson23]

Maybe an eprintln!("run not found in {path}) or something to that effect?

[bjorn3]

eprintln!() wouldn't be visible to the end user, right?

[rcanderson23]

Correct but would give cloud logs to help troubleshoot if there were a support issue.

[bjorn3]

Putting it in the beamctl list output as failed would allow self-service troubleshooting. And it would be consistent with beamctl start /non/existent. In any case, I don't think this is big enough of a deal to block this PR. I will approve this PR, though I do prefer having at least some way of debugging in place, even if just an eprintln!().

[boxofrad]

Just playing devil's advocate here 😈 but if we wanted to keep beam-init as small as possible, we could have the beam entrypoint script do something like this:

#!/usr/bin/env bash
set -euo pipefail

BASE_DIR="/etc/beam-init/svc"

for svc_dir in "$BASE_DIR"/*; do
    [[ -d "$svc_dir" ]] || continue

    svc="$(basename "$svc_dir")"

    for script in "$svc_dir"/*; do
        [[ -f "$script" ]] || continue

        echo "Starting $svc with $script"
        beamctl start --name "$svc" -- "$script"
    done
done