Nox process manager fails to keep certain processes running

[robcole]

I'm pretty sure this must relate to exit codes and how yarn wraps different types of ongoing watch processes + how Nox traps exit codes, but haven't dug in deeply yet.

https://github.com/robcole/lucky_nox_bug has a repo that can repro this (this is just a one-off creation from @grepsedawk's https://github.com/grepsedawk/horseshoe template starter).

Steps to replicate:

1 - Clone the repo.
2 - Run script/setup.
3 - Run lucky dev

You'll note the following in the logs:

js_assets    | Done in 0.30s.
js_assets    | Done
css_assets   | Done in 0.54s.
css_assets   | Done

That alone isn't problematic, but any save events won't trigger a recompilation, as Nox seems to think the process has exited completely:

web          | [Browsersync] Proxying: http://127.0.0.1:3000
web          | [Browsersync] Access URLs:
web          |  ----------------------------
web          |  Local: http://localhost:3001
web          |  ----------------------------
web          | [Browsersync] Watching files...

... file save in app.ts happens here ...

... nothing ...

... I exit with ^C ...

^Csystem_check | Attempting to interrupt...
web          | Attempting to interrupt...
docker       | Attempting to interrupt...
docker       | Gracefully stopping... (press Ctrl+C again to force)
system_check | Done
docker       | time="2022-04-24T08:22:25-07:00" level=error msg="got 3 SIGTERM/SIGINTs, forcing shutdown"

Compare this to overmind, and you'll note that overmind will continue to properly pick up on filesystem events and recompilation will be triggered in Lucky:

web          | [Browsersync] Proxying: http://127.0.0.1:3000
web          | [Browsersync] Access URLs:
web          |  ----------------------------
web          |  Local: http://localhost:3001
web          |  ----------------------------
web          | [Browsersync] Watching files...

... file save in app.ts happens here ...

js_assets    | [watch] build started (change: "src/js/app.ts")
js_assets    | [watch] build finished
web          | [Browsersync] Reloading Browsers...

... I exit with ^C ...

^Cjs_assets    | Interrupting...
css_assets   | Interrupting...
docker       | Interrupting...
system_check | Interrupting...
web          | Interrupting...
docker       | Gracefully stopping... (press Ctrl+C again to force)
web          | Exited
css_assets   | Exited
system_check | Exited
js_assets    | Exited
[+] Running 1/1
docker       |  ⠿ Container lucky_nox_bug-postgres-1  Stopped                             0.1s
docker       | canceled
docker       | Exited

[robcole]

ps output seems helpful here as well:

# overmind

➜  lucky_nox_bug git:(main) ✗ ps aux | grep yarn
robcole           8431   4.3  0.1 35052572  79280 s003  S+    8:29AM   0:00.15 node /Users/robcole/.n/bin/yarn run browser-sync start -c bs-config.js --port 3001 -p http://127.0.0.1:3000
robcole           8435   0.0  0.0 34253900    952 s000  S+    8:29AM   0:00.00 grep --color=auto --exclude-dir=.bzr --exclude-dir=CVS --exclude-dir=.git --exclude-dir=.hg --exclude-dir=.svn --exclude-dir=.idea --exclude-dir=.tox yarn
robcole           8370   0.0  0.1 35115800  77196 s005  S+    8:29AM   0:00.18 /Users/robcole/.n/bin/node /Users/robcole/.n/bin/yarn build:css --watch
robcole           8356   0.0  0.1 34994968  80756 s004  S+    8:29AM   0:00.18 /Users/robcole/.n/bin/node /Users/robcole/.n/bin/yarn build:js --watch
robcole           8342   0.0  0.1 35361820  81072 s005  S+    8:29AM   0:00.16 node /Users/robcole/.n/bin/yarn dev:css
robcole           8341   0.0  0.1 35324956  79840 s004  S+    8:29AM   0:00.16 node /Users/robcole/.n/bin/yarn dev:js

# nox

➜  lucky_nox_bug git:(main) ✗ ps aux | grep yarn
robcole           8588   1.3  0.1 35043356  79460 s001  S+    8:30AM   0:00.15 node /Users/robcole/.n/bin/yarn run browser-sync start -c bs-config.js --port 3001 -p http://127.0.0.1:3000
robcole           8592   0.0  0.0 34253900    952 s000  S+    8:30AM   0:00.00 grep --color=auto --exclude-dir=.bzr --exclude-dir=CVS --exclude-dir=.git --exclude-dir=.hg --exclude-dir=.svn --exclude-dir=.idea --exclude-dir=.tox yarn

[grepsedawk]

For context, horseshoe is a very vanilla lucky build, but the asset builder is using esbuild --watch