502 Bad Gateway after upgrade to 2.7.0beta2

AI-generated summary

A user encountered a 502 Bad Gateway error after upgrading to Discourse 2.7.0beta2 via CLI. The issue occurred despite a successful rebuild, with logs showing Unicorn processes failing to start and no active processes. The user noted that a Ruby process was consuming high CPU, and the problem was resolved by changing the LXC container from unprivileged to privileged. napcok reported the issue and provided updates on the troubleshooting process.

Updated from cli:

cd /var/discourse
git pull
 ./launcher rebuild app

Everything went ok but I got 502 Bad Gateway error.

docker ps

CONTAINER ID   IMAGE                 COMMAND        CREATED          STATUS          PORTS                  NAMES
6598e9407e29   local_discourse/app   "/sbin/boot"   35 minutes ago   Up 22 minutes   0.0.0.0:2045->80/tcp   app

./launcher logs app

(105) exiting
ok: run: redis: (pid 47) 17s
ok: run: postgres: (pid 44) 17s
supervisor pid: 114 unicorn pid: 118
config/unicorn_launcher: line 71: kill: (118) - No such process
config/unicorn_launcher: line 15: kill: (118) - No such process
(114) exiting
ok: run: redis: (pid 47) 21s
ok: run: postgres: (pid 44) 21s
supervisor pid: 123 unicorn pid: 127
config/unicorn_launcher: line 71: kill: (127) - No such process
config/unicorn_launcher: line 15: kill: (127) - No such process
(123) exiting
ok: run: redis: (pid 47) 26s
ok: run: postgres: (pid 44) 26s
supervisor pid: 132 unicorn pid: 136

curl localhost:2045

<html>
<head><title>502 Bad Gateway</title></head>
<body>
<center><h1>502 Bad Gateway</h1></center>
<hr><center>nginx</center>
</body>
</html>

Discourse running inside LXC container, my second forum also inside LXC container works fine after update. Really strange.
Any advice?

Update:
I see that some ruby process is still running and eating lot of cpu:

/usr/local/bin/ruby /usr/local/bin/bundle exec config/unicorn_launcher -E production -c config/unicorn.conf.rb

Update2:
Solved by changind LXC unprivileged to privileged container.