I found that when I exit from a SSH session on my server, the server running in Podman becomes invalid.
After searching, I found that this is because the Podman containers are started by normal users, and systemd loginctl will kill user processes when the users logout.
To check, run:
$ loginctl list-users
and I got this:
UID USER LINGER
1000 pigmoral no
1 users listed.
To fix this, we can enable the linger for the user, which will take care of the user processes when the user logs out:
$ loginctl enable-linger [USER...]
Run loginctl list-users again:
UID USER LINGER
1000 pigmoral yes
1 users listed.
You can now quit without worrying about your containers.
References: