Not sure if it is relevant, but we run both a data and an app container.
No issues at all rebuilding the data container.
The error is only on the app container.
Let me know if you need more info from here.
FAILED
--------------------
Pups::ExecError: cd /var/www/discourse && su discourse -c 'bundle exec rake db:migrate' failed with return #<Process::Status: pid 3058 exit 1>
Location of failure: /pups/lib/pups/exec_command.rb:112:in `spawn'
exec failed with the params {"cd"=>"$home", "hook"=>"db_migrate", "cmd"=>["su discourse -c 'bundle exec rake db:migrate'"]}
54cb19cd99ea4d6e68a5d8c5daaecce6ee0b49593ec3b3625a458c73c67a4a0b
** FAILED TO BOOTSTRAP ** please scroll up and look for earlier error messages, there may be more than one.
./discourse-doctor may help diagnose the problem.