Do you manually install Apache from the Debian repositories? Please note that our images are completely self-contained and run independently of the rest of the software or libraries installed on your system.
You can try to deactivate the Apache installed from the repositories and the start again the services from your Discourse. To do that just execute:
sudo service apache stop
(this command will stop the Apache installed from the repo)
sudo /opt/bitnami/ctlscript.sh start
(this command will start the services of your Discourse image)
If you have any other question, please don’t hesitate to ask.