I just successfully installed Discourse into a VirtualBox instance of Ubuntu 18.04 LTS Server edition. Here are the things I had to do to get it working conveniently from my host machine.
I followed these instructions for the developer advanced install.
1.The instructions seem to assume an earlier version of Ubuntu in one place.
E: Package ‘python-software-properties’ has no installation candidate
take out “python-software-properties”
sudo apt-get install software-properties-common
2. bundle install failed
To get “bundle instal” to work I needed to execute
sudo apt-get install libpq-dev
3. Getting mailcatcher to work so I could view it from the host
I had to run mailcatcher this way:
4. Being able to use SSH to get into the host
I found it convenient to SSH into the Ubuntu 18.04 guest so I could copy/paste. I used this tutorial to get it working.