Hey, our installer insist that $(hostname -f) resolves to an IP and the IP reverse resolves to the same name. We do need this in provisioning workflows, I recommend to get that fixed. There is an installer option to skip checks however.
Note: You need to make sure 127.0.0.1 yourhostname.com
comes first. Then you can have
127.0.0.1 localhost
the reverse order will cause the installer to break, having 2 entries seems to be fine, but needs to be in the correct order.