Added the ip_hostname option when creating a jail

[bramton]

The ip_hostname option allows the jail to resolve it's own IP address. This is very useful in cases where you run your own DNS resolver and ensures that IP addresses can be managed at a single location.

The create subcommand documentation has been modified to reflect this change. In addition, the SLAAC and DHCP options are also added.

[yaazkal]

Note that this is only going to work if there are good DNS configuration and also if the hostname has been given correctly to the jail, which is not Bastille responsibility; actually, the user should take care if using this on a jail serving DNS. Why include this as a creation option and not let the user establish it using the config command?

[bramton]

Agreed. The user has full responsibility for running a working DNS solution. I tried with the config command, which works, but is a bit more cumbersome. Here is my recipe:

bastille create bogus 14.0-RELEASE 1.2.3.4
bastille config bogus set ip_hostname true
bastille config bogus set ip4.addr

Goal of the last line is to remove the ip4 address from the config file, but the downside is that the last line boils down to ip4.addr; in the jail.conf file. A subsequent change of the ip4 address will add an additional line to the jail.conf file. E.g. after running bastille config bogus set ip4.addr 42.42.42.42, the jail.conf will look like this:

ip4.addr;
ip4.addr = 42.42.42.42;

The config file is still functional, but not very pretty. I am not sure if there is a way to prevent this, any thoughts?

[yaazkal]

OK. I don't want to close this PR since maybe anyone argues for that option at the creation time. Labeling now as "help wanted" if anyone wants to join the conversation. Let's also see what @cedwards thinks about this option. What I don't want is a plethora of issues in the future with the "sorry, it was DNS" as an answer.

That said, you are pointing that the config command maybe wants to have an unset option, which could be nice improvement. Please open a new PR with that feature if you want.

About the subsequent change of the ip.addr4, that could be a bug then, but the new unset option for the config command should prevent it in the first place.

Thanks for the feedback.