Added method to get and set hostname to Hosts class

[carbonin]

Added a method for setting the host name via hostnamectl to the Hosts class.

[Fryguy]

Is all of LinuxAdmin systemctl based? If not, can we make this so that it does it properly depending on the system? @bdunne Thoughts on organizing this?

[carbonin]

So traditionally /etc/hostname and the hostname command were used to deal with this.

With systemd systems we got the new systemd-hostnamed service which seems to be adding a layer of complexity to this.

For example:
I would have expected running hostnamectl set-hostname new-host to have the same effect as echo "new-host" > /etc/hostname && hostname -F /etc/hostname, but after running the latter commands hostnamectl status still shows the old name and doesn't change until I run systemctl restart systemd-hostnamed

So I'm thinking like this:

if cmd?("hostnamectl")
  run!(cmd('hostnamectl'), :params => ['set-hostname', name])
else
  File.write("/etc/hostname", name)
  run!(cmd('hostname'), :params => ["-F", "/etc/hostname"])
end

What do you think @Fryguy ?

[Fryguy]

Yeah, that sounds good to me...We might want a higher level check for systemd instead of the individual commands, but this should work.

Also the params on the second one can be simplified to :params => {:F => "/etc/hostname"} Note, if there's a full-word version of -F, let's use that...it documents the code better and doesn't lead to googling around for what that parameter means.

[carbonin]

Yeah, it's --file so I'll use :params => {:file => "/etc/hostname"}

But on a side note:

irb(main):004:0> AwesomeSpawn::CommandLineBuilder.new.build("hostname", {:F => "/etc/hostname"})
=> "hostname --F /etc/hostname"

Am I missing something?

[kbrock]

oh noes. That is a bug. single letter

[bdunne]

We already require activesupport/core_ext so you could simplify this if there is nothing on output when unsuccessful.

run(cmd("hostname")).output.presence

[carbonin]

I'm not sure about what will be on output. It depends really on what Open3.capture3 returns here (https://github.com/ManageIQ/awesome_spawn/blob/master/lib/awesome_spawn.rb#L119) and what hostname returns in whatever failure case happened.

[bdunne]

👍 looks good, just the one comment.

[kbrock]

This is nice.

I think being explicit around success? is nice. probably overkill but... kinda like it.

👍 LGTM

[carbonin]

Do we want to add the logic to add the machine's IP address to the /etc/hosts file (https://github.com/ManageIQ/manageiq-appliance/blob/master/LINK/usr/bin/miqnet.sh#L167) here or have the caller do it in a separate call?
@Fryguy @bdunne

[kbrock]

If you are setting ip address, would you ensure that if you set a different ip address, it clears out the old ip address from /etc/hosts
If you are changing the hostname, do we also clear that out.

man, the use cases around this are complicated.

[carbonin]

I would say that the safest way to go would be to do as little as possible with each call. I don't really want to assume what people will want to do with these tools. I think it will be more clear from the calling code to do something like this https://github.com/ManageIQ/manageiq/pull/4558/files#diff-16bd2bb3c0abfe4c0381896614e7b987R238

[miq-bot]

Checked commits carbonin/linux_admin@5f550ba~...44398ae with ruby 1.9.3, rubocop 0.34.2, and haml-lint 0.13.0
2 files checked, 0 offenses detected
Everything looks good. 🍪