chef_hostname Cookbook

Sets the node's hostname

• resource-driven cookbook
• supports FQDNs as hostnames
• persists after a reboot
• reloads ohai
• runs at compile-time (no need to use lazy)
• fixes up /etc/hosts so node["fqdn"] works
• runs nearly everywhere
• supports hostnamectl from systemd
• not tied to any other sysctl/etc-hosts cookbook dependecies

Motivation

• Make strong guarantees that node["fqdn"] in other recipes "just works"
• No need to lazy { node["fqdn"] }
• Be very portable

Requirements

Platforms

• Ubuntu/Debian (and derivatives like Mint/Raspbian)
• RHEL/CentOS/Scientific/Oracle/Fedora (and derivatives like Pidora)
• OpenSUSE/SLES
• FreeBSD/OpenBSD/NetBSD
• Docker Containers
• MacOSX
• Solaris
• Gentoo
• Arch
• Cisco Nexus
• Windows <-- currently a bit of a lie

Because of the way that this cookbook "Duck Types" the operating system, many systems that are not listed above have a decent chance of working out of the box provided that they implement a common pattern.

Chef

• Chef 12.5+

Cookbooks

• none

Custom Resources

hostname Sets the hostname, ensures that reboot will preserve the hostname, re-runs the ohai plugin to set the node data.

Actions

• :set: Ses the hostname

Properties

• hostname: hostname to set
• compile_time: defaults to running at compile time, set to false to disable

Chefspec / Testing

The action to be used in Chefspec/tests is "set" for exmaple:

      it 'checks if hostname is being set' do
        expect(chef_run).to set_hostname('your.hostname.com')
      end

Examples

Setting hostname to a string:

hostname "foo.example.com"

Setting hostname to the node name:

hostname node.name

Setting hostname to whatever attribute you like:

hostname node['set_fqdn']

There is no need to "lazy" arguments to templates and filenames when this is used since it forces itself to run at compile-time.

hostname node.name

# node["fqdn"] will be set here at compile time
template "/etc/motd" do
  source "motd.erb"
  variables({
    fqdn: node["fqdn"]
  })
end

# /bin/hostname will be set here at compile time
myhostname = `/bin/hostname`

file "/etc/issue" do
  content myhostname
end

The hostname resource will drop a line into /etc/hosts so that the node["fqdn"] can be resolved correctly, and will re-trigger ohai. The default is to use the node["ipaddress"]` value for the ipaddress on the /etc/hosts line. In order to override it:

hostname node["cloud"]["public_hostname"]
  ipaddress node["cloud"]["public_ipv4"]
end

In order to override the editing of the /etc/hosts file pass nil for the ipaddress (note that if you edit the /etc/hosts file you will be responsible for also reloading the ohai plugin and you will want to do both at compile-time yourself in order for node["fqdn"] to resolve)

hostname node.name
  ipaddress nil
end

Aliases can also be added to the line that hostname adds to /etc/hosts:

hostname node.name
  ipaddress "259.1.1.1"
  aliases [ "klowns.car.local", "yolo" ]
end

Notes

There are no recipes in this cookbook, the resource is meant to be used in your own custom recipes. There are no attributes in this cookbook, you can drive the resource off of whatever attribute(s) you like.

Docker container hostnames do not persist after restarts due to limitations of docker.

TODO

• fix setting node['fqdn'] correctly on windows
• aix
• xenserver (probably already supported via RHEL)
• test: exherbo, alpine, slackware, rapsbian, pidora
• smartos, omnios, openindiana, opensolaris, nexentacore?

License & Authors

Author:: Lamont Granquist ()

Copyright:: 2016-2016, Chef Software, Inc

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.