Ansible playbook to deploy to new server and remove from others

Question

I'm toying with the idea of having a playbook that runs a certain task when a server is in a group and another task when it is not in a group.

Say I have office1 with all servers and I have a primary DHCP server:

[office1]
server1
server2
server3

[dhcp]
server2

I want to make sure that I only have one DHCP server:

- include: tasks/add-dhcp.yml
  when: inventory_hostname in dhcp
- include: tasks/remove-dhcp.yml
  when: inventory_hostname not in dhcp

So that when I change DHCP to server3, it will be installed on 3 and removed from 2. The roll will then run on all office1 servers when a new DHCP deploy is done.

Any ideas with this? Is it a bad idea? How would you solve this problem?

Answer 1

If this approach works for you, then go with it. There is nothing good or bad in the way you define configuration. Other than that, you can use variables.

The conditional should however look like below:

- include_tasks: tasks/remove-dhcp.yml
  when: `dhcp` not in group_names

group_names is a magic variable which contains a list of all groups that the executing target belongs to.