Ansible - how to control the order of the hosts when playbook is ran

Question

Let\'s say that we have defined two machines in our inventory file:

[db-server-preprod] 172.16.0.1 172.16.0.2

If I run a playbook against this gr

Answer 1

You can use in the playbook main.yml "serial = 1" so it executes one by one, and you can ensure that the playbook would execute on the master node and after that it would execute on the others nodes.

- hosts: allnodes
  remote_user: "{{user}}"
  become: True
  serial: 1
  roles:
  - role: your_role

Answer 2

You may place your master host into separate group, then apply common role to all servers at once, then apply master-roles only to master server, and slave-roles to all servers except master using excluding pattern.

Inventory:

[all-servers]
host1
host2
host3
host4

[master-server]
host2

Playbook:

---
- hosts: all-servers
  gather_facts: no
  tasks:
    - debug: msg=role-common

- hosts: master-server
  gather_facts: no
  tasks:
    - debug: msg=role-master

- hosts: all-servers:!master-server
  gather_facts: no
  tasks:
    - debug: msg=role-slave