Is it possible to have pair of IPs in Ansible?

Question

I have so many HA machines that one of them is primary and the other is standby. I have this playbook that copies a config file from primary and then from standby on local machine then use those files as input for a python script:

- hosts: primary
  remote_user: root
  tasks:
  - name: copy the config of primary to local
    fetch:
      src: /data1/cronjobs/gen_ddl
      dest: /AnsibleDir/primary
      flat: yes
- hosts: standby
  remote_user: root
  tasks:
  - name: copy the config of standby to local
    fetch:
      src: /data1/cronjobs/gen_ddl
      dest: /AnsibleDir/standby
      flat: yes
- hosts: 127.0.0.1
  connection: local
  remote_user: root
  tasks:
  - name: run python script
    shell: /AnsibleDir/driver.py
    register: myshell_output
  - name: copy the output to a local file
    copy:
      content: "{{ myshell_output.stdout }}"
      dest: "/AnsibleDir/output.{{ host }}"  

and I use this command:
ansible-playbook -i /Ansible/hostfile /Ansible/python.yml --extra-vars "host=test1"

in hostfile I have this configuration:

[primary]
192.168.107.69
[standby]
192.168.107.70

I think that I should edit this file every time I want to run my playbook. so is it possible to have so many pairs of IPs?
for example something like this:

primary:1.1.1.1,standby:1.1.1.2
primary:1.1.1.3,standby:1.1.1.4
primary:1.1.1.5,standby:1.1.1.6  

or can I assign each pair the variable I want instead of writing it in my command every time? like:

primary:1.1.1.1,standby:1.1.1.2,host:test1
primary:1.1.1.3,standby:1.1.1.4,host:test2  

I searched a lot but I could't find anything and I'm new to ansible. Any suggestions?

Answer 1

Q: Is it possible to have a pair of IPs in Ansible?

A: Yes. It is possible. For example, it might be useful to create groups in the inventory with all pieces of information.

[primary]
1.1.1.1
1.1.1.3
1.1.1.5

[standby]
1.1.1.2
1.1.1.4
1.1.1.6

[ha]
1.1.1.1 stdby=1.1.1.2
1.1.1.3 stdby=1.1.1.4
1.1.1.5 stdby=1.1.1.6

It's possible to simplify the fetching of the configuration.

- hosts: primary, standby
  remote_user: root
  tasks:
  - name: copy the config to local
    fetch:
      src: /data1/cronjobs/gen_ddl
      dest: /AnsibleDir/conf

Without flat: yes the configuration files will be stored in

/AnsibleDir/conf/{{ inventory_hostname }}/data1/cronjobs/gen_ddl

Then it's possible to reference the configuration files by the inventory hostname. For example groups['primary'] (secondary the same way). Take a look at myshell_output and select the data for content and dest from the items

- hosts: 127.0.0.1
  connection: local
  remote_user: root
  tasks:
  - name: loop primary config
    command: "/AnsibleDir/driver.py
              /AnsibleDir/conf/{{ item }}/data1/cronjobs/gen_ddl"
    register: myshell_output
    loop: "{{ groups['primary'] }}"
  - name: copy the output to a local file
    copy:
      content: "{{ <SELECT-FROM-ITEM> }}"
      dest: "/AnsibleDir/output.{{ <SELECT-FROM-ITEM> }}"
    loop: "{{ myshell_output.results }}"

To reference primary/standby pairs use group ha. For example the play below changes the configuration both at primary and standby for all hosts in ha.

- hosts: ha
  tasks:
    - name: Change configuration at primary
      lineinfile:
        path: /AnsibleDir/conf/{{ inventory_hostname }}/data1/cronjobs/gen_dd
        regexp: <ADD-REGEXP>
        line: <ADD-LINE>
    - name: Change configuration at standby
      lineinfile:
        path: /AnsibleDir/conf/{{ hostvars[inventory_hostname].stdby }}/data1/cronjobs/gen_dd
        regexp: <ADD-REGEXP>
        line: <ADD-LINE>

Q: I need to find the differences of configuration files in 2 machines. they need to be the same. In python script, it will find the differences and fix them. So I need to have both configurations on my local then run the python script for them.

A: Fix the configuration files in 2 machines

- hosts: ha
  tasks:
    - name: Fix primary and standby config
      command: "/AnsibleDir/driver.py
                /AnsibleDir/conf/{{ inventory_hostname }}/data1/cronjobs/gen_ddl
                /AnsibleDir/conf/{{ hostvars[inventory_hostname].stdby }}/data1/cronjobs/gen_ddl"