Question on the multiple loop structure in my playbook

[Deepak B K]

Hi All , 

I trying to modify the sshd_config  parameter using the lineinfile  ansible module . I would like to delegate this to multiple host . As we have used the loop twice its unable to resolve the loop structure.

vars:
ssh_delegate_hosts:
  - "192.50.26.248"
  - "192.50.27.248"

- name: Change configuration in sshd_config

  ansible.builtin.lineinfile:
    path: /etc/ssh/sshd_config
    regexp: "{{ item.regexp }}"
    line: "{{ item.line }}"
  loop:
    - { regexp: '^AllowTcpForwarding', line: 'AllowTcpForwarding yes' }
    - { regexp: '^AllowAgentForwarding', line: 'AllowAgentForwarding yes' }
  loop: "{{ ssh_delegate_hosts }}"
  delegate_to: "{{ item }}"

Need your valuable  feedback  of how  to loop both  the lines and loop the hosts . 

Thanks and Regards,

Deepak Kumar

[Will McDonald]

You haven't described the actual overarching thing you're trying to do with this, sometimes describing the larger task can be useful in terms of providing better guidance. 

But reading between the lines, is there any reason you can't place your intended delegation hosts into an inventory group and address them directly? For example if they're getting special treatment as intended jumphosts or similar. Group them accordingly and run the bits of automation that's unique to that intended system role against those group members.

I'd also tend to prefer a Jinja template over lineinfile for config if possible especially if you need to accommodate different conditional scenarios. It's potentially a little more effort to start, but will save you pain in the long run.

That said, I think you can probably achieve what you're trying to do with a product filter? (There's probably easier ways to get the outcome you want too.)

https://www.packetswitch.co.uk/how-to-use-ansible-loops-with-examples/

https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_loops.html#iterating-over-nested-lists

Here's a simplified example, you'd need to modify slightly to pull out the specific elements:

- name: debug vars
  hosts: localhost
  gather_facts: no

  vars:
    delegates:
      - host1
      - host2
    regexes:
      - regex: AllowTcpForwarding
        line: AllowTcpForwarding yes
      - regex: AllowAgentForwarding
        line: AllowAgentForwarding yes

  tasks:
    - name: Do some stuff
      debug:
        msg: "Doing {{ item.1 }} on {{ item.0 }}"
      delegate_to: "{{ item.0 }}"
      loop: "{{ delegates | product(regexes) | list }}"

Which would do:

(ansible)$ ansible-playbook test/debug.yml

PLAY [debug vars] ******************************************************************************************************

TASK [Do some stuff] ***************************************************************************************************
ok: [localhost -> host1] => (item=['host1', {'regex': 'AllowTcpForwarding', 'line': 'AllowTcpForwarding yes'}]) => {
    "msg": "Doing {'regex': 'AllowTcpForwarding', 'line': 'AllowTcpForwarding yes'} on host1"
}
ok: [localhost -> host1] => (item=['host1', {'regex': 'AllowAgentForwarding', 'line': 'AllowAgentForwarding yes'}]) => {
    "msg": "Doing {'regex': 'AllowAgentForwarding', 'line': 'AllowAgentForwarding yes'} on host1"
}
ok: [localhost -> host2] => (item=['host2', {'regex': 'AllowTcpForwarding', 'line': 'AllowTcpForwarding yes'}]) => {
    "msg": "Doing {'regex': 'AllowTcpForwarding', 'line': 'AllowTcpForwarding yes'} on host2"
}
ok: [localhost -> host2] => (item=['host2', {'regex': 'AllowAgentForwarding', 'line': 'AllowAgentForwarding yes'}]) => {
    "msg": "Doing {'regex': 'AllowAgentForwarding', 'line': 'AllowAgentForwarding yes'} on host2"
}

PLAY RECAP *************************************************************************************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

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[Deepak B K]

Thank you very much  you have in detail  describe to handle multiple loops by using the product and list  in the ansible playbook . Basically this was a admin script out of box requirements as we are not include in our repository so that  the reason we could not leverage the out environmental inventory. 

Once again Thank you so much .. I appreciate the help .

Thanks 

Deepak Kumar