Ansible powerful parameters - delegate_to, connection

 

Delegation to a host

Here is an example where we can delegate the task to a particular host. This play book is using inventory_hostname from the gather facts.

- name: Delegation to localhost
  hosts: all
  tasks:
  - name: create a file on target server
    file:
      path: /tmp/i_m_on_target_server.txt
      state: touch
  - name: create a file with host named file by delegation to localhost
    file:
      state: touch
      path: "/tmp/{{ inventory_hostname }}.txt"
    delegate_to: localhost

connection paramer

We can use this "connection" parameter add to your task level or play level.

# Filename: connection_local.yml 
# To do some task on ansible server
# local means  without doing ssh command (no need of  password and no need of ssh keys)
# with the local connection parameter for the play
---
- name: This is to determine how the connection parameter works  with local
  hosts: app
  connection: local
  gather_facts: false
  tasks:
  - name: connection local test
    file:
      state: touch
      path: /tmp/srirama.txt

local action

Now in the following example we will see how local_action will be working. The local_action is an Ansible module which will by pass the ssh connection to do command locally.

- name: Using local acion in this  playbook
  hosts: localhost
  vars: 
    test_file: /tmp/omnamahshivaya.txt
  tasks:
  - name: local action
    local_action: "command touch {{ test_file }}"
    

The better option to do it in local is using connection: local parameter at play level.