Ansible localhost & delegate_to: Run Tasks on Control Node Guide — Video Tutorial

How to run Ansible tasks on localhost. Use connection local, delegate_to localhost, and local_action to execute on the Ansible control node.

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Tutorial summary

What you'll learn

How to Execute command on the Ansible host?
Execute command on the Ansible host options
Links
code
execution
idempotency
Conclusion
Methods to Run on Localhost
Method 1: hosts: localhost
Method 2: delegate_to localhost

How to Execute command on the Ansible host? When Ansible becomes part of your daily workflow it is natural you would like to automate also task in your local machine. Execute command on the Ansible host options - `connection plugin` - `delegate_to: localhost` - `local_action` There are three ways to execute modules and commands on the Ansible Controller host. The first and my favorite is using the connection plugin `local` and applying it to the Ansible Play level of your Playbook. The tricky was is to adjust some ansible variables about the python interpreter. I consider it the best way nowadays. The second way is using the `delegate_to` at the Task level. This has the advantage to delegate only one task to localhost but still needs only the implicit localhost scheme. The third way is using the `local_action` statement. I personally don't like it but it's one alternative as well at Task level, so same as the previous. Links - [Controlling where tasks run: delegation and local actions](https://docs.ansible.com/ansible/latest/user_guide/playbooks_delegation.html) - [Implicit ‘localhost’](https://docs.ansible.com/ansible/latest/inventory/implicit_localhost.html) ## Playbook How to Execute command on the Ansible host using connection: local method. code ```yaml --- - name: localhost Playbook hosts: localhost vars: ansible_connection: local ansible_python_interpreter: "{{ ansible_playbook_python }}" tasks: - name: print hostname ansible.builtin.debug: msg: "{{ inventory_hostname }}" ``` execution ```bash ansible-pilot $ ansible-playbook ansible\ statements/localhost.yml [WARNING]: No inventory was parsed, only implicit localhost is available [WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all' PLAY [localhost Playbook] ***************************************************************************** TASK [Gathering Facts] **************************************************************************** ok: [localhost] TASK [print hostname] ***************************************************************************** ok: [localhost] => { "msg": "localhost" } PLAY RECAP **************************************************************************************** localhost : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0 ansible-pilot $ ``` idempotency ```bash ansible-pilot $ ansible-playbook ansible\ statements/localhost.yml [WARNING]: No inventory was parsed, only implicit localhost is available [WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all' PLAY [localhost Playbook] ***************************************************************************** TASK [Gathering Facts] **************************************************************************** ok: [localhost] TASK [print hostname] ************************************

About this tutorial

Author: Luca Berton
Difficulty: Beginner
Read time: 8 min
Category: installation

Topics covered

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