Ansible uses Jinja2 templating to modify files before they are distributed to managed hosts. Jinja2 is one of the most used templating engines for Python.
When a template for a file has been created, it can be deployed to the managed hosts using the template module, which supports the transfer of a local file from the control node to the managed hosts.
As an example of using templates you will change the motd file to contain host-specific data.
First in the ~/ansible-files/ directory create the template file motd-facts.j2:
Welcome to {{ ansible_hostname }}.
{{ ansible_distribution }} {{ ansible_distribution_version}}
deployed on {{ ansible_architecture }} architecture.
The template file contains the basic text that will later be copied over. It also contains variables which will be replaced on the target machines individually.
Next we need a playbook to use this template. In the ~/ansible-files/ directory create the Playbook motd-facts.yml:
---
- name: Fill motd file with host data
hosts: node1
become: yes
tasks:
- name: create MOTD file
ansible.builtin.template:
src: motd-facts.j2
dest: /etc/motd
owner: root
group: root
mode: 0644
You have done this a couple of times by now:
Understand what the Playbook does.
Execute the Playbook motd-facts.yml.
Login to node1 via SSH and check the message of the day content.
Log out of node1.
You should see how Ansible replaces the variables with the facts it discovered from the system.
Add a line to the template to list the current kernel of the managed node.
Do a grep -i for kernel
Change the template to use the fact you found.
Run the Playbook again.
Check motd by logging in to node1
[ec2-user@autoctl1 ansible-files]$ ansible node1 -m setup|grep -i kernel
"ansible_kernel": "3.10.0-693.el7.x86_64",
motd-facts.j2:Welcome to {{ ansible_hostname }}.
{{ ansible_distribution }} {{ ansible_distribution_version}}
deployed on {{ ansible_architecture }} architecture
running kernel {{ ansible_kernel }}.
node1.