Limited Time Offer!

For Less Than the Cost of a Starbucks Coffee, Access All DevOpsSchool Videos on YouTube Unlimitedly.
Master DevOps, SRE, DevSecOps Skills!

Enroll Now
Uncategorised

Ansible Template and Handlers explained with Example

August 26, 2023 comments off

We can declare variables in

  • playbook
  • inventory
  • commands

Which can be used & Intropolate only in playbook Tasks but not in the files used in playbook.

Solution: Template
Using Template module you can Intropolate vars mentioned in the files used in playbook.

Rule for using template Module

  • A file must be .j2 ext
  • Must use a module call “template”

Example Code for Cento/RHEL

---
- name: Update web servers
  hosts: web
  vars:
    myname: "Rajesh Kumar"

  tasks:
  - name: Install Apache in centos7
    ansible.builtin.yum:
      name: httpd
      state: latest
  - name: Copy index.html
    ansible.builtin.copy:
      src: index.html
      dest: /var/www/html/index.html
  - name: Template index.html
    template:
      src: index.html.j2
      dest: /var/www/html/index-template.html
  - name: Starting a Apache Server
    ansible.builtin.service:
      name: httpd
      state: started

index.html.j2

Project Requirement

  • When you Change APACHE STATIC HTML Content -> HTTPD restart is not required
  • When you Change APACHE Conf -> HTTPD restart is not required
  • HTTP should be run 90
  • No restart should be done on STATIC
  • Restart must be done at conf changes
---
- name: Update web servers
  hosts: web
  vars:
    myname: "Rajesh Kumar"
    httpport: 8090

  tasks:
  - name: Install Apache in centos7
    ansible.builtin.yum:
      name: httpd
      state: latest
  - name: Copy index.html
    ansible.builtin.copy:
      src: index.html
      dest: /var/www/html/index.html
  - name: Starting a Apache Server
    ansible.builtin.service:
      name: httpd
      state: started
  - name: stopped a Apache Server
    ansible.builtin.service:
      name: httpd
      state: stopped
  - name: Template for httpd.conf
    template:
      src: httpd.conf.j2
      dest: /etc/httpd/conf/httpd.conf
  - name: Starting a Apache Server
    ansible.builtin.service:
      name: httpd
      state: started

Example code for Template for Ubuntu

---
- name: Update web servers
  hosts: web
  vars:
    myname: "Rajesh Kumar"
    port: 81

  tasks:
  - name: Install Apache in Ubuntu
    ansible.builtin.apt:
      name: apache2
      state: latest
  - name: Copy index.html
    ansible.builtin.copy:
      src: index.html
      dest: /var/www/html/index.html
  - name: stopped a Apache Server
    ansible.builtin.service:
      name: apache2
      state: stopped
  - name: Template for httpd.conf
    template:
      src: ports.conf.j2
      dest: /etc/apache2/ports.conf
  - name: Starting a Apache Server
    ansible.builtin.service:
      name: apache2
      state: started

Problems

  • No change in config file but STOP and START happening

Solution

  • Handlers

What is Handlers?

  • A section is plyabook similar to tasks section
  • It contains multiple task similar to tasks section
  • The Handler task would execute when you call from tasks’s task
  • BUT one condition – ONLY when calling tasks’s task is CHANGED == TRUE
---
- name: Update web servers
  hosts: web
  vars:
    myname: "Rajesh Kumar"
    httpport: 8090

  tasks:
  - name: Install Apache in centos7
    ansible.builtin.yum:
      name: httpd
      state: latest
  - name: Copy index.html
    ansible.builtin.copy:
      src: index.html
      dest: /var/www/html/index.html
  - name: Starting a Apache Server
    ansible.builtin.service:
      name: httpd
      state: started
  - name: Template for httpd.conf
    template:
      src: httpd.conf.j2
      dest: /etc/httpd/conf/httpd.conf
    notify:
      - ReStarting a Apache Server

  handlers:
  - name: ReStarting a Apache Server
    ansible.builtin.service:
      name: httpd
      state: restarted

Handlers Code Example for Ubuntu

---
- name: Update web servers
  hosts: localhost
  vars:
    myname: "Rajesh Kumar"
    port: 81

  tasks:
  - name: Install Apache in Ubuntu
    ansible.builtin.apt:
      name: apache2
      state: latest
  - name: Copy index.html
    ansible.builtin.copy:
      src: index.html
      dest: /var/www/html/index.html
  - name: Template for httpd.conf
    template:
      src: ports.conf.j2
      dest: /etc/apache2/ports.conf
    notify:
      - ReStarting a Apache Server
  - name: Starting a Apache Server
    ansible.builtin.service:
      name: apache2
      state: started

  handlers:
  - name: ReStarting a Apache Server
    ansible.builtin.service:
      name: apache2
      state: restarted
Rajesh Kumar
Follow me
Latest posts by Rajesh Kumar (see all)