Restarting httpd Service in idempotence nature

Idempotence: Idempotence means that applying an operation once or applying it multiple times has the same effect. Examples: Multiplication by zero. No matter how many times you do it, the result is still zero.

When we make any changes to configuration files then only we restart any service. If we are executing a command to restart the service it will consume compute resources.

When we run ansible-playbook for restarting the service of httpd. It will again restart the service at the target node but we want the service to only restart when we make any change to configuration files otherwise it will not restart the service of httpd and save the compute resources.

notify

List of handlers to notify when the task returns a ‘changed=True’ status.

handlers module in ansible

Sometimes we want a task to run only when a change is made on a machine. For example, We may want to restart a service if a task updates the configuration of that service, but not if the configuration is unchanged. Ansible uses handlers to address this use case. Handlers are tasks that only run when notified.

Here is the complete playbook for the following:

- hosts: all
  vars_files:
  - http_var.yml
  #vars_prompt:
  #- name: dvd_dir
   # private: no
 # vars:
 # - dvd_dir: "/dvd1"
 # - docroot: "/var/www/lw"
 # - http_port: 8080
  tasks:
  - file: 
     state: directory
     path: "{{ dvd_dir }}"
  - name: "mounting dvd"
    mount:
     src: "/dev/cdrom"
     path: "{{ dvd_dir }}"
     state: mounted
     fstype: "iso9660"
  - name: "Setting yum repo"
    yum_repository:
     baseurl: "{{ dvd_dir}}/AppStream"
     name: "mydvd1"
     description: "yum1"
     gpgcheck: no
  - name: "setting 2nd yum repo"
    yum_repository:
     baseurl: "{{ dvd_dir }}/BaseOS"
     name: "mydvd2"
     description: "yum2"
     gpgcheck: no
  - name: "installing httpd"
    package:
     name: "httpd"
     state: present
  - name: "creating lw directory inside /var/www/"
    file: 
     state: directory
     path: "{{ docroot }}"
  - template:
     dest: "/etc/httpd/conf.d/lw.conf"
     src: "lw.conf"
    notify: 
     - Restart httpd
  - copy: 
     dest: "{{ docroot }}/index.html"
     content: "this website has been configures using Ansible"
  - name: "restarting the httpd service"
    service:
     name: "httpd"
     state: restarted
     enabled: yes
  - name: "Setting up Firewall on port: {{ http_port }}"
    firewalld:
     port: "{{ http_port }}/tcp"
     state: enabled
     permanent: yes
     immediate: yes
  - handlers: 
    - name: Restart httpd
      service: 
        name: "httpd"
        state: started
        enabled: yes

Attaching the variables file:

dvd_dir: "/dvd1"
docroot: "/var/www/html"
http_port: 8080

Attaching the configuration file:

Listen {{ http_port }}
<VirtualHost {{ ansible_facts['default_ipv4']['address'] }}:{{ http_port }}>
DocumentRoot {{ docroot }}
</VirtualHost>

Github Repository: https://github.com/ankit98040/Ansible_playbooks

Thank You for reading.