Ansible playbook variables

we can declare and define a variable in playbooks.

1. within the file declaring and defining a variable

    vars:
        pName: tree
   

    ---
    - hosts: all
      connection: ssh
   
      vars:
        pName: tree
   
      tasks:
        - name: installing tree in slave-1
          action: yum name='{{pName}}' state=present
    ...
   

2. passing variable at runtime

    ---
    - hosts: all
      connection: ssh
   
      vars:
        pName: tree
   
      tasks:
        - name: installing tree in slave-1
          action: yum name='{{pName}}' state='{{xyz}}'
    ...
   
    one.yml
   

    ansible-playbook one.yml --extra-vars "pName=tree xyz=absent"
   

3. using different file

   set_fact ==> used to declare a variable in a file so that we can use that variable in other files.

   include ==> to execute a different file from the current file and also we can import variables.

    vim two.yml
    ---
      - set_fact: abc=tree
      - name: uninstalling from two
        yum:
          name: '{{abc}}'
          state: absent
    ...
   

vim one.yml
---
- hosts: all
  connection: ssh

  tasks:
    - include: two.yml
    - name: installing tree from one.yml
      action: yum name='{{abc}}' state=present
...

- include: two.yml --> first it goes to the two.yml and runs that file then it'll do the next operations in the current file.

Installing and starting service

here we are going to write a playbook to install httpd server and start the service.

service:
   name: httpd
   state: started

---
- hosts: all
  connection: ssh

  tasks:
    - name: installing https
      yum:
        name: httpd
        state: present
    - name: starting httpd
      service:
        name: httpd
        state: started
...

to start any service we need to use

service: name=<<service_name>> state=<<restarted/started>>

this can also be written as key-value pairs.