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By Daniel Tanque16 de Novembro, 2023In Sem categoria

Ansible (Conditionals, Loops and Roles)

In the realm of IT automation, Ansible stands out as a powerful and versatile tool, empowering IT professionals to streamline complex tasks and manage infrastructure with ease. At the heart of Ansible’s capabilities lie three fundamental concepts: conditionals, loops, and roles. These building blocks work in harmony to enable granular control over automation processes, ensuring that tasks are executed only when necessary, repeated efficiently, and organized in a structured manner.

Ansible Conditionals:

Conditionals in Ansible allow you to execute tasks based on certain conditions. Ansible supports a variety of conditionals, including:

  • when: The when keyword is commonly used for conditional execution. It allows a task to be executed only if a specified condition is true.
  • failed_when: This allows you to specify conditions under which a task should be considered failed.
  • changed_when: This sets conditions under which Ansible considers a task to have “changed,” affecting how it reports the success or failure of the task.

For example you have to install a package, but for Debian we use apt, for Red Hat we use yum. You can set conditions based on OS:

– name: Install NGINX
hosts: all
– name: Install NGINX on Debian
name: nginx
state: present
when: ansible_os_family == “Debian” and ansible_distribution_version == “16.04”
– name: Install NGINX on Red Hat
name: nginx
state: present
when: ansible_os_family == ” Red Hat” or ansible_os_family == “SUSE”

Ansible Loops:

Loops in Ansible allow you to repeat a task or a set of tasks multiple times. There are different ways to implement loops in Ansible, including:

  • with_items (deprecated in Ansible 2.5+): It is used to iterate over a list of items.
  • loop (Ansible 2.5 and newer): A more generic way to loop over any list or dictionary.

For Example a conditional within loops:

– name: Check status of a service and send an email
hosts: localhost
– command : service httpd status
register : result
– mail :
to : < email >
subject : Service Altert
body : Httpd service is down
when: result.stdout.find(‘down’) != -1

– name: Install Softwares
hosts: all
– name: nginx
required: True
– name: mysql
required: True
– name: apache
required: False
– name: Install “{{ }}” on Debian
name: “{{ }}”
state: present
when: item.required == True
loop: “{{ packages }}”

Ansible Roles:

Roles in Ansible are a way of organizing and structuring your playbooks. A role is essentially a collection of tasks, variables, and templates that can be easily reused across multiple playbooks. Roles help in modularizing and organizing your automation code.

Roles directory structure:

  • tasks: Contains the main list of tasks to be executed by the role.
  • handlers: Contains handlers, which are tasks that only run when notified by other tasks.
  • templates: Contains template files that can be used by tasks.
  • vars: Contains variables that can be used by tasks.
  • defaults: Contains default variables for the role.
  • meta: Contains metadata about the role (e.g., dependencies).

There are many roles already made and available to use at Ansible-Galaxy, to setup your system. To find roles you can go through the Ansible website, but also through terminal:

ansible-galaxy search <name of the role>

To use a specific role:

ansible-galaxy install <name of the role>

By default it goes to /etc/ansible/roles, but can be changed at /etc/ansible/ansible.cfg

svgData Structures

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