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"Ansible: The Swiss Army Knife of IT Automation"

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Shivam Anand
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3 min read

Ansible is an open-source automation tool that makes managing and setting up IT infrastructure simple. Ansible has grown in popularity among DevOps teams all around the world thanks to its straightforward yet effective methodology.

System administrators and DevOps teams may automate the provisioning, setup, and deployment of applications and infrastructure using the sophisticated automation tool Ansible. Users provide the intended state of the systems, and Ansible takes care of the processes required to get there, according to a declarative paradigm. Ansible communicates with remote systems via the SSH protocol and employs modules to carry out tasks.

Use Cases:

  • Provisioning of infrastructure and configuration administration orchestration and deployment of applications

  • Continuous deployment and integration (CI/CD)

  • Automation of security and compliance

  • Platform-agnostic cloud orchestration

  • Network configuration management and automation

Ansible Inventory:

Ansible's inventory files are text files that include a list of the target hosts or groups that will be the subject of an operation. It specifies the infrastructure inventory and permits the easy management of hosts by grouping them together. Either YAML or INI formatting can be used to write the inventory file.

Example : [ INI File ]

[webservers]
web1 ansible_host=192.168.0.10
web2 ansible_host=192.168.0.11

[databases]
db1 ansible_host=192.168.0.20

The inventory file allows administrators to organize hosts into logical groups and target specific groups for configuration management tasks. It also helps with parameterizing host-specific variables and managing complex infrastructure setups.

Example: To execute a playbook on all web servers defined in the inventory file, you can use the following command:

ansible-playbook -i inventory.ini playbook.yml --limit webservers

Ansible Config File:

The Ansible configuration file is used to customize Ansible's behavior and settings. It provides flexibility to configure various options according to specific requirements. The config file is usually located at /etc/ansible/ansible.cfg or in the project directory. Some of the most common parts of the config file are:

[defaults]: Contains general settings and configurations. [forks]: defines the number of parallel processes to use. [pw]: Allows specifying a password prompt behavior. [nocow]: Disables the copy-on-write optimization for file systems that support it. [transport]: defines the SSH connection and transport options. [library]: Specifies the path to custom Ansible modules. [private_key_file]: Sets the default private key file used for SSH connections.

Example: In the config file, if you set forks = 10 under the [defaults] section, it will execute up to 10 parallel processes during playbook execution.

Ad-hoc Commands:

Ad-hoc commands in Ansible allow administrators to perform quick tasks on remote hosts without creating dedicated playbooks. These commands are useful for one-time operations or troubleshooting tasks.

Example: To ping all hosts in the inventory file and check their reachability, you can use the following ad-hoc command:

ansible -m ping host1.example.com

Ansible Playbooks:

Playbooks in Ansible are written in YAML format and provide a way to express complex automation tasks. They consist of a set of plays that define the desired state of systems and the tasks required to achieve that state.

Why Playbooks:

  • Declarative: Playbooks allow expressing the desired state rather than specifying individual steps.

  • Reusability: Playbooks can be reused across different environments.

  • Idempotency: Ansible ensures that playbooks can be run multiple times without causing unintended side effects.

  • Orchestrated Execution: Playbooks provide the ability to sequence tasks and perform actions conditionally.

Example: The following is an example playbook to install MariaDB on remote hosts:

- hosts: databases
   become: true
   tasks:
     - name: Install MariaDB
       apt:
       name: mariadb-server
       state: present

Variables and Conditions:

Ansible allows the use of variables and conditions within playbooks to create dynamic and flexible automation. Variables can be defined at different levels, including global, group, and host-specific variables. Conditions such as 'when' can be used to control the execution of tasks based on specific criteria.

Example:

- hosts: webservers
  tasks:
    - name: Ensure Apache is installed
      apt:
      name: apache2
      state: present
   when: ansible_distribution == "Ubuntu"
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