Introduction to Ansible

Ansible controls remote Linux systems centrally from a control node without installing an Ansible agent on them. You learn how managed nodes, inventory, connections, and modules interact and examine requirements for SSH and credentials. You then distinguish configuration management from provisioning and agent-based operating models.

The control node requires ansible-core and suitable connection data for managed systems. In the DevNinjas Dojo, our cloud learning environment, you install the package, configure SSH keys and inspect several managed nodes with Ansible’s ping module. You then examine selected ansible.cfg settings and distinguish the responsibilities of configuration files, inventory and command-line inputs.

The inventory describes managed systems and organizes them into logical groups. You create INI and YAML variants, group web and database hosts, and define host and group variables. Using nested groups plus group_vars and host_vars directories, you examine how to structure target selection separately from configuration data.

Ad hoc commands execute individual modules without a stored playbook. You use modules for packages, services, and files against selected inventory groups and inspect their parameters with ansible-doc. By repeating operations, you compare change status and idempotency without treating either as a general guarantee for every module or arbitrary shell command.

Playbooks describe plays and ordered tasks in YAML for clearly structured configuration workflows. You deliberately practice indentation, lists, and dictionaries and create a playbook for packages, users, and a configuration file. While running it with ansible-playbook, you examine target selection, module parameters, and the ok, changed, and failed statuses.

Variables can originate from inventory, playbooks, roles, or the command line and follow documented precedence rules. You compare selected sources, gather system information as facts, and store a task result with register. You then use that data in a later task and distinguish persistent definitions from results of the current playbook run.

Playbooks can select tasks from variables, facts, or earlier results and process data lists repeatedly. You combine when, loops, and handlers so a service is notified only after a task reports a change. With block and rescue, you structure related tasks and examine controlled error paths.

Host names, IP addresses, and ports can differ between environments; Jinja2 templates combine static configuration text with variables and facts that Ansible processes on the control node. You insert values, iterate over lists, and transform data with selected filters. In the learning environment, you develop an Nginx configuration for different hosts.

Ansible Vault encrypts variables and files so sensitive values are not stored as plaintext in a repository. You create encrypted content, use Vault IDs, and provide a password during playbook execution. You record that Vault protects data at rest, while decrypted values, output, and password sources require additional safeguards.

In a connected scenario, you install and configure Nginx with a playbook. Variables control its port and server name, a Jinja2 template generates configuration, a module handles firewall rules, and a handler responds to changes. You run the playbook together repeatedly and examine status and reachability.

Roles group tasks, handlers, variables, files, and templates in a known directory structure. You create a role with ansible-galaxy, move the web server playbook into it, and distinguish defaults from variables with higher precedence. You then use the role in a play and examine when role dependencies are suitable or unnecessarily coupled.

Ansible Galaxy distributes community content as roles and collections. You compare both formats, include prepared content through a requirements file, and install a collection. You distinguish the ansible.builtin collection included with ansible-core from separately installed collections and note that community content must be assessed against your own operational and security requirements before use.

Automation content can be inspected statically and evaluated before changes with check mode and diff. You run ansible-lint together against the project and compare a normal run with check mode and diff. You account for varying module support and recognize that these checks replace neither integration tests nor reviews.

The final project connects inventory groups, variables, templates, and roles across several Linux hosts. You structure a database, application server, and Nginx load balancer as separate responsibilities and run the combined playbook. You then deliberately examine dependencies and repeated execution without inferring production readiness or unlimited transferability.

Shared execution and governance can add further components beyond local playbooks. You distinguish the roles of AWX as an interface and API for automation jobs, execution environments as containerized runtime packages, and CI/CD as a possible trigger. You gain guidance on which topics matter for your automation journey without configuring AWX or a production pipeline.