Ansible is composed of several key components that work together to automate IT tasks like configuration management, application deployment, and orchestration. Below are the main components of Ansible:
Definition: A list of managed nodes (hosts) that Ansible will operate on.
Static Inventory: A simple text file that lists the hosts and groups of hosts. Each host can be associated with variables.
Dynamic Inventory: For environments that change frequently (e.g., cloud environments), a dynamic inventory can be generated using scripts or plugins that query external sources (like AWS, Google Cloud, etc.).
Definition: Playbooks are files written in YAML that define a series of tasks to be executed on the remote hosts.
Structure: Playbooks consist of multiple plays, where each play applies tasks to a group of hosts. They are the heart of Ansible and describe what actions should be performed in a human-readable format.
Idempotency: Playbooks are designed to be idempotent, meaning running the same playbook multiple times will yield the same results.
Definition: Modules are the units of work in Ansible. They perform tasks like managing packages, services, files, databases, users, networks, etc.
Built-in Modules: Ansible comes with a large set of built-in modules that support various tasks like system administration, cloud provisioning, and network configuration.
Custom Modules: Users can write their own modules for custom tasks or extend Ansible’s functionality.
Definition: Tasks are the individual actions defined within a playbook. A task uses a module to perform a specific action, such as installing software, managing files, or restarting services.
Execution: Tasks are executed in sequence, and their success or failure is determined before moving on to the next task.
Definition: Roles are a way of organizing playbooks into reusable and modular components. Each role consists of tasks, files, templates, and variables.
Structure: Roles have a predefined directory structure, making it easy to organize and reuse playbooks across different projects or environments.
Definition: A play is part of a playbook that defines the hosts and the tasks to be executed. It maps the hosts to roles or tasks, determining which machines will run which tasks.
Goal: Each play is designed to accomplish a specific goal, like installing software or configuring a service, on a group of hosts.
Definition: Templates are files that contain placeholders for variables. Ansible uses the Jinja2 templating engine to generate configuration files dynamically.
Usage: Templates allow for flexible configuration management by enabling the creation of files with dynamic values based on variables.
Definition: Handlers are special tasks that are triggered only when notified by other tasks.
Example: If a task updates a configuration file, it might notify a handler to restart a service to apply the changes.
Definition: Variables allow dynamic content to be passed into tasks, templates, and playbooks.
Scope: Variables can be defined at various levels, such as host-specific, group-specific, role-specific, or global, and can also be passed via the command line or inventory.
Definition: Facts are system variables that are automatically discovered by Ansible when it connects to a managed node.
Usage: These facts provide information about the system, such as IP address, OS type, memory, and more. They are used in playbooks to conditionally run tasks based on the system’s state.
Definition: Plugins are small pieces of code that augment Ansible's core functionality.
Types: There are several types of plugins, including:
Callback Plugins: Modify Ansible’s output or run specific actions during playbook execution.
Connection Plugins: Handle communication between Ansible and managed nodes.
Action Plugins: Extend Ansible’s actions beyond modules.
Lookup Plugins: Enable tasks to retrieve data from external sources.
Filter Plugins: Enable additional logic to be applied when using variables in templates and playbooks.
Definition: Ansible Vault is a feature that allows for the encryption of sensitive data (like passwords or keys) in playbooks or files.
Usage: Ansible Vault ensures secure handling of secrets and confidential information within the automation process.
Definition: This is where Ansible runs. By default, it’s a simple Python environment, but it can be customized using containers or other virtualized environments for specific use cases.
Definition: Ansible Galaxy is a community platform where users can share and download pre-built roles. It serves as a repository for finding reusable roles and collections for different use cases.