In this post, we will review Ansible’s architecture and explore how it enables enterprise automation. We will also delve into the key architectural components of Ansible and how they interact with each other.
What we will cover:
Ansible is an open-source automation tool designed to simplify cloud provisioning workflows and reduce configuration management and deployment complexity across multiple systems. Its agentless architecture makes it easy to set up with low maintenance overhead for infrastructure.
Ansible is agentless, meaning it does not require any software installation on the managed systems. Instead, it uses YAML-based playbooks to describe automation tasks in a human-readable format. Playbooks allow for the composition of multi-tier deployments by modeling IT infrastructure relationships instead of managing individual systems.
For example, a basic Ansible automation might:
- Install and configure Apache on a fleet of servers
- Create users with specified permissions across multiple systems
- Deploy applications consistently across environments (dev, staging, production)
Organizations adopt Ansible for many use cases, such as automating repetitive tasks in workflows, managing deployments across multicloud environments, and maintaining configuration consistency across distributed systems.
Ansible can be used to provision cloud infrastructure, deploy complex web applications, and perform zero-downtime rolling updates. Its versatility makes it a preferred tool for setting up DevOps workflows and hybrid cloud automation.
Key features of Ansible
Ansible’s ability to unify automation across hybrid cloud environments makes it a solid open-source automation tool for modern enterprises. The sections below describe some of the main features contributing to Ansible’s current market position.
- Agentless architecture: Ansible doesn’t rely on agents to be installed on managed nodes. This design minimizes system resource usage and reduces maintenance overhead to simplify deployment across diverse environments.
- YAML-based playbooks: The automation workflows are written using playbooks, which use YAML syntax to define automation tasks. This approach makes automation scripts easy to read for admins without extensive programming expertise.
- Idempotence and predictability: Even if the playbook runs multiple times, Ansible ensures that tasks are executed without causing unwanted changes if the desired state is already achieved.
- Extensible framework: Ansible offers the flexibility to customize modules, plugins, and playbooks for infrastructure provisioning and application deployment. Its modular design supports the quick scaling of systems through automation.
- Cross-platform and dynamic inventory support: It supports multiple operating systems, including Linux, Windows, and macOS. Additionally, Ansible integrates with cloud providers and external APIs for dynamic inventory management across distributed environments.
Ansible offers a range of benefits that make it an essential tool for enterprises. Its agentless design and simple architecture reduce system complexity, while its flexibility supports diverse automation needs. Here are the benefits of using Ansible for enterprise automation:
- User-friendly interface: Ansible’s intuitive design and YAML-based playbooks reduce coding complexity for individuals. Developers can either use Python to automate tasks or utilize its straightforward interface for workflow automation.
- Open-source and free: Ansible is free to download and can be installed on Windows, Linux, and other operating systems. Enterprises can utilize Ansible modules without additional licensing costs.
- Flexible deployments: Its agentless architecture simplifies deployment across diverse environments. It supports on-premises, hybrid, and multicloud systems with consistent performance.
- Rapid adaptability: Its modular design and customizable components make it adaptable to any infrastructure configuration. It evolves with the existing system setup and offers long-term efficiency with high scalability.
- Comprehensive community support: Ansible’s vibrant community provides extensive resources, plugins, and solutions. This active ecosystem ensures access to continuous support and innovation.
The components of the Ansible architecture include:
- Control node: The system where Ansible is installed and from which all commands are run. orchestrates automation tasks across managed nodes over SSH (or WinRM for Windows).
- Managed nodes: No Ansible installation is required on the remote servers or devices that Ansible controls, keeping the system lightweight.
- Inventory: This is a file (usually INI, YAML, or dynamic source) that lists all managed nodes and groups them logically. It tells Ansible which machines to manage.
- Modules: Modules are small, reusable scripts that Ansible pushes to managed nodes to perform specific tasks like installing software, copying files, or restarting services. Ansible has hundreds of built-in modules and allows for custom module creation.
- Playbooks: These are YAML files that define the desired automation tasks and configurations. Playbooks organize multiple tasks into a structured workflow.
- Plugins: Plugins extend Ansible’s core functionality, including connection types, callback output formats, and action behaviors.
- Roles: Roles are a standardized way to organize playbooks and related files into reusable, modular units with predefined file structure (tasks, handlers, variables, templates, etc.). Read more: Basics, Creating & Using Ansible Roles
- The automation workflows can either be triggered manually or as part of some CI/CD pipeline, for efficient deployments and configuration management across distributed systems.
How does a deployment in Ansible work?
As we have seen, Ansible is built to deliver efficient automation while maintaining simplicity. It operates without the need for centralized servers or agents on managed nodes.
Instead, it utilizes standard communication protocols like SSH or WinRM. The architecture includes key components like the control node, managed nodes, inventory, playbooks, modules, plugins, and more.
Ansible fetches configuration details and tasks from version control systems (VCS). It processes playbooks on the control node to identify the corresponding inventory and execute tasks using modules and plugins. This modular approach provides flexibility and scalability for diverse environments.
The following diagram provides an overview of a general Ansible deployment.
The sections below provide detailed descriptions of the individual components above so that you can understand how they interact to automate configuration management and deployment workflows.
1. Control node
As the name suggests, the control node is the central system where Ansible is installed and configured. It is the Ansible architecture’s main component for managing and executing all automation workflows.
The control node processes playbooks and pushes modules to managed nodes to perform defined tasks. It also handles inventory and interacts with plugins to extend functionality as needed.
2. Managed nodes
Managed nodes are the systems where Ansible performs its automation tasks. Typically, they are servers where applications and business services are hosted. These nodes act as targets that the control node manages and communicates with during automation workflows.
Managed nodes do not need any additional software or agents installed. Instead, the control node connects to them using standard protocols like SSH for Linux systems or WinRM for Windows systems. Ansible runs temporary scripts (modules) to achieve the desired state through these managed nodes.
3. Ansible Core
Ansible Core is the engine that powers automation by processing playbooks and coordinating task execution. It provides the architectural framework for Ansible and includes essential tools like ansible-playbook and ansible-doc for driving workflows. The engine establishes efficient communication between the control node and managed nodes to manage execution seamlessly.
Ansible Core includes support for the Ansible language, which uses YAML to define automation rules and workflows in playbooks. It supports advanced functionalities like conditionals and loops to simplify complex automation processes.
Ansible Core also allows for extensions through plugins and modules.
With significant updates released twice a year, Ansible Core evolves to prioritize simplicity and reliability while supporting modern IT automation.
4. Inventory
Ansible identifies and defines a logical group of target systems in the form of an inventory. It uses this inventory to organize target nodes and group them for easy management. The inventory can be a simple file listing managed nodes and their roles.
For example, you might group web servers, databases, or application hosts in one inventory. Inventory allows you to specify tasks for groups or individual hosts to streamline automation workflows. You can also assign group-level or host-level variables to customize task execution.
The inventory file is located at path /etc/ansible/hosts by default, but users can specify custom files. Larger environments may require organizing hosts into multiple files or directories.
Inventory can include static files or dynamically sourced data. This flexibility ensures that Ansible can handle small and large-scale infrastructures using various formats, such as INI and YAML.
What is a dynamic inventory?
A dynamic inventory connects to external data sources and APIs to fetch real-time information about managed nodes. Instead of static files, dynamic inventory plugins query platforms like AWS, Azure, or OpenStack to retrieve updated information.
It eliminates the need for manual updates and supports scalable and ephemeral environments. It also supports hybrid models combining cloud data with static files to manage complex and distributed environments. This is critical for scaling in cloud-native environments, where IP addresses and resources change frequently.
5. Ansible playbooks
Ansible playbooks are YAML files that define and orchestrate automation tasks in a structured and human-readable format. Each playbook contains one or more plays, each targeting a specific group of hosts and performing tasks. Playbooks support parallel task execution for managing the order of operations more smoothly and effortlessly.
A playbook comprises key elements like hosts, tasks, and modules, which work together to achieve the desired state. For example, a playbook can define tasks to install and configure a web server, as seen in the example below.
---
- name: Configure web servers
hosts: webservers
tasks:
- name: Install Apache
yum:
name: httpd
state: present
- name: Start Apache service
service:
name: httpd
state: startedIn this playbook, the “hosts” keyword specifies the “webservers” as the target group. The tasks section defines actions such as installing and starting the Apache service. Likewise, we can configure the playbooks to execute different tasks.
6. Module
Modules, also called “task plugins” or “library plugins,” are standalone units of code that perform specific tasks. Examples include modules like copy, yum, user, and service.
Modules are what Ansible calls when you run tasks, and they define the “what to do” logic. They are typically idempotent, so rerunning them does not change the system unnecessarily. For example, the file module manages file attributes like permissions, ownership, or state (present/absent).
Modules can be executed directly from the Ansible CLI or as part of a playbook task.
Each module accepts arguments in key-value pairs or YAML syntax as complex arguments. For example, the command module can reboot a server using a direct command-line approach or a playbook task.
Modules are designed to be idempotent so that they don’t make changes if the system is already in the desired state. They can trigger change events in playbooks and notify handlers to execute additional tasks.
7. Module utilities
Module utilities are shared libraries that avoid code duplication and streamline custom automation workflow development. They handle repetitive tasks like input parsing and output formatting.
Here are some of the available module utilities in Ansible:
- Basic utilities: The basic.py utility provides core functionalities like argument validation and response handling. It serves as the foundation for most Python-based Ansible modules.
- URL utilities: The urls.py module utility supports HTTP and HTTPS requests. It simplifies operations like parsing URLs and handling API calls.
- File utilities: The common/file.py utility provides helper functions for file management tasks, such as reading, writing, and verifying file properties.
- Dictionary utilities: The common/dict_transformations.py utility offers functions for manipulating and transforming dictionaries. It simplifies operations like merging and filtering data structures.
- Custom utilities: Developers can create custom utilities in the module_utils directory to centralize shared functionality. These utilities are dynamically included during playbook execution.
The module utilities are written in Python or PowerShell to maintain code compatibility across diverse environments. With most modules now hosted in collections, Ansible enables a modular and scalable approach to automation.
8. Plugins
Plugins are components in Ansible that extend its core functionality to enable greater flexibility and customization in automation. These small pieces of Python code augment Ansible’s capabilities to add custom logic and features.
Here are some of the key plugin types in Ansible:
- Action plugins: Action plugins integrate local processing with module functionality. They allow modifications to modules return data or additional local operations before executing a module.
- Callback plugins (like
defaultorjson): Callback plugins respond to specific events in Ansible, such as controlling output during execution. They enable custom logging or notifications. - Connection plugins (like
sshordocker): These plugins manage communication between the control node and managed nodes. They support protocols like SSH, WinRM, and HTTP. - Inventory plugins (like
aws_ec2): Inventory plugins enable dynamic and static inventory management. They allow integration with sources like cloud providers or custom APIs to fetch host data dynamically. - Lookup plugins: Lookup plugins retrieve data from external sources such as files, databases, or APIs. They populate variables during playbook execution.
With a wide range of built-in plugins and the ability to create custom ones, Ansible provides an adaptable and extensible architecture for diverse automation requirements. Plugins operate on the control node and can be used across multiple modules. They adhere to strict configuration and coding standards to ensure compatibility and functionality.
9. Roles
Ansible roles are a structured way to organize Ansible playbooks, making complex configurations more modular, reusable, and maintainable. A role groups together related tasks, variables, templates, files, and handlers into a standardized directory layout, allowing you to automatically load these elements when the role is applied.
Each role typically includes subdirectories like:
tasks/for task definitions (main.yml is usually the entry point)vars/for variablesdefaults/for default variablesfiles/for static filestemplates/for Jinja2 templateshandlers/for restart or notification handlersmeta/for role dependencies
When a playbook uses a role, it can be referenced simply by name, keeping the playbook clean and readable.
An Ansible module is a standalone, reusable unit of code used to perform specific tasks during playbook execution, whereas module utilities are shared Python libraries that modules can import to avoid duplicating common functionality.
- Purpose: Modules directly perform actions on managed nodes, while module utilities support modules by providing reusable functions. Modules execute independently, but module utilities act as shared libraries, helping multiple modules avoid code duplication.
- Execution: Modules are task-specific and invoked during playbook execution, whereas module utilities are dynamically loaded to assist with background operations like input validation and output formatting.
- Scope: Modules focus on task execution, while module utilities enhance development efficiency and ensure consistency across multiple modules.
- Language support: Modules can be written in any language that outputs JSON, while module utilities are primarily written in Python or PowerShell for Ansible compatibility.
Ansible modules and Ansible plugins serve different roles within the automation framework, although both extend Ansible’s capabilities. In short, modules perform actions on target systems, while plugins modify or extend Ansible’s behavior during a playbook run. You typically invoke modules directly in playbooks, whereas plugins operate more invisibly unless specifically configured.
- Purpose: Plugins extend Ansible’s core functionality by adding custom logic and features, while modules execute defined tasks through managed nodes.
- Execution: Modules can execute tasks only on managed nodes during playbook runs and interact directly with the target systems. On the other hand, plugins operate on the control node to offer background support for processes like logging and data transformation.
- Customization: Modules can be written in any language that outputs JSON. However, plugins must be written in Python to integrate seamlessly with Ansible’s plugin architecture.
- Interaction: Modules are task-driven and invoked directly in playbooks or from the command line. Plugins operate passively to augment Ansible processes by handling specific events or providing additional functionality.
The Ansible Command-Line Interface (CLI) is a powerful suite of tools that helps users automate tasks efficiently. It is task-oriented, supporting everything from basic administrative duties to complex automation workflows.
Ansible CLI offers a range of specialized utilities:
- ansible: Execute ad hoc commands across managed nodes
- ansible-playbook: Run structured playbooks to automate workflows
- ansible-config: Review and manage Ansible configurations
Each tool serves a specific function, enabling users to manage inventory, configure settings, and execute automation tasks with precision.
Ansible CLI tools are versatile and enable both ad hoc and persistent automation.
For instance:
- ansible-galaxy: Download and manage community roles and collections.
- ansible-pull: Allow nodes to pull configuration updates directly from source control.
Each utility includes a range of parameters and options, offering users fine-grained control and ensuring a modular, scalable approach to automation.
With the addition of Ansible Navigator, users gain a command-line and TUI (text user interface) for running automation content within execution environments. This enhances organization and simplifies the management of Ansible operations.
Spacelift’s vibrant ecosystem and excellent GitOps flow are helpful for managing and orchestrating Ansible. By introducing Spacelift on top of Ansible, you can easily create custom workflows based on pull requests and apply any necessary compliance checks for your organization.
Another advantage of using Spacelift is that you can manage infrastructure tools like Ansible, Terraform, Pulumi, AWS CloudFormation, and even Kubernetes from the same place and combine their stacks with building workflows across tools.
Our latest Ansible enhancements solve three of the biggest challenges engineers face when they are using Ansible:
- Having a centralized place in which you can run your playbooks
- Combining IaC with configuration management to create a single workflow
- Getting insights into what ran and where
Provisioning, configuring, governing, and even orchestrating your containers can be performed with a single workflow, separating the elements into smaller chunks to identify issues more easily.
Would you like to see this in action, or just get a tl;dr? Check out this video showing you Spacelift’s Ansible functionality:
If you want to learn more about using Spacelift with Ansible, check our documentation, read our Ansible guide, or book a demo with one of our engineers.
Ansible is a configuration management and orchestration platform that simplifies IT automation with its agentless architecture and human-readable configuration files. Its modular design and extensible features make it a versatile tool for managing multicloud and hybrid environments.
In this post, we discussed the core components of any Ansible implementation, which work seamlessly to enable comprehensive automation tasks across diverse infrastructures.
The extensible nature of Ansible has encouraged the growth of a community that actively contributes to innovative solutions, delivering complex automation workflows. Whether managing cloud resources or deploying applications, the flexible Ansible architecture easily accommodates requirements to streamline diverse IT operations.
Manage Ansible better with Spacelift
Managing large-scale playbook execution is hard. Spacelift enables you to automate Ansible playbook execution with visibility and control over resources, and seamlessly link provisioning and configuration workflows.
