comparisons Ansible vs Terraform

KodeKloud · April 22

Cloud Computing has transformed the IT industry by simplifying IT infrastructure management. With Cloud Computing, organizations can easily provision and scale resources as needed without worrying about the underlying infrastructure. Two of the most commonly used tools for infrastructure management and provisioning are Ansible and Terraform.

This article discusses what each of the two tools does, their key features, and how they compare in the IaC world.

Understanding Ansible

Ansible is an open-source automation tool developed by Red Hat that simplifies complex IT tasks. Its agentless architecture automates configuration management and application deployment on remote machines using SSH and WinRM protocols.

Ansible uses declarative language to define its desired state for any system. Instead of providing step-by-step instructions, users describe an end state they'd like their system to reach, leaving Ansible to determine the most efficient route toward that goal. This approach enhances simplicity and readability in Ansible's configuration files (called playbooks).

Key Features of Ansible:

Agentless Architecture: Ansible does not deploy agents, i.e., it does not require extra software on the target machines. This makes its setup easier and mitigates problems such as out-of-date agents, which are a common problem with agent-based solutions.

YAML-based Playbooks: Ansible playbook scripts are written in YAML, making them easy to read for humans and understandable without much expertise. Playbooks define a set of tasks to be executed on managed nodes to achieve the desired state.

Idempotent Execution: The Ansible tasks are idempotent, which means that applying the same configuration multiple times yields identical results as applying it just once. This ensures systems stay in their desired states even if repeated configurations are applied, helping prevent infrastructure configuration drift.

Extensible: Ansible is highly extensible, supporting custom modules and plugins explicitly created to integrate seamlessly into existing infrastructure or workflows. This extensibility enables Ansible to meet individual users' requirements with ease.

Integration: Ansible integrates easily with popular version control systems such as Git, enabling engineers to combine infrastructure configurations with application code to provide visibility and enable collaboration.

To learn more about playbooks, check out this blog: What is Ansible Playbook and How to Write it?

Understanding Terraform

Terraform is a popular open-source tool developed by HashiCorp that enables users to manage infrastructure as code. It provides support for multiple cloud providers, including Amazon Web Services, Microsoft Azure, Google Cloud Platform, and more.

Terraform users write declarative configuration files in HCL to define and provision infrastructure resources like virtual machines, storage accounts, and network configurations. This makes it easier for teams to collaborate and manage infrastructure changes in a safe and consistent manner across different cloud providers.

Key Features of Terraform:

Infrastructure as Code: Terraform enables infrastructure to be defined using code, which can be versioned, shared, and reused like any other software artifact. This approach brings consistency and repeatability to infrastructure provisioning.

Declarative Configuration: Similar to Ansible, Terraform follows a declarative approach. Users specify the desired state of their infrastructure in configuration files, and Terraform determines the actions necessary to reach that state.

Provider Ecosystem: Terraform supports a vast ecosystem of providers, including major cloud providers like AWS, Azure, and Google Cloud and numerous third-party providers for services like Kubernetes, Docker, and more. This allows users to manage heterogeneous environments using a single tool.

Plan and Apply Workflow: Terraform employs a two-step workflow consisting of "plan" and "apply" phases. During the "plan" phase, Terraform generates an execution plan describing its actions to achieve the desired state. In the "apply" phase, Terraform executes the plan, making the necessary changes to the infrastructure.

State Management: Terraform maintains a state file that records the current state of the infrastructure. This state file is used to map real-world resources to the configuration, track dependencies, and plan future changes. Proper state management is crucial for ensuring the integrity of infrastructure changes.

Ansible vs. Terraform: Key Differences

Now that we have a basic understanding of Ansible and Terraform, let's compare them across several key dimensions:

Use Cases

Ansible excels in configuration management by automating the setup and maintenance of servers and infrastructure components at scale. Whether it's configuring software, adjusting system parameters, or managing file systems, Ansible simplifies the complexities associated with maintaining a large and diverse IT environment.

Terraform focuses mainly on infrastructure provisioning and management. It is the best choice for defining, controlling, and managing cloud resources, such as infrastructure components and services from different providers. Terraform is usually used for situations where infrastructure is transient and needs to be provisioned dynamically.

Language and Syntax

Ansible sets up playbooks in YAML, a format famous for its simplicity and readability. This makes playbooks easy to understand for both beginners and extensively experienced users.

In Terraform, users define infrastructure using HCL or JSON. HCL not only handles infrastructure configuration situations but also provides features such as interpolation and resource blocks for defining resources.

Execution Model

Ansible uses a push-based model, where the control node is responsible for transmitting commands and configurations via SSH to the targeted nodes. This model is perfect for orchestrating tasks in multiple systems and can even grow to thousands of nodes.

Terraform uses a pull-based model, where each target node independently pulls its configuration from a source like a version control repository. This model allows organizations to maintain greater control over their infrastructure and ensures that changes are made consistently and reliably.

Resource Abstraction

Ansible splits infrastructure operations into individual tasks, which are then run sequentially, one after another, on the target nodes. Though Ansible offers you modules for managing cloud resources, network devices, and so on, it does not outline resource modeling as built-in as Terraform does.

The Terraform stack uses a declarative configuration language that allows users to explicitly define dependencies, relationships, and provisioning logic. Adapting this approach helps manage complex IT infrastructure more flexibly and predictably.

Ecosystem and Integrations

Ansible leverages a comprehensive set of modules, roles, and integrations to make the configuration process even easier. It synchronizes perfectly with cloud services such as AWS, Azure, or Google Cloud.

Terraform integration works by utilizing provider plugins, which are responsible for managing resources and communicating with the provider's API. When you define your infrastructure with Terraform, you specify the resources you want to create, and Terraform uses the provider plugin to create those resources in the corresponding cloud provider. It also supports modules, which are reusable pieces of infrastructure that can be shared across different projects, teams, and organizations.

State Management

Ansible does not keep a distinct state file. Rather, it utilizes the current state of target nodes while playbook execution is running. Although this makes management easier, there might be issues with monitoring and managing infrastructure variations over time.

Terraform keeps a state file that shows the current state of the infrastructure. It uses this information to understand which resources have been created, updated, or destroyed during each run. This information allows Terraform to make intelligent decisions regarding which resources should be created, updated, or destroyed during future runs.

Check out this blog to learn How to Manage Terraform State with Examples.

Learning Curve and Adoption

Ansible's simplicity and agentless architecture make it relatively easy to learn, particularly for users with experience in YAML and basic scripting. The learning curve may steepen when dealing with complex playbooks and orchestration scenarios.

Terraform's learning curve can be steeper due to its declarative language and the need to understand infrastructure concepts like state management and provider configurations. However, Terraform's comprehensive documentation and active community support help mitigate these challenges.

Community and Support

Ansible benefits from a large and active community of users, contributors, and maintainers. The Ansible Galaxy repository hosts thousands of reusable roles and playbooks contributed by the community, making it easy to find and share automation solutions.

Terraform has a vibrant community that actively contributes modules, plugins, and best practices. HashiCorp provides commercial support for Terraform through its enterprise offerings, along with extensive documentation and training resources.

Choosing the Right Tool

Selecting the right tool for infrastructure automation depends on various factors, including your organization's requirements, existing infrastructure, team expertise, and long-term goals. Here are the considerations to help you make an informed decision:

Infrastructure Complexity: If your environment includes diverse infrastructure components, such as servers, networking equipment, and cloud resources, Ansible's versatility and simplicity may be advantageous.

Cloud-native Environments: Terraform's IaC approach and provider ecosystem offer better integration and management capabilities for organizations heavily invested in cloud computing and containerization.

Team Skills and Preferences: Consider your team's existing skills and familiarity with programming languages, configuration management tools, and cloud platforms. To minimize learning curves, choose a tool that aligns with your team's expertise and preferences.

Automation Goals: Define your automation objectives, such as improving deployment speed, enhancing infrastructure reliability, or optimizing resource utilization. Evaluate how each tool addresses your specific requirements and fits into your workflows.

Integration Requirements: Assess the need to integrate automation workflows with existing tools, processes, and third-party services. Look for tools that offer robust integration capabilities and support industry standards for seamless interoperability.

Scalability and Maintainability: Consider each tool's scalability and maintainability, including support for version control and collaboration features. Choose a tool that can scale with your organization's growth and evolving infrastructure needs.

Conclusion

Both Ansible and Terraform are powerful utilities for infrastructure automation. Ansible stands out in configuration management, application deployment, and general-purpose automation. Terraform, on the other hand, is particularly good in infrastructure provisioning using the IaC methodology.

By explaining the anatomy of Ansible and Terraform and addressing their strengths and flaws, your skilled team can make the right decision for your success in DevOps and cloud computing.

If you are looking to polish your Terraform skills in a real-world environment? Enroll in our Terraform Basics Training Course, which covers all of Terraform fundamentals.

If you want to master Ansible, check out these KodeKloud courses:

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