AWS CloudFormation vs Ansible: What are the differences?

AWS CloudFormation and Ansible are two popular tools used for infrastructure automation. Let's explore the key differences between them.

1. Orchestration vs Configuration Management: AWS CloudFormation primarily focuses on orchestrating and managing resources in the AWS ecosystem. It provides a declarative language, using which you can define the desired state of your infrastructure and let CloudFormation handle the provisioning and management of resources. On the other hand, Ansible is a configuration management tool that focuses on configuring and managing software and systems. It uses a procedural language to define the steps required for achieving a desired state.

2. Scope: AWS CloudFormation is tailored specifically for managing AWS resources. It provides a wide range of resource types, such as EC2 instances, S3 buckets, RDS databases, etc., that can be provisioned, updated, or deleted using CloudFormation templates. In contrast, Ansible is agnostic to the cloud provider and can be used to manage resources on various platforms, including public clouds, private clouds, and even physical servers.

3. Learning Curve and Complexity: AWS CloudFormation involves a steeper learning curve as it requires knowledge of the CloudFormation syntax and understanding of various AWS resource types and their configuration. Mastering CloudFormation templates and best practices can take time. On the other hand, Ansible has an easier learning curve, especially for those familiar with YAML syntax. Ansible playbooks are generally easier to understand and write, making it more accessible to beginners.

4. Statefulness: CloudFormation has a concept of stacks, which represent the state of your infrastructure. Each time you update a CloudFormation stack, it compares the current state with the desired state declared in the template and applies the necessary changes. In contrast, Ansible does not have built-in state tracking. Each time you run an Ansible playbook, it executes all the defined tasks, even if they have been executed before. This can lead to unnecessary overhead, especially for large playbooks.

5. Extensibility: Ansible offers a rich ecosystem of community-supported modules that allow you to extend its functionality and integrate with various tools and platforms. These modules can be easily shared, customized, and reused. CloudFormation, on the other hand, has limited extensibility options. It relies on AWS resource types and CloudFormation-specific constructs for provisioning and management tasks.

6. Deployment and Execution: AWS CloudFormation templates are deployed and executed through the AWS Management Console, AWS CLI, or SDKs. It seamlessly integrates with other AWS services, such as AWS CodePipeline for continuous deployment. On the other hand, Ansible playbooks are executed through the Ansible command-line tool or Ansible Tower. Ansible supports various deployment methods, including ad-hoc execution, rolling updates, and integration with CI/CD pipelines.

In summary, AWS CloudFormation focuses on orchestrating and managing AWS resources using a declarative approach, whereas Ansible is a configuration management tool that can be used to manage resources on various platforms. CloudFormation has a steeper learning curve, is AWS-centric, and has built-in state tracking. Ansible, on the other hand, has an easier learning curve, is more extensible, and lacks built-in state tracking.