Infrastructure as Code (IaC) is a methodology for managing and provisioning cloud infrastructure resources using code and automation. It can be used not only on resources that are part of your cloud service like S3 buckets, Lambda, Security Groups, but increasingly on SaaS applications like Okta, New Relic, DataDog and more (often referred to as Everything-as-code).

While IaC itself doesn't inherently make your cloud infrastructure immutable, it provides the tools and practices to help you achieve immutability as a desired state. Here's how IaC contributes to making your cloud infrastructure more immutable:

1. Declarative Definition: With IaC, you define your infrastructure resources, configurations, and dependencies in code using a declarative syntax. This code describes the desired state of your infrastructure rather than the step-by-step procedures to create it. This means you specify what you want your infrastructure to look like, not how to create it.

2. Version Control: IaC code is typically stored in version control systems like Git. This allows you to track changes over time, compare different versions, and revert to previous states if necessary. Immutability is partially achieved through version control because you can always recreate a previous version of your infrastructure.

3. Automated Provisioning: IaC tools (e.g., Terraform, AWS CloudFormation, Ansible) automate the process of creating, updating, and deleting infrastructure resources based on your code. When changes are required, you modify the code, and the IaC tool applies those changes to the infrastructure. This automation ensures consistency and minimizes manual intervention, reducing the risk of configuration drift.

4. Reproducibility: Immutability relies on the ability to recreate infrastructure from scratch. With IaC, you can create identical copies of your infrastructure by running the same code. This ensures that your infrastructure remains consistent and reproducible, as opposed to manual configuration efforts (aka ClickOps), which can lead to variations over time.

5. Scalability and Flexibility: IaC allows you to easily scale your infrastructure up or down by modifying code parameters. You can add or remove resources, change configurations, or even create entirely new environments using the same codebase. This flexibility supports immutable patterns by facilitating the creation of new instances instead of modifying existing ones.

6. Testing and Validation: IaC enables automated testing of your infrastructure code, ensuring that it meets your desired specifications before deployment. This helps catch errors and misconfigurations early.

7. Immutable Deployments: While IaC alone doesn't make your infrastructure immutable, it's often used in conjunction with immutable deployment practices. In an immutable deployment, you create a new instance of your infrastructure whenever changes are needed, rather than modifying existing instances. IaC simplifies this process by defining the new desired state and automating the creation of the new infrastructure, making it easier to follow immutable deployment practices.

8. Rollback and Recovery: In cases of issues or security vulnerabilities, you can quickly roll back to a known good state by reverting to a previous version of your IaC code. This ensures that you have a clear and consistent path for recovery in case of problems.

In summary, while IaC itself doesn't make your cloud infrastructure immutable, it provides the necessary tools, practices, and automation to help you maintain and enforce immutability principles. By defining your infrastructure as code, you can more easily create, manage, and reproduce infrastructure in a consistent and immutable manner, reducing the risk of configuration drift and ensuring greater reliability and security.

Wondering which IaC framework to use? There are several and Firefly supports the ones most used. Check out our other blogs on Pulumi vs Terraform considerations and Navigating Terraform vs OpenTofu.