Infrastructure as Code: principles, tools, and best practices

Infrastructure as Code transforms infrastructure management — versioning, testing, and code review for servers and networks. An overview of tools and how to get started.

From snowflake servers to reproducible infrastructure¶

A “snowflake server” is one that nobody can reproduce — it accumulated months of manual changes and its loss would be catastrophic. Infrastructure as Code (IaC) eliminates snowflakes.

IaC principles:

• Infrastructure is defined in code (text files)
• Versioned in git like application code
• Testable and reviewable
• Reproducible — creating a new environment is a push of a button

Configuration management: Ansible vs Puppet vs Chef¶

Three dominant tools for server configuration:

Ansible — agentless, YAML playbooks, SSH-based:

- hosts: webservers
  tasks:
    - name: Install nginx
      apt: name=nginx state=present
    - name: Start nginx
      service: name=nginx state=started enabled=yes

Puppet — agent-based, declarative DSL, strong in the enterprise.

Chef — agent-based, Ruby DSL, flexible but complex.

Recommendation: Ansible for new projects due to its simplicity and agentless architecture.

Immutable infrastructure¶

A more progressive approach: instead of updating servers, you replace them with new ones.

• Build a server image (AMI, Docker image) in the CI pipeline
• Deploy = swap instances for new ones with the new image
• No SSH into production, no configuration drift
• Rollback = deploying the previous image

Packer from HashiCorp automates building machine images. Combined with Terraform for provisioning, it forms a complete IaC stack.

Testing infrastructure¶

Infrastructure code needs tests just like application code:

• Linting — ansible-lint, puppet-lint validate syntax and best practices
• Unit tests — ChefSpec, rspec-puppet test individual resources
• Integration tests — Test Kitchen, Molecule run the configuration in a VM and verify the result
• Compliance — InSpec defines security and compliance requirements as code

Conclusion: code is law¶

Infrastructure as Code is a fundamental building block of modern IT. It eliminates manual errors, ensures consistency, and enables rapid scaling. If you are still managing servers manually, it is time to change. Start with Ansible and version everything in git.