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Infrastructure as Code (IaC)

🧠 Objectives

By the end of this session, students will:

  • Understand what Infrastructure as Code (IaC) means.
  • Differentiate between imperative and declarative approaches.
  • Explore real-world benefits of IaC.
  • Learn about popular IaC tools like Terraform, Ansible, Puppet, and Chef.

📖 What is Infrastructure as Code?

Infrastructure as Code (IaC) is the practice of managing and provisioning infrastructure (servers, networks, storage, databases) using machine-readable configuration files instead of manual processes or GUIs.

Think of IaC as "treating infrastructure like software":

  • Code defines what your servers should look like.
  • Version control stores the configuration.
  • Automation tools build the infrastructure consistently.

⚖️ Two Approaches in IaC

  1. Imperative (Procedural)

    • Tells the system how to reach the desired state (step by step).
    • Example: Shell scripts, Puppet in procedural mode.

  2. Declarative (Desired State)

    • Tells the system what the final state should look like.
    • Example: Terraform, Ansible.

Analogy

Imperative = “Bake a cake step by step.”

Declarative = “I want a chocolate cake.” (The system figures out steps).

🎯 Benefits of IaC

  • Consistency → No configuration drift.
  • Speed → Faster provisioning and scaling.
  • Versioning → Track infra changes like source code.
  • Collaboration → Teams can peer-review infra just like code.
  • Scalability → Reuse configs across dev, test, prod.
  • Terraform (HashiCorp) → Declarative, cloud-agnostic.
  • Ansible (Red Hat) → Simple YAML playbooks, agentless.
  • Puppet → Used in enterprise, can be both declarative/imperative.
  • Chef → Ruby DSL, more developer-centric.

📊 IaC Lifecycle

flowchart LR
    A[Write Configuration Code] --> B[Plan Changes]
    B --> C[Apply Configuration]
    C --> D[Provision Infrastructure]
    D --> E[Manage & Update]
    E --> F[Destroy when no longer needed]

🌍 Real-World Examples

  • Terraform on AWS: Spin up EC2, VPCs, security groups with one command.
  • Ansible Playbooks: Configure web servers with consistent packages.
  • Hybrid Infra: Use Terraform to create infra and Ansible to configure apps.