admin:iac [~wiki]

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====== Infrastructure as Code ======
Infrastructure as Code (IaC) is the practice of defining, provisioning, and managing infrastructure using machine-readable configuration files rather than manual setups. Tools like Terraform, Ansible, and Puppet enable teams to automate deployments, enforce consistency, and eliminate undocumented configuration drift.

===== Why IaC Matters =====
Without IaC, infrastructure becomes prone to silent configuration changes, manual fixes, and inconsistencies between environments. Using IaC ensures:

  * **Reproducibility** – Environments can be recreated identically.
  * **Transparency** – All changes are logged and reviewed through version control.
  * **Safety** – Automated checks reduce human error during large-scale changes.
  * **Collaboration** – Multiple engineers can understand, review, and improve infrastructure.

===== Key Principles =====
  * **Declarative Configuration** – Define the desired state, not the steps.
    * a list of imperative tasks should be idempotent, see below
  * **Idempotency** – Applying the same configuration yields the same outcome every time.
  * **Version Control** – Every change is reviewed, traceable, and reversible.
  * **Automation** – Tasks such as provisioning, scaling, and patching run automatically.

===== Benefits =====
  * Reduced reliance on "tribal knowledge."
  * Faster onboarding for new team members.
  * Simple recovery from failures – rebuild instead of repair.
  * Predictable, testable infrastructure rollouts.
  * Enables DevOps practices like CI/CD and ephemeral environments.

===== Common IaC Tools =====
  * **Terraform** – Multi-cloud provisioning at scale.
  * **Ansible** – Configuration management and automation. Imperative approach.
  * **Puppet** – Policy-based infrastructure management. Declarative Approach.
  * **Kubernetes Manifests / Helm Charts** – Declarative container orchestration.

===== Common Pitfalls =====
  * **Drift Between Environments** – Occurs when manual changes circumvent IaC.
  * **Poor Documentation** – IaC is code, and code needs clear documentation.
  * **Lack of Testing** – Misconfigurations can break entire systems.
  * **Overcomplication** – Not everything must be automated at once.

===== Best Practices =====
  * Commit all configuration to Git.
  * Use code reviews for infrastructure changes.
  * Test changes in staging environments before production.
  * Avoid manual changes; enforce policy-as-code where possible.
  * Regularly audit for drift.

===== See Also =====
  * [[:admin:runbooks|Ops Runbooks]]
  * [[:admin:hero|Hero Sysadmin]]
  * [[:dev:hero|Hero Developer]]