Jon Chery
d1aa5daf2b
---ci--- project: atelier phase: 5 milestone: v0.2 status: complete requirements: covered: [ATELIER-36, ATELIER-37, ATELIER-38, ATELIER-39, ATELIER-40, ATELIER-41, ATELIER-42, ATELIER-43, ATELIER-44, ATELIER-45, ATELIER-46, ATELIER-47, ATELIER-48, ATELIER-49, ATELIER-50, ATELIER-51, ATELIER-52, ATELIER-53, ATELIER-54, ATELIER-55, ATELIER-56, ATELIER-57, ATELIER-58, ATELIER-59] partial: [] ---/ci---
2.1 KiB
Infrastructure as Code — First Principles
1. The Principles
P1. Declarative Intent
Describe the desired state, not the steps to reach it. The tool reconciles current → desired. Imperative scripts describe how; declarative config describes what.
P2. Idempotence
Applying the same configuration twice yields the same result. A
second apply with no changes is a no-op, not an error. Idempotence
is what makes plan trustworthy.
P3. State is Truth
The state file is the authoritative record of what the tool believes exists. Drift between state and reality is a bug to be reconciled, not tolerated. Lose state, lose the ability to reason about infrastructure.
P4. Plan Before Apply
Preview every change before mutating real infrastructure. plan is
the contract review; apply is the signature. No apply without a
read plan. The plan is the rollback rehearsal.
P5. Version Everything
Configuration, state, providers, and modules are all versioned and
reproducible. A commit pins a complete, rebuildable world. Pin
providers; pin module sources; never latest.
P6. Modules Compose
Encapsulate repeatable patterns as versioned modules. Compose modules; do not copy them. A module is the unit of reuse, review, and versioning — the IaC expression of composition.
P7. Least Privilege Providers
Provider credentials are scoped to the minimum needed for the declared resources. No account-wide admin keys in CI. One credential per environment, per boundary.
P8. Remote State with Locking
State is stored remotely with locking. Local state is for a single
developer on a throwaway sandbox. Concurrent apply without a lock
is data corruption waiting to happen.
P9. Drift is Recoverable
plan detects drift; apply reconciles it. Manual mutation of
managed infrastructure is an incident, not a shortcut. Drift is
expected; unreconciled drift is the bug.
P10. Secrets Never in Code
Secrets come from providers, external secret stores, or environment variables — never hardcoded in HCL, never committed to the repo, never written to state in plaintext. State is a secret-bearing artifact; treat it accordingly.