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---
55 lines
2.1 KiB
Markdown
55 lines
2.1 KiB
Markdown
# 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. |