Jon Chery
b997bd63b1
---ci--- project: atelier phase: 1 milestone: v0.2 status: complete requirements: covered: [ATELIER-36, ATELIER-37, ATELIER-38, ATELIER-39, ATELIER-40] partial: [] ---/ci---
55 lines
2.1 KiB
Markdown
55 lines
2.1 KiB
Markdown
# Infrastructure as Code — First Principles
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## 1. The Principles
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### P1. Declarative Intent
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Describe the desired state, not the steps to reach it. The tool
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reconciles current → desired. Imperative scripts describe how;
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declarative config describes what.
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### P2. Idempotence
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Applying the same configuration twice yields the same result. A
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second `apply` with no changes is a no-op, not an error. Idempotence
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is what makes `plan` trustworthy.
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### P3. State is Truth
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The state file is the authoritative record of what the tool believes
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exists. Drift between state and reality is a bug to be reconciled,
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not tolerated. Lose state, lose the ability to reason about
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infrastructure.
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### P4. Plan Before Apply
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Preview every change before mutating real infrastructure. `plan` is
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the contract review; `apply` is the signature. No `apply` without a
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read `plan`. The plan is the rollback rehearsal.
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### P5. Version Everything
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Configuration, state, providers, and modules are all versioned and
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reproducible. A commit pins a complete, rebuildable world. Pin
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providers; pin module sources; never `latest`.
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### P6. Modules Compose
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Encapsulate repeatable patterns as versioned modules. Compose
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modules; do not copy them. A module is the unit of reuse, review,
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and versioning — the IaC expression of composition.
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### P7. Least Privilege Providers
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Provider credentials are scoped to the minimum needed for the
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declared resources. No account-wide admin keys in CI. One credential
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per environment, per boundary.
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### P8. Remote State with Locking
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State is stored remotely with locking. Local state is for a single
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developer on a throwaway sandbox. Concurrent `apply` without a lock
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is data corruption waiting to happen.
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### P9. Drift is Recoverable
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`plan` detects drift; `apply` reconciles it. Manual mutation of
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managed infrastructure is an incident, not a shortcut. Drift is
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expected; unreconciled drift is the bug.
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### P10. Secrets Never in Code
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Secrets come from providers, external secret stores, or environment
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variables — never hardcoded in HCL, never committed to the repo,
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never written to state in plaintext. State is a secret-bearing
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artifact; treat it accordingly. |