Free PDF — Engineering Reference

Kubernetes Operator Patterns

Building CRDs That Don't Wake You at 3AM

Every Kubernetes operator pattern in one reference. CRD design, controller architecture, reconciliation loops, finalizers, webhooks, status fields, leader election. Build operators that survive production.

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Reconciliation Loops The level-triggered, idempotent, requeue-aware pattern. Why most first-attempt operators corrupt state.
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CRD Design Rules Spec vs status, validation, versioning, schemas. The decisions that haunt you 18 months in.
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Webhooks & Admission Mutating + validating webhooks, conversion webhooks, failure policies. When to use, when to avoid.
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Production Operations Leader election, work queues, rate limiting, metrics, finalizers. The infrastructure beneath the logic.

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What's Inside

Design

  • CRD spec/status split — what goes where
  • Schema validation with OpenAPI
  • Versioning and conversion webhooks
  • Naming and grouping conventions

Controller

  • Level-triggered reconciliation pattern
  • Idempotency and side-effect isolation
  • Watching owned + external resources
  • Requeue, backoff, RateLimitingInterface

Webhooks

  • Mutating webhook patterns + pitfalls
  • Validating webhook design
  • Conversion webhooks for v1alpha1 → v1
  • Failure policies and webhook availability

Production

  • Leader election with lease objects
  • Finalizers and proper cleanup
  • Metrics, structured logging, traces
  • Upgrade strategy and operator versioning