Kubernetes Patterns

Advanced Kubernetes Patterns

1. Skill Context

Focus: Sidecar, Ambassador, Operator patterns, Admission Webhooks, Node affinity, and workload resiliency. Triggers: k8s patterns, kubernetes operator, mutating webhook, pod disruption budget, advanced scheduling

2. Advanced Kubernetes Architecture

The agent must design resilient, self-healing, and highly available Kubernetes deployments.

Structural Patterns

• Sidecar Pattern: Augmenting the main container (e.g., logging agent, OTel collector, proxy).
• Ambassador Pattern: A sidecar that proxies network connections to the outside world, handling retries, circuit breaking, and mTLS (e.g., Envoy).
• Operator Pattern: Extending the K8s API using Custom Resource Definitions (CRDs) and writing custom controllers (in Go/Rust) to manage complex stateful applications (e.g., running PostgreSQL clusters).

Resiliency & Scheduling

• Pod Disruption Budgets (PDBs): Preventing cluster administrators or autoscalers from draining nodes if it would drop a deployment below a minimum available threshold (quorum).
• Taints, Tolerations, and Affinity:
  • Taints: Repelling pods from specific nodes (e.g., GPU nodes or dedicated tenant nodes).
  • Affinity: Attracting pods to specific nodes or ensuring pods from the same deployment do not land on the same physical underlying host (podAntiAffinity with topologyKey: kubernetes.io/hostname).

Security & Governance

• Admission Webhooks: Using ValidatingAdmissionWebhook to reject deployments that violate policy (e.g., running as root) or MutatingAdmissionWebhook to automatically inject sidecars or environment variables.

3. Output Format

• Provide deeply commented Kubernetes YAML manifests.
• Diagram the communication flow between custom controllers and the API server.
• Focus on zero-downtime deployments and graceful shutdown (e.g., preStop hooks and terminationGracePeriodSeconds).