Advanced Kubernetes Configuration Management

Table of Contents

• Overview
• Configuration Goals
• Configuration Layers and Ownership
• GitOps as Source of Truth
• Helm vs Kustomize Strategy
• Secrets and Sensitive Configuration
• Drift Detection and Reconciliation
• Policy as Code and Admission Controls
• Promotion Across Environments
• Safe Rollout and Rollback
• Observability for Configuration Health
• Reference Layout
• Common Anti-Patterns
• Production Checklist
• Conclusion

Advanced Kubernetes Configuration Management

Overview

Most Kubernetes incidents are configuration problems, not scheduler bugs. Advanced configuration management focuses on consistency, auditability, and safe change promotion.

The objective is simple:

1. Every change is declared.
2. Every change is reviewed.
3. Every cluster converges to known good state.

Configuration Goals

1. Deterministic deploys across environments.
2. Fast rollback for bad config changes.
3. Clear ownership boundaries by team/app/platform.
4. Strong policy enforcement before and during admission.
5. Minimal manual kubectl operations in production.

Configuration Layers and Ownership

Use layered config with explicit owners:

1. Base application manifests:
   • Owned by service team.
2. Environment overlays (dev, staging, prod):
   • Shared between service and platform.
3. Cluster platform defaults (ingress class, quotas, policies):
   • Owned by platform team.

Keep shared defaults centralized, and app-specific overrides local to the app.

GitOps as Source of Truth

Core pattern:

1. Git repository stores desired state.
2. GitOps controller applies state continuously.
3. Drift is detected and reconciled.
4. Manual cluster edits are either blocked or reverted.

Benefits:

1. Complete audit trail.
2. Reproducible rollback by reverting commit.
3. Reduced configuration drift between clusters.

Helm vs Kustomize Strategy

Use one primary abstraction per repo to reduce complexity.

Pragmatic split:

1. Helm for reusable templated applications and packaged releases.
2. Kustomize for environment overlays and patch-based composition.

Avoid:

1. Deeply nesting Helm inside Kustomize inside custom scripts unless there is clear value.

Secrets and Sensitive Configuration

Separate sensitive and non-sensitive configuration.

1. ConfigMap for non-sensitive app settings.
2. Secret manager integration for credentials and keys.
3. Short-lived credentials over static secrets where possible.
4. Rotate secrets and coordinate rollout automatically.

Operational rule:

1. Never commit plaintext secrets to Git.

Drift Detection and Reconciliation

Drift sources:

1. Manual kubectl edit.
2. Out-of-band hotfixes.
3. Controller race conditions.

Controls:

1. Enable continuous reconciliation with alerting on drift.
2. Restrict production write access to GitOps controllers.
3. Record and review every reconcile conflict.

Policy as Code and Admission Controls

Enforce invariants at admission time:

1. Required labels/annotations.
2. Resource requests/limits.
3. Allowed image registries and signed images.
4. Prohibited privileged container settings.
5. Network policy requirements per namespace.

Use policy engines (for example, OPA Gatekeeper or Kyverno) and fail builds pre-merge when manifests violate policy.

Promotion Across Environments

Promotion model:

1. Build artifact once.
2. Promote the same digest through environments.
3. Change only environment configuration, not binary contents.

Recommended controls:

1. PR-based promotion with approvals.
2. Automated validation in each environment.
3. Freeze windows for high-risk periods.

Safe Rollout and Rollback

Configuration can break runtime behavior even when pods are healthy.

Mitigations:

1. Canary config rollout for high-risk changes.
2. Progressive traffic shifts with SLO checks.
3. Fast rollback via Git revert and forced reconcile.
4. Separate app-code rollback from config rollback runbooks.

Observability for Configuration Health

Track:

1. Config change failure rate.
2. Mean time to detect bad config.
3. Reconcile loop errors and lag.
4. Drift count by namespace/team.
5. Rollback frequency by change type.

Add dashboards that correlate config commits with error rates and latency changes.

Reference Layout

platform-config/
├── clusters/
│   ├── prod-us/
│   ├── prod-eu/
│   └── staging/
├── apps/
│   ├── catalog/
│   │   ├── base/
│   │   └── overlays/
│   │       ├── dev/
│   │       ├── staging/
│   │       └── prod/
│   └── checkout/
├── policies/
│   ├── required-labels/
│   ├── security-context/
│   └── image-signature/
└── README.md

Common Anti-Patterns

1. Manual prod edits with no Git backport.
2. Mixing secrets and plain config in one file.
3. Unbounded environment-specific forks of manifests.
4. No policy checks until after deployment.
5. Promoting unpinned image tags (for example, latest).

Production Checklist

1. GitOps controller is the only production writer.
2. Config and secrets are split with strict handling rules.
3. Admission policies enforce security and reliability baseline.
4. All promotions are digest-pinned and review-gated.
5. Drift and reconcile health are monitored continuously.
6. Rollback is tested and documented for both app and config changes.

Conclusion

Advanced Kubernetes configuration management is about control loops, not just YAML structure. When Git is authoritative, policies are enforced, and rollbacks are routine, configuration changes stop being a primary outage source.