Kustomize Kubernetes Patches

Kustomize is a tool for customizing Kubernetes manifests without a templating language. You define base manifests (deployment, service, configmap), then overlays that patch the base for different environments (dev, staging, prod). Patches are declarative YAML files—no templating language (like Helm templates). Kustomize uses two patching strategies: strategic merge patches (merge YAML structures) and JSON6902 patches (surgical changes at specific JSON paths). Combined with generators (auto-create ConfigMaps/Secrets), it's powerful for managing manifests across environments.