Kustomize

Kustomize is a Kubernetes native configuration management tool that introduces a template-free way to customize application configuration, simplifying the use of off-the-shelf applications. Now built directly into kubectl as the apply dash k command, Kustomize has become the standard approach for managing Kubernetes manifests without the complexity of templating engines like Helm. The tool traverses Kubernetes manifests to add, remove, or update configuration options without forking, maintaining a purely declarative approach to configuration customization. Every artifact that Kustomize uses is plain YAML that can be validated and processed as standard Kubernetes resources, making configurations transparent and debuggable. Kustomize manages an arbitrary number of distinctly customized Kubernetes configurations through a base-and-overlays model, where a common base configuration is shared across multiple environments (development, staging, production) with environment-specific patches layered on top. This fork, modify, and rebase workflow enables teams to maintain shared application manifests while customizing deployment-specific settings such as replica counts, resource limits, environment variables, and namespace assignments. Available both as a standalone binary for integration into other services and as a native kubectl feature, Kustomize is maintained as part of the Kubernetes CLI Special Interest Group and is widely adopted across the Kubernetes ecosystem as the recommended configuration management approach.