kustomize - bobbae/gcp GitHub Wiki
Kustomize introduces a template-free way to customize application configuration built into kubectl as apply -k.
https://kubectl.docs.kubernetes.io/guides/introduction/kustomize/
Kustomize offers a plugin framework allowing people to write their own resource generators and transformers.
https://kubectl.docs.kubernetes.io/guides/extending_kustomize/
Helm is the package manager for Kubernetes.
https://harness.io/blog/helm-vs-kustomize/
https://testingclouds.wordpress.com/2018/07/20/844/