Helm is the package manager for Kubernetes
Why is this technology on hold?
Helm helps you manage Kubernetes applications — Helm Charts help you define, install, and upgrade even the most complex Kubernetes application.
Charts are easy to create, version, share, and publish, which leads to a lot less copy-and-pasting.
It is part of the Cloud Native Computing Foundation.
Helm 3 brought major changes to the tool and its usage, and is currently not yet adopted by our teams, trials are ongoing.
Kustomize offers a template-free way to customize Kubernetes application configuration. It achieves that by combining plain Kubernetes resource files with some clever tools that ease managing things as labels, annotations, ConfigMaps or Secrets.
Purely declarative approach to configuration customization
Natively built into kubectl
Manage an arbitrary number of distinctly customized Kubernetes configurations
Available as a standalone binary for extension and integration into other services
Every artifact that kustomize uses is plain YAML and can be validated and processed as such
Kustomize encourages a fork/modify/rebase workflow
It is actually possible to apply configuration changes to an existing Helm chart, using Kustomize (see https://testingclouds.wordpress.com/2018/07/20/844/).