Post rendering
When developing Helm charts, you should carefully consider each of the different values that need to be included in your chart. For example, if you know users may need to change the Service type within Service templates, you should expose a value to do so to keep your chart flexible. The same idea holds true for image names, resources, health checks, and other settings users would need to configure based on your use case.
Sometimes, however, users will still require additional flexibility that is not provided by a Helm chart. This is where post rendering comes into play. Post rendering is an advanced feature of Helm that allows users to perform further modifications to rendered chart templates when they install your chart. It is often seen as a last resort if they require modifications that your Helm chart does not allow.
Post rendering is applied by adding the --post-renderer flag to the install, upgrade, or template commands. Here is an example:
$ helm install...