How do I inject preview specific configuration?

Preview Environments are similar to other environments like Staging and Production only instead of storing the environments in a separate git repository the preview environment is defined inside each applications charts/preview folder.

So to inject any custom configuration into your Preview environment you can modify the charts/preview/values.yaml file in your applications git repository to override any helm template parameters defined in your chart (in the charts/myapp folder).

You may need to modify your helm charts to add extra helm configuration if the configuration you wish to configure is not easily changed via the values.yaml file.

For additional information, see also how to inject environment specific configuration into environments.