You can specify a custom nginx.conf file by creating a ConfigMap or Secret and mounting it inside your container that contains an nginx_kong.lua template.
Use the following fields in values.yaml:
- 
deployment.userDefinedVolumes: this field takes an array of objects that get appended as-is to the existingspec.template.spec.volumesarray in the Kong Gateway deployment resource.
- 
deployment.userDefinedVolumeMounts: this field is appended as-is to the existingspec.template.spec.containers[].volumeMountsandspec.template.spec.initContainers[].volumeMountsarrays.
The volumes to mount are provided under the deployment key in your Helm values.yaml file. The structure of the configuration matches the Kubernetes ConfigMapVolumeSource or SecretVolumeSource structure.