Include configmap with non-managed helm chart - kubernetes

Question

I was wondering if it is possible to include a configmap with its own values.yml file with a helm chart repository that I am not managing locally. This way, I can uninstall the resource with the name of the chart.
Example:
I am using New Relics Helm chart repository and installing the helm charts using their repo name. I want to include a configmap used for infrastructure settings with the same helm deployment without having to use a kubectl apply to add it independently.
I also want to avoid having to manage the repo locally as I am pinning the version and other values separately from the help upgrade install set triggers.

Answer 1

What you could do is use Kustomize. Let me show you with an example that I use for my Prometheus installation.
I'm using the kube-prometheus-stack helm chart, but add some more custom resources like a SecretProviderClass.
kustomization.yaml:
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
helmCharts:
- name: kube-prometheus-stack
repo: https://prometheus-community.github.io/helm-charts
version: 39.11.0
releaseName: prometheus
namespace: prometheus
valuesFile: values.yaml
includeCRDs: true
resources:
- secretproviderclass.yaml
I can then build the Kustomize yaml by running kustomize build . --enable-helm from within the same folder as where my kustomization.yaml file is.
I use this with my gitops setup, but you can use this standalone as well.
My folder structure would look something like this:
.
├── kustomization.yaml
├── secretproviderclass.yaml
└── values.yaml

Answer 2

Using only Helm without any 3rd party tools like kustomize there are two solutions:
Depend on the configurability of the Chart you are using as described by #Akshay in the other answer
Declare the Chart you are looking to add a ConfigMap to as a dependency
You can manage the Chart dependencies in the Chart.yaml file:
# Chart.yaml
dependencies:
- name: nginx
version: "1.2.3"
repository: "https://example.com/charts"
With the dependency in place, you can add your own resource files (e.g., the ConfigMap) to the chart. During Helm install, all dependencies and your custom files will be merged into a single Helm deployment.
my-nginx-chart/:
values.yaml # defines all values including the dependencies
Chart.yaml # declares the dependencies
templates/ # custom resources to be added on top of the dependencies
configmap.yaml # the configmap you want to add
To configure values for a dependency, you need to prefix the parameters in your values.yaml:
my-configmap-value: Hello World
nginx: #<- refers to "nginx" dependency
image: ...