Create HelmRepository and HelmRelease using helm template approach for Flux

Both the helm-repository.yaml and helm-release.yaml files share common patterns and values that can be templated to reduce repetition and make it easier to deploy multiple applications with Flux and Helm. By creating a reusable template, you can parameterize fields like the chart name, version, namespace, and repository URL, then generate these files for different applications (e.g., podinfo, crossplane, etc.) with minimal effort.

Since we have been working with Flux and Helm on kubernetes, let's explore this approach.

Common Values to Template

From my previous examples (podinfo, crossplane), the common elements include:

• HelmRepository:

  • metadata.name: The repository name (e.g., podinfo, crossplane).
  • spec.url: The chart repository URL.
  • spec.interval: Sync interval (e.g., 1h).
  • metadata.namespace: Typically flux-system.

• HelmRelease:

  • metadata.name: Matches the app name.
  • spec.chart.spec.chart: The chart name.
  • spec.chart.spec.version: The chart version or range.
  • spec.chart.spec.sourceRef.name: References the HelmRepository name.
  • spec.interval: Reconciliation interval (e.g., 5m).
  • metadata.namespace and spec.targetNamespace: The target namespace for deployment.
  • spec.values: Custom values (app-specific).

Helm Chart Template

Since we are already using Helm with Flux, we can create a Helm chart to template these Flux resources. This leverages Helm’s templating engine.

1. Create a Helm Chart:

helm create flux-template
rm -rf flux-template/templates/*

2. Create appName-values.yaml:

Create crossplane-values.yaml file:

mkdir flux-template/crossplane
vim flux-template/crossplane/crossplane-values.yaml

Take a look at template-values.yaml file in flux-templates folder, you will find the required variables and the customValues in case you want to add a customValues map.

Add the common values:

appName: crossplane
repoUrl: https://charts.crossplane.io/stable
chartVersion: "1.19.0"
namespace: crossplane-system
customValues:
  args:
    - "--debug"
  resources:
    requests:
      cpu: "100m"
      memory: "128Mi"
    limits:
      cpu: "200m"
      memory: "256Mi"

3. Add helm-repository.yaml Template:

Create flux-template/templates/helm-repository.yaml:

apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: HelmRepository
metadata:
  name: {{ .Values.appName }}
  namespace: flux-system
spec:
  interval: 1h
  url: {{ .Values.repoUrl }}

4. Add helm-release.yaml Template:

Create flux-template/templates/helm-release.yaml:

# This is a HelmRelease CRD that Flux will use to deploy {{ .Values.appName }}.
apiVersion: helm.toolkit.fluxcd.io/v2
kind: HelmRelease
metadata:
  name: {{ .Values.appName }}
  namespace: {{ .Values.namespace }}
spec:
  interval: {{ .Values.interval }}
  chart:
    spec:
      chart: {{ .Values.appName }}
      version: {{ quote .Values.chartVersion }}
      sourceRef:
        kind: HelmRepository
        name: {{ .Values.appName }}
        namespace: flux-system
  releaseName: {{ .Values.appName }}
  targetNamespace: {{ .Values.namespace }}
  install:
    createNamespace: true
  {{- if .Values.customValues }}
  # Optional customizations
  values:
    {{- range $key, $value := .Values.customValues }}
    {{ $key }}:
      {{- if kindIs "slice" $value }}
      {{- range $item := $value }}
      - {{ quote $item }}
      {{- end }}
      {{- else }}
      {{- toYaml $value | trim | nindent 6 }}
      {{- end }}
    {{- end }}
  {{- end }}

5. Generate Files:

For Crossplane:

helm template flux-template -f crossplane/crossplane-values.yaml --output-dir flux-template/crossplane/

6. Commit to Git:

git add crossplane/flux-template/templates
git commit -m "Add templated deployments"
git push

Pros and Cons

Pros: Leverages Helm’s powerful templating, reusable across projects.

Cons: Requires Helm installed locally, slightly more setup.

Happy templating 😊