One little-know feature of Helm charts is the ability to share chart definitions among all templates in a chart, including any of the subchart templates.

The common chart is a chart that defines commonly used Chart primitives that can be used in all of your charts.

See the Documentation for complete API documentation and examples.

The Common chart is served out of a GitHub Pages Repository. To register the repository, do this:

$ helm repo add common https://technosophos.github.io/common-chart/

Create a new chart:

$ helm create mychart

Include the common chart as a subchart:

$ cd mychart/charts
$ helm fetch common

Use the common.* definitions in your code. For example, we could add this to a chart's templates/service.yaml.

apiVersion: v1
kind: Service
metadata:
  name: {{ include "common.fullname" . }} # <--- THE IMPORTANT PART
  labels:
{{ include "common.labels.standard" . | indent 4 }} # <--- Ooo... look.
spec:
  type: {{ .Values.service.type }}
  ports:
  # common.port handles formatting of port numbers.
  - port: {{ include "common.port" .Values.service.externalPort }}
    targetPort: {{ include "common.port" .Values.service.internalPort }}
    protocol: TCP
    name: {{ .Values.service.name }}
  selector:
    app: {{ template "common.fullname" . }} # Another way to accomplish this

Above, we use three of the common tools:

• common.fullname to generate a full name for our service
• common.labels.standard to generate the standard labels for us
• common.port to format port numbers for us

The above will produce something like this:

metadata:
  name: release-name-mychart
  labels:
    app: "release-name-mychart"
    chart: "mychart-0.1.0"
    heritage: "Tiller"
    release: RELEASE-NAME
spec:
  type: ClusterIP
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
    name: nginx
  selector:
    app: release-name-mychart

The Common chart has many other utilities.

If you are developing on this project, you can use make build to build the charts. Note that the makefile requires signing your chart.