Helm in Practice

Default Helm Labels

In our previous example, we ran the following command to verify the installation:

kubectl get all -l app.kubernetes.io/instance=my-wordpress

The label app.kubernetes.io/instance is one of the default labels that Helm adds to all the Kubernetes resources it creates. This label helps identify which resources belong to a specific Helm release.

There are other default labels that are automatically added by Helm as well:

• app.kubernetes.io/name: The name of the chart (e.g., wordpress).
• app.kubernetes.io/version: The version of the application (e.g., 5.8.1).
• app.kubernetes.io/managed-by: The tool managing the deployment (e.g., Helm).
• app.kubernetes.io/component: The component within the application (e.g., web, database, frontend, backend, etc., depending on the chart).
• app.kubernetes.io/part-of: The name of the larger application this component is part of (e.g., my-application).
• helm.sh/chart: The name and version of the chart (e.g., wordpress-10.1.5).

These labels are created based on the information provided in the Chart.yaml file and the release name specified during installation. The following table summarizes what's created and how:

Below is a practical explanation of every template reference that appears in the table:

{{ template "name" . }}

This calls a named template defined in _helpers.tpl files. Many charts include a template like this:

{{- define "name" -}}
{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" -}}
{{- end -}}