Extending the Chart¶

In some cases, you will want to deploy your custom templates (e.g. maintenance CronJobs you want to add) together with the Airflow chart installation. However, sometimes those templates are not directly related to the Airflow chart, thus should not be added to the chart.

Instead, you can easily extend the chart and create a custom chart with your custom templates that depends on the Airflow chart. When you’ll install your custom chart, the Airflow chart will also be installed.

You can extend the official Airflow chart by applying the following steps.

Create your custom Chart¶

First, you will need to create you own chart directory. You can do it by running the following command:

helm create my-custom-chart

This command will create a directory called my-custom-chart with the following structure:

my-custom-chart/
├── .helmignore
├── Chart.yaml
├── values.yaml
├── charts/
└── templates/
    └── tests/

Add Airflow chart as dependency¶

Second, you will need to add the Airflow chart as dependency to your chart. This will give you the ability to add your custom templates without the need to modify the Airflow chart itself. In order to add the Airflow chart as a dependency (often called subcharts) to your chart, add the following lines to your Chart.yaml file:

dependencies:
  - name: airflow
    version: 1.11.0
    repository: https://airflow.apache.org

Note

Make sure you have already added the Airflow repo locally by running: helm repo add apache-airflow https://airflow.apache.org.

Tip

You can also use the name of the repo instead of the URL by replacing https://airflow.apache.org with "@apache-airflow".

Adding the Airflow chart as a dependency means that it will be deployed together with your custom chart. You can disable the installation of Airflow by adding the condition field to the dependencies section. For example:

dependencies:
  - name: airflow
    version: 1.11.0
    repository: https://airflow.apache.org
    condition: airflow.enabled

This will check if the value of airflow.enabled inside your values.yaml is true. If it is, the Airflow chart will be deployed together with your custom chart. Otherwise, only your templates will be deployed.

Download the Airflow Chart¶

Third, after you have specified the Airflow chart inside the dependencies section in Chart.yaml file, you can download the Airflow chart by running the following command:

helm dependency build

Note

Make sure you are inside the directory which contains the Chart.yaml file.

The chart will be downloaded and saved inside the charts/ directory.

Overriding default values¶

When you add a chart as a subchart to your chart, you have the ability to override the default values of the subchart in your values.yaml. This is useful when your chart needs a specific configuration for your custom chart. E.g. if you want that the Airflow chart be installed with the KubernetesExecutor, you can do it by adding the following section to your values.yaml:

airflow:
  executor: KubernetesExecutor

You can override as many values as you like.