Input Type | Helm

This is a Python binding to helm template command for users with helm charts. This does not require the helm executable, and the templates are rendered without the Tiller server.

Unlike other input types, Helm input types support the following additional parameters under kapitan.compile:

parameters:
  kapitan:
    compile:
    - output_path: <output_path>
      input_type: helm
      input_paths:
        - <chart_path>
      helm_values:
        <object_with_values_to_override>
      helm_values_files:
        - <values_file_path>
      helm_path: <helm binary>
      helm_params:
        name: <chart_release_name>
        namespace: <substitutes_.Release.Namespace>
        output_file: <string>
        validate: true
        …

helm_values is an object containing values specified that will override the default values in the input chart. This has exactly the same effect as specifying --values custom_values.yml for helm template command where custom_values.yml structure mirrors that of helm_values.

helm_values_files is an array containing the paths to helm values files used as input for the chart. This has exactly the same effect as specifying --file my_custom_values.yml for the helm template command where my_custom_values.yml is a helm values file. If the same keys exist in helm_values and in multiple specified helm_values_files, the last indexed file in the helm_values_files will take precedence followed by the preceding helm_values_files and at the bottom the helm_values defined in teh compile block. There is an example in the tests. The monitoring-dev(kapitan/tests/test_resources/inventory/targets/monitoring-dev.yml) and monitoring-prd(kapitan/tests/test_resources/inventory/targets/monitoring-prd.yml) targets both use the monitoring(tests/test_resources/inventory/classes/component/monitoring.yml) component. This component has helm chart input and takes a common.yml helm_values file which is "shared" by any target that uses the component and it also takes a dynamically defined file based on a kapitan variable defined in the target.

helm_path can be use to provide the helm binary name or path. helm_path defaults to the value of KAPITAN_HELM_PATH env var if it is set, else it defaults to helm

helm_params correspond to the flags for helm template. Most flags that helm supports can be used here by replacing '-' by '_' in the flag name.

Flags without argument must have a boolean value, all other flags require a string value.

Special flags:

name: equivalent of helm template [NAME] parameter. Ignored if name_template is also specified. If neither name_template nor name are specified, the --generate-name flag is used to generate a name.
output_file: name of the single file used to output all the generated resources. This is equivalent to call helm template without specifing output dir. If not specified, each resource is generated into a distinct file.
include_crds and skip_tests: These flags are enabled by default and should be set to false to be removed.
debug: prints the helm debug output in kapitan debug log.
namespace: note that due to the restriction on helm template command, specifying the namespace does not automatically add metadata.namespace property to the resources. Therefore, users are encouraged to explicitly specify it in all resources:
```
metadata:
  namespace: {{ .Release.Namespace }} # or any other custom values
```

See the helm doc for further detail.

Example

Let's use nginx-ingress helm chart as the input. Using kapitan dependency manager, this chart can be fetched via a URL as listed in https://helm.nginx.com/stable/index.yaml.

On a side note, https://helm.nginx.com/stable/ is the chart repository URL which you would helm repo add, and this repository should contain index.yaml that lists out all the available charts and their URLs. By locating this index.yaml file, you can locate all the charts available in the repository.

We can use version 0.3.3 found at https://helm.nginx.com/stable/nginx-ingress-0.3.3.tgz. We can create a simple target file as inventory/targets/nginx-from-chart.yml whose content is as follows:

parameters:
  kapitan:
    vars:
      target: nginx-from-chart
    dependencies:
    - type: https
      source: https://helm.nginx.com/stable/nginx-ingress-0.3.3.tgz
      unpack: True
      output_path: components/charts
    compile:
      - output_path: .
        input_type: helm
        input_paths:
          - components/charts/nginx-ingress
        helm_values:
          controller:
            name: my-controller
            image:
              repository: custom_repo
        helm_params:
          name: my-first-release-name
          namespace: my-first-namespace

To compile this target, run:

$ kapitan compile --fetch
Dependency https://helm.nginx.com/stable/nginx-ingress-0.3.3.tgz : fetching now
Dependency https://helm.nginx.com/stable/nginx-ingress-0.3.3.tgz : successfully fetched
Dependency https://helm.nginx.com/stable/nginx-ingress-0.3.3.tgz : extracted to components/charts
Compiled nginx-from-chart (0.07s)

The chart is fetched before compile, which creates components/charts/nginx-ingress folder that is used as the input_paths for the helm input type. To confirm if the helm_values actually has overridden the default values, we can try:

$ grep "my-controller" compiled/nginx-from-chart/nginx-ingress/templates/controller-deployment.yaml
  name: my-controller
      app: my-controller
        app: my-controller

Building the binding from source

Run

cd kapitan/inputs/helm
./build.sh

This requires Go 1.14.

Helm subcharts

There is an external dependency manager of type helm which enables you to specify helm charts to download, including subcharts.