Helm dependencies - Reference to values inside the helm dependancy (dependency outputs)-CodePudding

I'll give the context first then the problem: I am interested in centralising a set of values that would be in my values.yaml.

Initial plan was to create a config map with the centralised values that I could load using the lookup helm function. Sadly for me the CD tool I use (ArgoCD) doesn't support lookup.

Current chain of thought would be to create a dummy helm chart that would contain the centralised values. I would set this helm chart as a dependency. Can I get some outputs out of this dependancy that can be used elsewhere? If yes, how to refer to them in the values.yaml?

CodePudding user response：

One approach could be like this:

Create a folder structure such as this

yourappfolder
- Chart.yaml
- value.yaml // the main value file
- value.dev.yaml //contains env-specific values and override value.yaml

and publish a completely new helm chart like my-generic-chart to a registry with default values already placed and update it in Chart.yaml as a dependency

# Chart.yaml
apiVersion: v2
name: myapplication
description: A Helm chart for Kubernetes
type: application
version: 0.1.0
appVersion: "1.16.0"
dependencies:
  - name: my-generic-chart
    version: 5.6.0
    repository: "URL to your my-default-chart"

and don't forget to put all the values under my-default-chart

# values.yaml
my-default-chart:
  image: nginx
  imageTag: 1
  envs:
    log-format: "json"
    log-level: "none"
    ..
    ..

# values.dev.yaml
my-default-chart:
  imageTag: 1.1
  envs:
    log-level: "debug"
    ..
    ..

the values.dev.yaml file will override the values in values.yaml and both of them together will override the values in the generic chart default values.yaml file.

Now you have to create a generic chart that fits to all of your applications or create a generic chart for each type of application

CodePudding user response：

Figured it is possible by 2 ways:

Exporting/Importing child values: https://helm.sh/docs/topics/charts/#importing-child-values-via-dependencies and I found a great related answer: How to use parameters of one subchart in another subchart in Helm
Using "Templates": https://helm.sh/docs/chart_template_guide/subcharts_and_globals/#sharing-templates-with-subcharts "Parent charts and subcharts can share templates. Any defined block in any chart is available to other charts."

I create one chart "data" that doesn't create anything but creates template function (for example "data.project") then I use another

├── Chart.lock
├── Chart.yaml
├── charts
│   ├── data
│   │   ├── Chart.yaml
│   │   ├── templates
│   │   │   └── _helpers.tpl
│   │   └── values.yaml
│   ├── sub0
│   │   ├── Chart.yaml
│   │   ├── templates
│   │   │   └── configmap.yaml
│   │   └── values.yaml
└── values.yaml

charts/data/templates/_helpers.tpl contains:

{{- define "data.project" -}}
    project_name
{{- end }}

The top Chart.yaml contains:

---
apiVersion: v2
name: multi
type: application
version: 0.1.0
appVersion: "1.16.0"

dependencies:
  - name: data
    version: 0.1.0
    repository: "file://charts/data" # This is while testing locally, once shared in a central repository this will achieve the centralised data information
    import-values:
      - data
  - name: sub0
    version: 0.1.0
    repository: "file://charts/sub0"

Then from anywhere I can do:

"{{ include \"data.project\" . }}"

And obtain the value

Of course the "data" chart will need to live in a separate repository