Is there a way to create an iterable list from a string?

user_9692227 0
Viewed 266

I'm passing the following string through values.yaml:

urls: http://example.com http://example2.com http://example3.com

Is there a way to create a list from this, so i can then do something like:

{{ range $urls }}
{{ . }}
{{ end }}

The problem is I'm passing the urls var in a dynamic fashion, and I'm also can't avoid using a single string for that (ArgoCD ApplicationSet wont let me pass a list).

go-templates kubernetes-helm kubernetes templates yaml
2 Answers

Basically all you need is just add this line in your template yaml:

{{- $urls := splitList " " .Values.urls }}

It will import urls string from values.yaml as the list so you will be able run your code which you posted in your question.

Simple example based on helm docs:

  1. Let's get simple chart used in helm docs and prepare it:

    helm create mychart
rm -rf mychart/templates/*

  2. Edit values.yaml and insert urls string:

    urls: http://example.com http://example2.com http://example3.com

  3. Create ConfigMap in templates folder (name it configmap.yaml)

    apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Release.Name }}-configmap
data:
  {{- $urls := splitList " " .Values.urls }}
  urls: |- 
    {{- range $urls }}
    - {{ . }}
    {{- end }}

    As can see, I'm using your loop (with "- " to avoid creating empty lines).

  4. Install chart and check it:

    helm install example ./mychart/
helm get manifest example

    Output:

    ---
# Source: mychart/templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: example-configmap
data:
  urls: |-
    - http://example.com
    - http://example2.com
    - http://example3.com
user_163919910

Split by spaces to get an array of urls.

{{- range _, $v := $urls | split " " }}
{{ $v }}
{{- end }}
user_88718910
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