Difference between revisions of "Helm Template range"

From NovaOrdis Knowledge Base
Jump to: navigation, search
(Iterating over a .Values List)
(Iterating over a Complex Structure)
 
(7 intermediate revisions by the same user not shown)
Line 9: Line 9:
 
=Overview=
 
=Overview=
  
<tt>range</tt> provides a "for each" loop. The simples way to access the current iteration element is with {{ . }}. [[Helm_Templates#Template_Variables|Variables]] can also be used.
+
<tt>range</tt> provides a "for each" loop. It "ranges over".
 +
 
 +
The range operator sets the scope to ".", so the simples way to access the current iteration element is with {{ . }} [[Helm_Templates#Template_Variables|Variables]] can also be used.
 +
 
 +
=Playground=
 +
{{External|https://github.com/ovidiuf/playground/tree/master/helm/if-and-range}}
  
 
=Iterating over an In-Line List=
 
=Iterating over an In-Line List=
Line 65: Line 70:
 
=Iterating over a Map=
 
=Iterating over a Map=
  
=Numeric Iteration Variable=
+
It uses [[Helm_Templates#Template_Variables|variables]].
 +
 
 +
values.yaml:
 +
<syntaxhighlight lang='yaml'>
 +
shapes:
 +
  FIRST_SHAPE: square
 +
  SECOND_SHAPE: circle
 +
  THIRD_SHAPE: triangle
 +
</syntaxhighlight>
 +
 
 +
Template:
 +
<syntaxhighlight lang='yaml'>
 +
env:
 +
{{- range $k, $v := .Values.shapes }}
 +
- name: {{ $k }}
 +
  value: {{ $v | upper -}}
 +
{{ end }}
 +
</syntaxhighlight>
 +
 
 +
Result:
 +
<syntaxhighlight lang='yaml'>
 +
env:
 +
- name: FIRST_SHAPE
 +
  value: SQUARE
 +
- name: SECOND_SHAPE
 +
  value: CIRCLE
 +
- name: THIRD_SHAPE
 +
  value: TRIANGLE
 +
</syntaxhighlight>
 +
 
 +
=Iterating over a Complex Structure=
 +
values.yaml:
 +
<syntaxhighlight lang='yaml'>
 +
volumesAndMounts:
 +
  volumes:
 +
    - name: mount-0
 +
      hostPath:
 +
        path: /tmp
 +
    - name: mount-1
 +
      hostPath:
 +
        path: /tmp
 +
  volumesMounts:
 +
    - mountPath: /a
 +
      name: mount-0
 +
    - mountPath: /b
 +
      name: mount-1
 +
</syntaxhighlight>
 +
 
 +
Template:
 +
<syntaxhighlight lang='yaml'>
 +
kind: Pod
 +
[...]
 +
spec:
 +
  containers:
 +
    - name: ...
 +
      [...]
 +
      volumeMounts:
 +
        {{- range .Values.volumesAndMounts.volumesMounts }}
 +
        - {{- . | toYaml | nindent 10 -}}
 +
        {{- end }}
 +
  volumes:
 +
    {{- range .Values.volumesAndMounts.volumes }}
 +
    - {{ . | toYaml | nindent 6 -}}
 +
    {{- end }}
 +
</syntaxhighlight>

Latest revision as of 01:01, 10 October 2019

External

Internal

Overview

range provides a "for each" loop. It "ranges over".

The range operator sets the scope to ".", so the simples way to access the current iteration element is with {{ . }} Variables can also be used.

Playground

https://github.com/ovidiuf/playground/tree/master/helm/if-and-range

Iterating over an In-Line List

env:
{{- range list "blue" "red" "green" }}
- name: {{ . | upper | printf "COLOR_%s" }}
  value: {{ . -}}
{{ end }}

The result is:

env:
- name: COLOR_BLUE
  value: blue
- name: COLOR_RED
  value: red
- name: COLOR_GREEN
  value: green

Iterating over a .Values List

values.yaml:

colors:
  - blue
  - red
  - green
  - yellow

Template:

env:
{{- range .Values.colors }}
- name: {{ . | upper | printf "COLOR_%s" }}
  value: {{ . -}}
{{ end }}

Result:

env:
- name: COLOR_BLUE
  value: blue
- name: COLOR_RED
  value: red
- name: COLOR_GREEN
  value: green
- name: COLOR_YELLOW
  value: yellow

Iterating over a Map

It uses variables.

values.yaml:

shapes:
  FIRST_SHAPE: square
  SECOND_SHAPE: circle
  THIRD_SHAPE: triangle

Template:

env:
{{- range $k, $v := .Values.shapes }}
- name: {{ $k }}
  value: {{ $v | upper -}}
{{ end }}

Result:

env:
- name: FIRST_SHAPE
  value: SQUARE
- name: SECOND_SHAPE
  value: CIRCLE
- name: THIRD_SHAPE
  value: TRIANGLE

Iterating over a Complex Structure

values.yaml:

volumesAndMounts:
  volumes:
    - name: mount-0
      hostPath:
        path: /tmp
    - name: mount-1
      hostPath:
        path: /tmp
  volumesMounts:
    - mountPath: /a
      name: mount-0
    - mountPath: /b
      name: mount-1

Template:

kind: Pod
[...]
spec:
  containers:
    - name: ...
      [...]
      volumeMounts:
        {{- range .Values.volumesAndMounts.volumesMounts }}
        - {{- . | toYaml | nindent 10 -}}
        {{- end }}
  volumes:
    {{- range .Values.volumesAndMounts.volumes }}
    - {{ . | toYaml | nindent 6 -}}
    {{- end }}