Helm Template If/Else
External
Internal
Overview
if/else can be used to create conditional blocks.
The if control structures evaluate pipelines, not just values (values are a special case of a pipeline):
{{ if PIPELINE }}
# Do something
{{ else if OTHER_PIPELINE }}
# Do something else
{{ else }}
# Default case
{{ end }}
A pipeline evaluates to false if the result of the pipeline, or the value, is:
- a boolean false
- a numeric zero
- an empty string
- a
nil(empty or null) - an empty collection (map, slice, tuple, dict, array).
In any other case, the condition is evaluated to true.
Example:
{{ if .Values.debug }}
# Do something
{{ else }}
# Do something else
{{ end }}
nil pointer evaluating interface
While nil (missing) values are evaluated to false, this only applies to the leaf of the YAML path. All intermediate path elements leading to the leaf must exist, and must NOT be empty, otherwise the template rendering engine will error out with:
Error: template: simplest/templates/configmap.yaml:6:16: executing "simplest/templates/configmap.yaml" at <.Values.appearance.color>: nil pointer evaluating interface {}.color
The above failure was generated by the expression:
{{- if .Values.appearance.color }} ...
where values.yaml is
appearance:
Expressions
if expressions are built with functions: eq, ne, lt, gt, and, or, so the function name is provided first, followed by the arguments. Functions can be grouped with ( ).
Testing the Existence of Two Configuration Elements in the Same Expression
{{- if or .Values.myApp.config.local .Values.myApp.config.nfs }}
...
{{- end }}
Testing the Non-Existence of a Configuration Element
The following conditional evaluates to true and the embedded content is rendered if the configuration element does NOT exist:
{{- if not .Values.myApp.something }}
...
{{- end }}
Testing Equality and Inequality of Values
{{- if eq .Values.myApp.color "blue" }}
...
{{- end }}
{{- if ne .Values.myApp.color "blue" }}
...
{{- end }}
{{- if eq .Values.myApp.something .Values.myApp.somethingElse }}
...
{{- end }}
{{- if and (eq .Values.myApp.color "blue") (eq .Values.myApp.shape "square") }}
...
{{- end }}