Is it possible to define variables use if/else condition in helm chart? - kubernetes-helm

Question

In my values.yaml I have:
isLocal: false
localEnv:
url: abcd
prodEnv:
url: defg
Then I have a service.yaml:
{{- if .Values.isLocal }}
{{- $env := .Values.localEnv }}
{{- else}}
{{- $env := .Values.prodEnv }}
{{- end}}
url: {{ $env.url}}
Unfortunately I got a 'undefined variable "$env"' error, does anyone have idea how to achieve this? Thanks!

Answer 1

One more way would be to create the variable before starting the if/else block. For example:
{{- $env := .Values.prodEnv -}}
{{ if .Values.isLocal }}
{{- $env = .Values.localEnv -}}
{{ end}}
Notice that I've not used the := operator inside the if block as the variable is already created.
and then
url: {{ $env.url}}

Answer 2

The Go text/template documentation notes:
A variable's scope extends to the "end" action of the control structure ("if", "with", or "range") in which it is declared....
so your declarations of $env go out of scope at the end of the {{ if }}...{{ end }} block, which isn't so useful.
Helm also includes (almost all of) a support template library called Sprig which includes a ternary function, which acts sort of like an inline "if" statement. For your example you could write
{{- $env := ternary .Values.localEnv .Values.prodEnv .Values.isLocal -}}
(Also consider just writing totally separate Helm values files for each environment, and installing your chart with helm install -f prod.yaml, instead of trying to encapsulate every possible environment in a single file.)

Answer 3

You actually can define the variable $env outside the if block and assign its value using = with if block.
{{- $env := "" }}
{{- if .Values.isLocal }}
{{- $env = .Values.localEnv }}
{{- else}}
{{- $env = .Values.prodEnv }}
{{- end}}
url: {{ $env.url}}
Please note: := will declare the variable while assigning the value. On the other hand, = will assign the value only.
If you use := in if, it will declare a new local variable $env which will not impact the value of $env declared outside the if block.