Looping with helm - kubernetes

Question

I'm reading the helm documentation about how to do some loops for Kubernetes, basically what i want to do is something like this.
What i have...
values.yaml
dnsAliases:
- test1
- test2
- test3
on services-external.yaml
{{- if and .Values.var1.var1parent (eq .Values.var2.var2parent "value") }}
{{- range .Values.dnsAliases }}
apiVersion: v1
kind: Service
metadata:
name: name-{{ . }} ( for creating the name "name-test1/test2 and so on"
spec:
type: ExternalName
externalName: {{ .Values.var3.var3parent }}-{{ .Values.var4.var4parent }}-{{ .}}.svc.cluster.local
ports:
- port: 80
protocol: TCP
targetPort: 80
{{ end }}
{{ end }}
but im having the error
Error: UPGRADE FAILED: render error in "services-external.yaml": template: templates/services-external.yaml:312:32: executing "services-external.yaml" at <.Values.var3.var3parent>: can't evaluate field Values in type interface {}
I tried also with "with" but same error. Is there some way to achieve it by using the "if" with a loop on helm?

Answer 1

Error you have shows that template can't find values for <.Values.var3.var3parent>. Since you're using range block, . refers to local variables within the loop. You need to refer to global variables. This can be achieved with two approaches:
Use $ before a variable you need to invoke (see it with var3)
Define a new variable and save values you need to this variable (see it with var4)
Here's a tested template with two approaches from the above:
{{- if and .Values.var1.var1parent (eq .Values.var2.var2parent "value") }}
{{- $var4 := .Values.var4 -}}
{{- range .Values.dnsAliases }}
apiVersion: v1
kind: Service
metadata:
name: name-{{ . }} ( for creating the name "name-test1/test2 and so on"
spec:
type: ExternalName
externalName: {{ $.Values.var3.var3parent }}-{{ $var4.var4parent }}-{{ .}}.svc.cluster.local
ports:
- port: 80
protocol: TCP
targetPort: 80
{{ end }}
{{ end }}
You can read about it more here
Also there is one more possible solution for this to reset the scope to root and work with loop as usually (but it's more sketchy approach) (here's a link)

Answer 2

Thanks #moonkotte i managed to make it work using the approach of defining a new variable to save the scope, here the example.
On values.yaml
dnsShortNames:
short1: "short1"
short2: "short2"
short3: "short3"
dnsAliases:
- test1
- test2
- test3
on services-external.yaml
{{- $dns_short_names := .Values.dnsShortNames }}
{{- range .Values.dnsAliases }}
---
apiVersion: v1
kind: Service
metadata:
name: name-{{ . }}
spec:
type: ExternalName
externalName: {{ $dns_short_names.short1 }}-{{ $dns_short_names.short2 }}-{{ $dns_short_names.short3 }}{{.}}.svc.cluster.local
ports:
- port: 80
protocol: TCP
targetPort: 80
{{- end }}
Applying this Kubernetes will create 3 different external services.
short1-short2-short3.test1.svc.cluster.local
short1-short2-short3.test2.svc.cluster.local
short1-short2-short3.test3.svc.cluster.local
Public thanks to my friend Xavi <3.