Helm with nested lists using range - kubernetes

Question

I have the following content in values.yaml and virtualservice.yaml:
I want to create template file using above value but getting error while helm rendenring template.
values.yaml:
istio:
enabled: true
virtualService:
enabled: true
virtualServices:
"0":
name: hello-app
gateways:
- gateway-new
hosts:
- prod.abc.com
apps:
name: primary
path: "/api"
routes:
"0":
weight: 100
port: 8080
name: hello-app
"1":
weight: 0
port: 8080
name: hello-app-canary
"1":
name: hello-app-internal
gateways:
- mesh
hosts:
- hello-app.test.prod.svc.cluster.local
apps:
name: internal
path: "/api"
routes:
"0":
weight: 100
port: 9081
name: hello-app
"1":
weight: 0
port: 9081
name: hello-app-canary
virtualservice.yaml:
{{- if ((.Values.istio).enabled) }}
{{- if ((.Values.istio.virtualService).enabled) }}
{{- range $key, $value := .Values.istio.virtualService.virtualServices }}
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
name: {{ .name }}
namespace: {{ $.Release.Namespace }}
labels:
{{ include "common.labels" $ | indent 4 }}
spec:
gateways:
{{- range .gateways }}
- {{.}}
{{- end }}
hosts:
{{- range .hosts }}
- {{.}}
{{- end }}
http:
{{- range $app := $value.apps }}
- match:
- uri:
prefix: "/{{ $app.path }}"
name: {{ $app.name }}
route:
{{- range $route := $app.routes }}
- destination:
host: {{ $route.name }}
port:
number: {{ $route.port }}
weight: {{ $route.weight }}
{{- end }}
{{- end }}
{{- end }}
{{- end }}
{{- end }}
How do I iterate if I have more than one list using range? With the above template, I am getting the error:
at <$app.path>: can't evaluate field path in type interface {}
Any help is highly appreciated.

Answer 1

First of all, it looks like the virtual service "1" has one extra indent (right now it is under virtual service "0" section, but it should be under "virtualServices").
Moreover, If you want to iterate over the apps of each virtual service, the apps field should be a list, but right now it is a dictionary. Therefore, when you iterate with range $app := $value.apps you are actually iterating over the fields of apps, which leads to the error you are getting.
Here's the fixed version of values.yam:
istio:
enabled: true
virtualService:
enabled: true
virtualServices:
"0":
name: hello-app
gateways:
- gateway-new
hosts:
- prod.abc.com
apps:
- name: primary
path: "/api"
routes:
"0":
weight: 100
port: 8080
name: hello-app
"1":
weight: 0
port: 8080
name: hello-app-canary
"1":
name: hello-app-internal
gateways:
- mesh
hosts:
- hello-app.test.prod.svc.cluster.local
apps:
- name: internal
path: "/api"
routes:
"0":
weight: 100
port: 9081
name: hello-app
"1":
weight: 0
port: 9081
name: hello-app-canary