helm nested variable reference not happening - kubernetes-helm

Question

I am not able to reference variable inside a nested variable in Helm. I am not able to do this nested reference, I want to retrieve app1_image and app1_tag using the value of the apps_label variable. How can I do that?
values.yaml:
apps:
- name: web-server
label: app1
command: /root/web.sh
port: 80
- name: app-server
label: app2
command: /root/app.sh
port: 8080
app1_image:
name: nginx
tag: v1.0
app2_image:
name: tomcat
tag: v1.0
deployment.yaml:
{{- range $apps := .Values.apps
apiVersion: apps/v1
kind: Deployment
metadata:
name: {{ $apps.name }}
labels:
app: {{ $apps.name }}
spec:
replicas: 1
selector:
matchLabels:
app:
template:
metadata:
labels:
app: {{ $apps.name }}
spec:
containers:
- name: {{ $apps.name }}
image: {{ $.Values.$apps.label.image }}: {{ $.Values.$apps.label.tag }}
ports:
- containerPort: {{ $apps.port}}
{{- end }}

Answer 1

The core Go text/template language includes an index function that you can use as a more dynamic version of the . operator. Given the values file you show, you could do the lookup (inside the loop) as something like:
{{- $key := printf "%s_image" $apps.label }}
{{- $settings := index $.Values $key | required (printf "could not find top-level settings for %s" $key) }}
- name: {{ $apps.name }}
image: {{ $settings.image }}:{{ $settings.tag }}
You could probably rearrange the layout of the values.yaml file to make this clearer. You also might experiment with what you can provide with multiple helm install -f options to override options at install time; if you can keep all of these settings in one place it is easier to manage.