Helm - Templating variables in values.yaml - kubernetes

Question

I'm trying to template variables from a map inside the values.yaml into my final Kubernetes ConfigMap YAML.
I've read through https://github.com/helm/helm/issues/2492 and https://helm.sh/docs/chart_template_guide/ but can't seem to find an answer.
For some context, this is roughly what I'm trying to do:
values.yaml
config:
key1: value
key2: value-{{ .Release.Name }}
configmap.yaml
kind: ConfigMap
data:
config-file: |
{{- range $key, $value := .Values.config }}
{{ $key }} = {{ $value }}
{{- end }}
Where the desired output with would be:
helm template --name v1 mychart/
kind: ConfigMap
data:
config-file: |
key1 = value
key2 = value-v1
I've tried a few variations using template functions and pipelining, but to no avail:
{{ $key }} = {{ tpl $value . }}
{{ $key }} = {{ $value | tpl . }}
{{ $key }} = {{ tpl $value $ }}

Answer 1

The above would also have worked in this way
values.yaml
config:
key1: "value"
key2: "value-{{ .Release.Name }}"
configmap.yaml
kind: ConfigMap
data:
config-file: |
{{- range $key, $value := .Values.config }}
{{ $key }} = {{ tpl $value $ }}
{{- end }}
What I changed was : I put value in quotes in value.yaml and used template tpl in the config map.

Answer 2

I'll refer to the question's title regarding templating variables in helm and suggest another option to use on values.yaml which is YAML Anchors.
Docs reference
As written in here:
The YAML spec provides a way to store a reference to a value, and
later refer to that value by reference. YAML refers to this as
"anchoring":
coffee: "yes, please"
favorite: &favoriteCoffee "Cappucino"
coffees:
- Latte
- *favoriteCoffee
- Espresso
In the above, &favoriteCoffee sets a reference to Cappuccino.
Later, that reference is used as *favoriteCoffee.
So coffees becomes Latte, Cappuccino, Espresso.
A more practical example
Referring to a common image setup (Registry and PullPolicy) in all values.yaml.
Notice how the default values are being set at Global.Image next to the reference definition which starts with &:
Global:
Image:
Registry: &global-docker-registry "12345678910.dkr.ecr.us-west-2.amazonaws.com" # <--- Default value
PullPolicy: &global-pull-policy "IfNotPresent" # <--- Default value
Nginx:
Image:
Registry: *global-docker-registry
PullPolicy: *global-pull-policy
Version: 1.21.4
Port: 80
MySql:
Image:
Registry: *global-docker-registry
PullPolicy: *global-pull-policy
Name: mysql
Version: 8.0.27
Port: 3306

Answer 3

Managed to solve this using the following syntax:
configmap.yaml
kind: ConfigMap
data:
config-file: |
{{- range $key, $value := .Values.config }}
{{ $key }} = {{ tpl ($value | toString) $ }}
{{- end }}

Answer 4

there is fight in this PR here about this topic.
I know that it's possible now, but this require maintenance of the chart to be in-house (e.g. answer of Amrut ).
Let's summarize :
To have templating in values.yaml , these are the available options:
helm may support that in future ( watch this thread about this topic.)
use tpl function inside the chart
use another tool on top of helm : terraform or helmfile.