How to create template in the helm chart? - kubernetes

Question

I need to create template for secret value.
This is the secret file:
apiVersion: v1
kind: Secret
metadata:
name: secret
type: Opaque
stringData:
"user": "user"
"password": "password"
And this is what I have created in the _helpers.tpl
{{/*
User
*/}}
{{- define "##chartName##.user" -}}
{{- $secret := lookup "v1" "Secret" .Release.Namespace "secret" -}}
{{- if $secret -}}
{{- print $secret.stringData.user}}
{{- else -}}
{{- fail "The secret is absent" -}}
{{- end -}}
{{- end -}}
But it doesn't work and I get the error : <$secret.stringData.user>: nil pointer evaluating interface {}.user
I have created the secret before installation helm chart and I don't know what is the reason of this error. Thanks for any help!

Answer 1

You will get that error if $secret exists, but doesn't contain stringData.
At a Helm level, you can work around this by using the default function to force it to exist ("doesn't have stringData" and "doesn't have user" are approximately the same error):
{{- $secret := lookup "v1" "Secret" .Release.Namespace "secret" | default dict -}}
{{- $stringData := $secret.stringData | default dict -}}
{{- $stringData.user | required "The secret is absent" -}}
At a higher-level, if it's possible to read back the Secret, it probably only has the base64-encoded data field (even if it was created with stringData). Helm provides a b64dec function that could decode it. It'd be better to refer to the secret as an environment variable in your pod spec, or pass the value directly into Helm.
# in a Pod spec; without using Helm `lookup`
env:
- name: USER
valueFrom:
secretKeyRef:
name: secret
key: user
# or passed directly via Helm
{{- $credentials := .Values.credentials | default dict -}}
{{- $credentials.user | required "missing user.credentials" -}}