fix: pass REDIS_PASSWORD to metrics exporter when auth is enabled

[jessebye]

Passes the REDIS_PASSWORD env to the metrics exporter container when auth is enabled. This resolves #135

[gaelgoth]

Hi @jessebye 👋

I’m planning to use a dedicated redis user for the exporter, as described in the docs:
https://github.com/oliver006/redis_exporter/blob/master/README.md?plain=1#L260

Would it be possible to make this more flexible and allow configuring a different user if needed? For example:

Suggested change

	env:
	- name: REDIS_ALIAS
	value: {{ include "valkey.fullname" . }}
	{{- if .Values.auth.enabled }}
	- name: REDIS_PASSWORD
	valueFrom:
	secretKeyRef:
	{{- if .Values.auth.usersExistingSecret }}
	{{- $defaultUser := index .Values.auth.aclUsers "default" | default dict }}
	{{- $passwordKey := $defaultUser.passwordKey | default "default" }}
	name: {{ .Values.auth.usersExistingSecret }}
	key: {{ $passwordKey }}
	{{- else }}
	name: {{ include "valkey.fullname" . }}-auth
	key: default-password
	{{- end }}
	{{- end }}
	env:
	- name: REDIS_ALIAS
	value: {{ include "valkey.fullname" . }}
	{{- if .Values.auth.enabled }}
	- name: REDIS_USER
	value: {{ .Values.metrics.exporter.user | default "default" }}
	- name: REDIS_PASSWORD
	valueFrom:
	secretKeyRef:
	{{- if .Values.auth.usersExistingSecret }}
	{{- $metricsUser := .Values.metrics.exporter.user | default "default" }}
	{{- $userConfig := index .Values.auth.aclUsers $metricsUser | default dict }}
	{{- $passwordKey := $userConfig.passwordKey | default $metricsUser }}
	name: {{ .Values.auth.usersExistingSecret }}
	key: {{ $passwordKey }}
	{{- else }}
	name: {{ include "valkey.fullname" . }}-auth
	key: default-password
	{{- end }}
	{{- end }}

Then it can allow dedicated redis user:

    auth:
      enabled: true
      usersExistingSecret: test-valkey-auth
      aclUsers:
        default:
          permissions: "~* &* +@all"
          passwordKey: default
        monitor:
          permissions: >- # Limited permissions for monitoring: https://github.com/oliver006/redis_exporter/blob/master/README.md?plain=1#L260
            ~* &* -@all +@connection +memory -readonly +strlen +config|get +xinfo
            +pfcount -quit +zcard +type +xlen -readwrite -command +client -wait
            +scard +llen +hlen +get +eval +slowlog +cluster|info +cluster|slots
            +cluster|nodes -hello -echo +info +latency +scan -reset -auth -asking
          passwordKey: monitor

[jessebye]

@gaelgoth that seems reasonable, but does go outside the scope of this PR a bit. perhaps this could be added first, then a separate PR that adds support for using a different user in the metrics exporter?

[gaelgoth]

I’m fine shipping this part first, and then adding support for extra users in metrics exporter 👍🏾