[hotfix] Fix postgres_exporter secret (!79)

Reviewed-on: https://git.avroid.tech/K8s/k8s-configs/pulls/79

clusters/k8s-avroid-office.prod.local/namespaces/cloud-prod/monitoring/postgres-exporter/values-ovveride.yaml

@@ -21,13 +21,6 @@ serviceAccount:
   # If not set and create is true, a name is generated using the fullname template
   name: vault
 
-config:
-  # define an existing secret to be mounted as the config file
-  # needs to have the key 'postgres_exporter.yml'
-  existingSecret:
-    enabled: true
-    name: "postgres-exporter-secret"
-
 nodeSelector:
   node-role.kubernetes.io/worker: ""
 
@@ -44,3 +37,19 @@ deployment:
     vault.security.banzaicloud.io/vault-role: "cloud-prod"
     vault.security.banzaicloud.io/vault-skip-verify: "false"
     vault.security.banzaicloud.io/vault-path: "avroid-office"
+
+# Additional volumes, e. g. for secrets used in an extraContainer
+extraVolumes:
+  - name: postgres-exporter-config
+    secret:
+      defaultMode: 420
+      items:
+        - key: postgres_exporter.yml
+          path: postgres_exporter.yml
+      secretName: postgres-exporter-secret
+
+# Additional volume mounts
+extraVolumeMounts:
+  - name: postgres-exporter-config
+    mountPath: /etc/postgres_exporter.yml
+    subPath: postgres_exporter.yml