✨(helm) allow to load custom theme file in a configMap

In order to load a custom theme file with our helm chart, we allow to
load the content of a file into a config map and then use this configmap
as a volume in the backend deployment

src/helm/impress/templates/backend_deployment.yaml

@@ -90,6 +90,11 @@ spec:
               subPath: {{ .subPath | default "" }}
               readOnly: {{ .readOnly }}
             {{- end }}
+            {{- if .Values.backend.themeCustomization.enabled }}
+            - name: theme-customization
+              mountPath: {{ .Values.backend.themeCustomization.mount_path }}
+              readOnly: true
+            {{- end }}
       {{- with .Values.backend.nodeSelector }}
       nodeSelector:
         {{- toYaml . | nindent 8 }}
@@ -117,6 +122,11 @@ spec:
             claimName: "{{ $fullName }}-{{ $name }}"
           {{- end }}
         {{- end }}
+        {{- if .Values.backend.themeCustomization.enabled }}
+        - name: theme-customization
+          configMap:
+            name: docs-theme-customization
+        {{- end }}
         {{- range .Values.backend.extraVolumes }}
         - name: {{ .name }}
           {{- if .existingClaim }}

src/helm/impress/templates/theme_customization_file_cm.yaml

@@ -0,0 +1,10 @@
+{{- if .Values.backend.themeCustomization.enabled }}
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: docs-theme-customization
+  namespace: {{ .Release.Namespace }}
+data:
+  default.json: |
+    {{ .Values.backend.themeCustomization.file_content | toJson | indent 4 }}
+{{- end }}