Provide writable cache for read-only Nginx

chart/figcraft/templates/resources.yaml

@@ -63,6 +63,7 @@ spec:
           failureThreshold: 3
         volumeMounts:
         - {name: tmp, mountPath: /tmp}
+        - {name: nginx-cache, mountPath: /var/cache/nginx}
       - name: nginx-exporter
         image: {{ .Values.metrics.exporter.image }}
         args: [--nginx.scrape-uri=http://127.0.0.1:8081/nginx_status]
@@ -81,6 +82,8 @@ spec:
       volumes:
       - name: tmp
         emptyDir: {sizeLimit: 1Gi}
+      - name: nginx-cache
+        emptyDir: {sizeLimit: 64Mi}
       {{- with .Values.nodeSelector }}
       nodeSelector: {{- toYaml . | nindent 8 }}
       {{- end }}