Add location for serving challenges.

docker/nginx/conf/nginx-site.conf

@@ -38,6 +38,12 @@ server {
       root /code;
     }
 
+    # Let's encrypt certonly
+    location '/.well-known/acme-challenge' {
+      default_type "text/plain";
+      root        /tmp/letsencrypt-auto;
+    }
+
     location @proxy_to_app {
       proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
       # enable this if and only if you use HTTPS