Created question in FIWARE Q/A platform on 02-05-2019 at 13:05
Please, ANSWER this question AT https://stackoverflow.com/questions/55951377/wirecloud-widgets-operators-not-loaded-by-nginx-running-on-remote-server

Question:
Wirecloud Widgets/Operators not loaded by nginx running on remote server

Description:
I am designing a wirecloud dashboard using a fiware-wirecloud instance hosted remotely. I understand the nginx server actually doesn't load the widgets when I point my browser to that wirecloud instance, despite the fact that wirecloud started (and I can login). I can confirm that the widgets are available in the wirecloud-data directory.

$ls wirecloud-data/catalogue_resources/
CoNWeT

$ls wirecloud-data/catalogue_resources/CoNWeT/
ckan2poi map-viewer ngsi-source NSGI map visualization example union-list
googlecharts ngsi-browser ngsi-subscription-browser ol3-map video-player-widget
json-editor ngsi-datamodel2poi ngsi-type-browser orion-admin-mashup web-browser
linear-graph ngsientity2poi ngsi-updater simple-history-module2linear-graph youtube-browser

Unfortunately, when I access wirecloud via the browser, they don't get loaded, here is the nginxserver log (not showing/loading anything):

$docker logs -f fiware-nginx

I tested same versions of wirecloud and widgets locally, they are working fine.

$ ls wirecloud-data/catalogue_resources/
CoNWeT WireCloud

$ ls wirecloud-data/catalogue_resources/CoNWeT/
NSGI map visualization example googlecharts ngsi-source photo-viewer
bae-browser json-editor ngsi-subscription-browser simple-history-module2linear-graph
bae-details linear-graph ngsi-target union-list
bae-marketplace map-viewer ngsi-type-browser video-player-widget
bae-search-filters markdown-editor ngsi-updater web-browser
ckan-source markdown-viewer ngsientity2poi youtube-browser
ckan-source-from-url ngsi-browser ol3-map
ckan2poi ngsi-datamodel2poi orion-admin-mashup

As you can see below, as soon as I access the local instance, widgets get loaded and shown in the local nginx server log

$ docker logs -f fiware-nginx
172.20.0.1 - - [02/May/2019:10:40:43 +0000] "GET / HTTP/1.1" 302 0 "" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36" ""
172.20.0.1 - - [02/May/2019:10:40:52 +0000] "GET /wirecloud/home HTTP/1.1" 200 1377 "" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36" ""
2019/05/02 10:40:52 [warn] 6#6: *1 upstream sent more data than specified in "Content-Length" header while reading upstream, client: 172.20.0.1, server: example.org, request: "GET /api/context?theme=wirecloud.defaulttheme HTTP/1.1", upstream: "http://172.20.0.9:8000/api/context?theme=wirecloud.defaulttheme", host: "localhost", referrer: "http://localhost/wirecloud/home"

I noticed on the local machine, a directory WireCloud located under wirecloud-data/catalogue_resources/ which is not created on the remote instance, could that be the issue?

Localhost:

$ ls wirecloud-data/catalogue_resources/
CoNWeT WireCloud
$ ls wirecloud-data/catalogue_resources/WireCloud/
workspace-browser

Remote:

$ls wirecloud-data/catalogue_resources/
CoNWeT

EDIT: Here's the warn message I found in the server error log[nginx_logs/error.log] file:

2019/05/02 09:11:11 [warn] 6#6: *6 upstream sent more data than specified in "Content-Length" header while reading upstream, client: 193.136.xx.xxx, server: , request: "GET /api/context?theme=wirecloud.defaulttheme HTTP/1.1", upstream: "http://172.21.0.7:8000/api/context?theme=wirecloud.defaulttheme", host: "193.136.xx.xx:xxxxx", referrer: "http://193.136.xx.xx:xxxxx/wirecloud/home"
2019/05/02 09:11:12 [warn] 6#6: *8 upstream sent more data than specified in "Content-Length" header while reading upstream, client: 193.136.xx.xxx, server: , request: "GET /api/preferences/platform HTTP/1.1", upstream: "http://172.21.0.7:8000/api/preferences/platform", host: "193.136.xx.xx:xxxxx", referrer: "http://193.136.xx.xx:xxxxx/wirecloud/home"

Cc: Álvaro Arranz