First obtain a copy of the ca cert for your corporate proxy that is spoofing your SSL certificates.
Once you have it, you’ll need to add it in to the container, by running the following substituting the name of your cms-web container:
docker cp mycert.pem xibo_cms-web_1:/usr/local/share/ca-certificates
docker exec -ti xibo_cms-web_1 update-ca-certificates
docker restart xibo_cms-web_1
That should add your certificate, and the CMS should be able to connect to the Darksky servers.
If not, please run the following
docker exec -ti xibo_cms-web_1 sh
curl -v https://api.darksky.net
exit
What is returned?