Deploying a Rails app on a Managed VM with SSL enabled in the config/environments/production.rb as follows:

config.force_ssl = true

causes an infinite redirect loop. It appears that the HTTP_X_FORWARDED_PROTO HTTP header isn’t set properly.

force_ssl relies on the HTTP_X_FORWARDED_PROTO HTTP header to determine whether or not the request was an HTTPS request. If this setting isn't set to https then you end up with an infinite redirect loop as force_ssl will always think the forwarded request isn't HTTPS.

When we deploy Rails to a managed VM it appears each machine is set up with nginx in front? Is it possible for nginx to take care of the header?

Note: With force_ssl enabled I also had to disable health checks as they are sent http (not https) so Rails returned a 301 redirect. This caused the instance to be classified as unhealthy and it wouldn't receive any requests.