I've encountered issue with dropped SSE connection when deployed SSE based sinatra app with SSL certificates and nginx-proxy docker container.
First, create vhost.d directory on host and connect it to /etc/nginx/vhost.d in nginx-proxy container via volume. Create corresponding file to your VIRTUAL_HOST name, which will be included upon nginx startup. In my case that was SSE stream.it-premium.com.ua.
My /home/nexus/vhost.d/stream.it-premium.com.ua file is following
proxy_set_header Connection ''; proxy_http_version 1.1; chunked_transfer_encoding off; proxy_buffering off;
But it has still issues with dropped connection.
Finally I've updated app code with following headers:
response['Cache-control'] = 'no-cache' response['X-Accel-Buffering'] = 'no'
And everything run smoothly after deploy.