HAProxy configuration (gist for http://www.davole.com/2017/haproxy-for-docker-containers)

haproxy.cfg

global
	tune.ssl.default-dh-param 2048
	maxconn 100
	daemon

defaults
	mode http

	timeout connect  4s
	timeout http-request  1s
	timeout http-keep-alive  120s
	timeout client  1m
	timeout server  1m
	timeout queue  10s

	option splice-auto
	option dontlog-normal
	option tcp-smart-accept
	option tcp-smart-connect
	option forwardfor
	option http-keep-alive
	
	http-reuse safe

frontend www-http
	bind :80
	reqadd X-Forwarded-Proto:\ http
	
	# hosts
	acl host_frn hdr(host) -i front.example.com
	acl host_bck hdr(host) -i back.example.com

	# https redirect
	redirect scheme https code 301 if !{ ssl_fc } host_frn OR !{ ssl_fc } host_bck

frontend www-https
	bind :443 ssl crt /usr/local/etc/haproxy/example.com.pem
	reqadd X-Forwarded-Proto:\ https
	
	# hosts
	acl host_frn hdr(host) -i front.example.com
	acl host_bck hdr(host) -i back.example.com
	
	# backends
	use_backend front if host_frn
	use_backend front if host_bck

resolvers docker
	nameserver dns1 127.0.0.11:53

backend front
	server front frn:80 check inter 10s resolvers docker

backend back
	server back bck:80 check inter 10s resolvers docker