Support multiple VIRTUAL_HOSTs per container.

Fixes #3

Dockerfile

@@ -20,8 +20,8 @@ ADD . /app
 RUN wget -P /usr/local/bin https://godist.herokuapp.com/projects/ddollar/forego/releases/current/linux-amd64/forego
 RUN chmod u+x /usr/local/bin/forego
 
-RUN wget https://github.com/jwilder/docker-gen/releases/download/0.2.1/docker-gen-linux-amd64-0.2.1.tar.gz
-RUN tar xvzf docker-gen-linux-amd64-0.2.1.tar.gz
+RUN wget https://github.com/jwilder/docker-gen/releases/download/0.3.0/docker-gen-linux-amd64-0.3.0.tar.gz
+RUN tar xvzf docker-gen-linux-amd64-0.3.0.tar.gz
 
 EXPOSE 80
 ENV DOCKER_HOST unix:///tmp/docker.sock

nginx.tmpl

@@ -6,7 +6,7 @@ server {
 	return 503;
 }
 
-{{ range $host, $containers := groupBy $ "Env.VIRTUAL_HOST" }}
+{{ range $host, $containers := groupByMulti $ "Env.VIRTUAL_HOST" "," }}
 upstream {{ $host }} {
 
 {{ range $index, $value := $containers }}