Prevent generating broken config

Fixes #115

Dockerfile

@@ -17,7 +17,7 @@ RUN echo "daemon off;" >> /etc/nginx/nginx.conf \
 RUN wget -P /usr/local/bin https://godist.herokuapp.com/projects/ddollar/forego/releases/current/linux-amd64/forego \
  && chmod u+x /usr/local/bin/forego
 
-ENV DOCKER_GEN_VERSION 0.3.9
+ENV DOCKER_GEN_VERSION 0.4.0
 
 RUN wget https://github.com/jwilder/docker-gen/releases/download/$DOCKER_GEN_VERSION/docker-gen-linux-amd64-$DOCKER_GEN_VERSION.tar.gz \
  && tar -C /usr/local/bin -xvzf docker-gen-linux-amd64-$DOCKER_GEN_VERSION.tar.gz \

nginx.tmpl

@@ -58,11 +58,13 @@ upstream {{ $host }} {
 		{{ end }}
 	{{/* Else default to standard web port 80 */}}
 	{{ else }}
-		{{ range $address := $container.Addresses }}
-			{{ if eq $address.Port "80" }}
+		{{ $address := where $container.Addresses "Port" "80" | first }}
+		{{ if $address }}
 			# {{$container.Name}}
-			server {{ $address.IP }}:{{ $address.Port }};
-			{{ end }}
+			server {{ $address.IP }}:80;
+		{{ else }}
+			# {{$container.Name}}
+			server {{ $container.IP }} down;
 		{{ end }}
 	{{ end }}
 {{ end }}