Merge pull request #235 from thomasleveil/safeguard

refuse to start if the docker sock isn't available

Dockerfile

@@ -30,4 +30,5 @@ ENV DOCKER_HOST unix:///tmp/docker.sock
 
 VOLUME ["/etc/nginx/certs"]
 
+ENTRYPOINT ["/app/docker-entrypoint.sh"]
 CMD ["forego", "start", "-r"]

docker-entrypoint.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+set -e
+
+# Warn if the DOCKER_HOST socket does not exist
+if [[ $DOCKER_HOST == unix://* ]]; then
+	socket_file=${DOCKER_HOST#unix://}
+	if ! [ -S $socket_file ]; then
+		cat >&2 <<-EOT
+			ERROR: you need to share your Docker host socket with a volume at $socket_file
+			Typically you should run your jwilder/nginx-proxy with: \`-v /var/run/docker.sock:$socket_file:ro\`
+			See the documentation at http://git.io/vZaGJ
+		EOT
+		socketMissing=1
+	fi
+fi
+
+# If the user has run the default command and the socket doesn't exist, fail
+if [ "$socketMissing" = 1 -a "$1" = forego -a "$2" = start -a "$3" = '-r' ]; then
+	exit 1
+fi
+
+exec "$@"