make repository url an runtime env var

Dockerfile

@@ -17,5 +17,4 @@ ADD starter /usr/local/bin/
 EXPOSE 80
 WORKDIR /repo
 
-RUN git clone "$GIT_URL" .
 CMD /usr/local/bin/starter

starter

@@ -25,8 +25,17 @@ function update() {
 	rm -rf /var/www/html-delme &
 	git reset --hard
 }
+function init() {
+	test -z "$GIT_URL" && {
+		echo "GIT_URL is not set"
+		exit 1
+	}
+	git clone "$GIT_URL" .
+}
 
 cd /repo
+
+init
 update
 (
 	while true; do