Allow using alternate apt repository

Author: fpytloun

Diff for: Dockerfile

@@ -1,11 +1,14 @@
 FROM ubuntu:trusty
 
+ARG apt_repository="deb [arch=amd64] http://apt-mk.mirantis.com/trusty/ nightly extra"
+ARG apt_key_url="http://apt-mk.mirantis.com/public.gpg"
+
 ## Common
 ENV DEBIAN_FRONTEND noninteractive
 RUN apt-get update && \
     apt-get install -y wget && \
-    echo "deb [arch=amd64] http://apt-mk.mirantis.com/trusty/ nightly extra" >> /etc/apt/sources.list.d/mirantis.list && \
-    wget -O - http://apt-mk.mirantis.com/public.gpg | apt-key add -
+    echo "$apt_repository" >> /etc/apt/sources.list.d/mirantis.list && \
+    wget -O - $apt_key_url | apt-key add -
 
 RUN apt-get update && apt-get install -y python-flask-hello