Bug 1858: Adding APT proxy

Adds apt proxy to build scripts and dockerfiles.  Backward compatible
change and proxy will not be used unless environment variable
is supplied to docker build command.

Fixes bug 1858

Change-Id: Ibd25bd1c145b8d43eeb85c5c952aec30ebcce1fc
Signed-off-by: beierlm <mark.beierl@canonical.com>
diff --git a/docker/NG-UI/Dockerfile b/docker/NG-UI/Dockerfile
index 53ec2a9..8350034 100644
--- a/docker/NG-UI/Dockerfile
+++ b/docker/NG-UI/Dockerfile
@@ -1,4 +1,5 @@
-# Copyright 2020 ETSI
+#######################################################################################
+# Copyright ETSI Contributors and Others.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -12,9 +13,16 @@
 # implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+#######################################################################################
 
 FROM ubuntu:18.04 AS BUILD
 
+ARG APT_PROXY
+RUN if [ ! -z $APT_PROXY ] ; then \
+    echo "Acquire::http::Proxy \"$APT_PROXY\";" > /etc/apt/apt.conf.d/proxy.conf ;\
+    echo "Acquire::https::Proxy \"$APT_PROXY\";" >> /etc/apt/apt.conf.d/proxy.conf ;\
+    fi
+
 RUN DEBIAN_FRONTEND=noninteractive apt-get --yes update && \
     DEBIAN_FRONTEND=noninteractive apt-get --yes install \
     apt-transport-https=1.6.* \