Update

Dockerfile

-# define builder target
+# Define builder target
 FROM debian:stable-slim as builder
 
 # Environment PATH HOME HOSTNAME
 # ENV PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 # ENV HOME /
 
-# Prepare build dependencies and clean up
+# Build deps and clean up
 ARG BUILD_DEPS
-RUN apt-get -q update && \
-    DEBIAN_FRONTEND=noninteractive apt-get -qy upgrade && \
-    DEBIAN_FRONTEND=noninteractive apt-get -qy install --no-install-recommends ${BUILD_DEPS} \
+RUN export DEBIAN_FRONTEND=noninteractive && \
+    apt-get -qy update && \
+    apt-get -qy upgrade && \
+    apt-get -qy install --no-install-recommends ${BUILD_DEPS} \
         build-essential ca-certificates curl git iproute2 wget && \
     apt-get clean && rm -rf /var/lib/apt/lists/*