Use a single RUN command in dockerfile

Author: zacblazic

Dockerfile

@@ -1,23 +1,21 @@
 FROM debian:stretch-slim
 
-RUN apt-get update -y && \
-    apt-get install --no-install-recommends -y \
-      ca-certificates wget && \
-    rm -rf /tmp/* /var/{cache,log,tmp} /var/lib/{apt,dpkg,cache,log}
-
 ARG OAUTH2_PROXY_VERSION="2.2"
 ARG OAUTH2_PROXY_GOLANG_VERSION="1.8.1"
 ARG OAUTH2_PROXY_PKG_VERSION="2.2.0"
 ARG OAUTH2_PROXY_PKG="oauth2_proxy-${OAUTH2_PROXY_PKG_VERSION}.linux-amd64.go${OAUTH2_PROXY_GOLANG_VERSION}"
 ARG OAUTH2_PROXY_SHA="1c16698ed0c85aa47aeb80e608f723835d9d1a8b98bd9ae36a514826b3acce56"
 
-RUN mkdir -p /var/tmp/oauth2_proxy && \
+RUN apt-get update -y && \
+    apt-get install --no-install-recommends -y \
+      ca-certificates wget && \
+    mkdir -p /var/tmp/oauth2_proxy && \
     cd /var/tmp/oauth2_proxy && \
     wget --progress=dot:mega https://github.com/bitly/oauth2_proxy/releases/download/v${OAUTH2_PROXY_VERSION}/${OAUTH2_PROXY_PKG}.tar.gz && \
     echo "${OAUTH2_PROXY_SHA} *${OAUTH2_PROXY_PKG}.tar.gz" | sha256sum -c - && \
     tar xvf ${OAUTH2_PROXY_PKG}.tar.gz && \
-    cp /var/tmp/oauth2_proxy/${OAUTH2_PROXY_PKG}/oauth2_proxy /bin/ &&
-    rm -rf /var/tmp/oauth2_proxy
+    cp /var/tmp/oauth2_proxy/${OAUTH2_PROXY_PKG}/oauth2_proxy /bin/ && \
+    rm -rf /tmp/* /var/{cache,log,tmp} /var/lib/{apt,dpkg,cache,log}
 
 EXPOSE 4180