Move apk add and del into same layer

Prevents bloating of final image

Author: jeffb4

Dockerfile

@@ -4,9 +4,11 @@ FROM rpardini/nginx-proxy-connect-stable-alpine:nginx-1.14.0-alpine-3.8
 
 # Add openssl, bash and ca-certificates, then clean apk cache -- yeah complain all you want.
 # Also added deps for mitmproxy.
-RUN apk add --update openssl bash ca-certificates su-exec git g++ libffi libffi-dev libstdc++ openssl openssl-dev python3 python3-dev
-RUN LDFLAGS=-L/lib pip3 install mitmproxy
-RUN apk del --purge git g++ libffi-dev openssl-dev python3-dev && rm -rf /var/cache/apk/* && rm -rf ~/.cache/pip
+RUN apk add --update openssl bash ca-certificates su-exec git g++ libffi libffi-dev libstdc++ openssl openssl-dev python3 python3-dev \
+ && LDFLAGS=-L/lib pip3 install mitmproxy \
+ && apk del --purge git g++ libffi-dev openssl-dev python3-dev \
+ && rm -rf /var/cache/apk/* \
+ && rm -rf ~/.cache/pip
 
 # Required for mitmproxy
 ENV LANG=en_US.UTF-8