more docker work

Dockerfile

@@ -1,14 +1,17 @@
 FROM ruby:2.4.2-alpine
-MAINTAINER Rapid7
+LABEL maintainer="Rapid7"
 
 ARG BUNDLER_ARGS="--jobs=8 --without development test coverage"
 ENV APP_HOME /usr/src/metasploit-framework/
 ENV MSF_USER msf
 ENV NMAP_PRIVILEGED=""
+ENV BUNDLE_IGNORE_MESSAGES="true"
 WORKDIR $APP_HOME
 
-COPY Gemfile* m* Rakefile $APP_HOME
-COPY lib $APP_HOME/lib
+COPY Gemfile* metasploit-framework.gemspec Rakefile $APP_HOME
+COPY lib/metasploit/framework/version.rb $APP_HOME/lib/metasploit/framework/version.rb
+COPY lib/metasploit/framework/rails_version_constraint.rb $APP_HOME/lib/metasploit/framework/rails_version_constraint.rb
+COPY lib/msf/util/helper.rb $APP_HOME/lib/msf/util/helper.rb
 
 RUN apk update && \
     apk add \
@@ -36,8 +39,7 @@ RUN apk update && \
       ncurses-dev \
       git \
     && echo "gem: --no-ri --no-rdoc" > /etc/gemrc \
-    # this currently fails: https://github.com/rubygems/rubygems/issues/2064
-    # && gem update --system \
+    && gem update --system \
     && gem install bundler \
     && bundle install --system $BUNDLER_ARGS \
     && apk del .ruby-builddeps \
@@ -46,7 +48,7 @@ RUN apk update && \
 RUN adduser -g msfconsole -D $MSF_USER
 
 RUN /usr/sbin/setcap cap_net_raw,cap_net_bind_service=+eip $(which ruby)
-RUN /usr/sbin/setcap cap_net_raw,cap_net_bind_service=+eip /usr/bin/nmap
+RUN /usr/sbin/setcap cap_net_raw,cap_net_bind_service=+eip $(which nmap)
 
 USER $MSF_USER