fix ruby distrib tests

tools/dockerfile/distribtest/ruby_ubuntu1604_x64/Dockerfile

@@ -14,6 +14,22 @@
 
 FROM ubuntu:16.04
 
-RUN apt-get update -y && apt-get install -y ruby-full
+# Install Git and basic packages.
+RUN apt-get update -y && apt-get install -y \
+  curl \
+  gcc && apt-get clean
 
-RUN gem install bundler
+#==================
+# Ruby dependencies
+
+# Install rvm
+RUN gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB
+RUN \curl -sSL https://get.rvm.io | bash -s stable
+
+# Install Ruby 2.4
+RUN /bin/bash -l -c "rvm install ruby-2.4.9"
+RUN /bin/bash -l -c "rvm use --default ruby-2.4.9"
+RUN /bin/bash -l -c "echo 'gem: --no-document' > ~/.gemrc"
+RUN /bin/bash -l -c "echo 'export PATH=/usr/local/rvm/bin:$PATH' >> ~/.bashrc"
+RUN /bin/bash -l -c "echo 'rvm --default use ruby-2.4.9' >> ~/.bashrc"
+RUN /bin/bash -l -c "gem install bundler -v 1.17.3 --no-document"