pre-install nokogiri
@@ -13,3 +13,6 @@ RUN curl -L https://bitbucket.org/ariya/phantomjs/downloads/phantomjs-2.1.1-linu
RUN apt-get update && apt-get -y install build-essential
ADD go*.tar.gz /usr/local
ENV PATH $PATH:/usr/local/go/bin
+
+# pre-install nokogiri to shorten build time
+RUN gem install nokogiri
