fix dockerfile

Dockerfile

@@ -1,21 +1,28 @@
 FROM ruby:2.4
 
-WORKDIR /usr/src/app/
-
 # see http://stackoverflow.com/questions/38453963/gitlab-ci-setup-error-could-not-find-a-javascript-runtime
 RUN apt-get update && apt-get install nodejs -y
 
-# set locale
-RUN apt-get install -y locales
-RUN dpkg-reconfigure locales && \
-  locale-gen C.UTF-8 && \
-  /usr/sbin/update-locale LANG=C.UTF-8
-RUN echo 'en_US.UTF-8 UTF-8' >> /etc/locale.gen && \
-  locale-gen
-ENV LC_ALL C.UTF-8
-ENV LANG en_US.UTF-8
-ENV LANGUAGE en_US.UTF-8
+# throw errors if Gemfile has been modified since Gemfile.lock
+RUN bundle config --global frozen 1
+
+ENV LANG C.UTF-8
+
+WORKDIR /usr/src/app
 
-# install gems
 COPY Gemfile /usr/src/app/
-RUN bundle install
+COPY Gemfile.lock /usr/src/app/
+RUN bundle install
+
+COPY . /usr/src/app
+
+# set locale
+# RUN apt-get install -y locales
+# RUN dpkg-reconfigure locales && \
+#   locale-gen C.UTF-8 && \
+#   /usr/sbin/update-locale LANG=C.UTF-8
+# RUN echo 'en_US.UTF-8 UTF-8' >> /etc/locale.gen && \
+#   locale-gen
+# ENV LC_ALL C.UTF-8
+# ENV LANG en_US.UTF-8
+# ENV LANGUAGE en_US.UTF-8