ruby: source .bashrc before installing gems

Author: mickamy

docker/app/ruby/Dockerfile

@@ -16,7 +16,10 @@ COPY --chown=ishocon:ishocon webapp/ /home/ishocon/webapp
 WORKDIR /home/ishocon
 
 # ライブラリのインストール
-RUN ["/bin/bash", "-lc", "cd /home/ishocon/webapp/ruby && gem install bundler && bundle install"]
+RUN bash -c "source ~/.bashrc" && \
+    cd /home/ishocon/webapp/ruby && \
+    gem install bundler -v "1.16.1" &&  \
+    bundle install
 
 COPY run.sh /home/ishocon/run.sh