Reduce image size

Dockerfile

@@ -1,16 +1,22 @@
-FROM ruby:2.6.6-alpine3.13
+FROM ruby:2.6.6-alpine3.13 AS build
 
 RUN apk update && apk upgrade && \
-    apk add --no-cache bash git openssh build-base gcc wget git
+    apk add --no-cache git openssh build-base gcc wget git
 
 RUN gem install bundler -v 2.3.6
 
-WORKDIR /opt/representer
-
 COPY Gemfile Gemfile.lock .
 
 RUN bundle install
 
+FROM ruby:2.6.6-alpine3.13 AS runtime
+
+RUN apk add --no-cache bash
+
+WORKDIR /opt/representer
+
+COPY --from=build /usr/local/bundle /usr/local/bundle
+
 COPY . .
 
 ENTRYPOINT ["sh", "/opt/representer/bin/run.sh"]