Docker updates

Dockerfile

@@ -1,23 +1,54 @@
-FROM ruby:2.6.10-slim
+FROM ruby:2.6.10-slim as base
 
-LABEL maintainer Travis CI GmbH <[email protected]>
-
-# packages required for bundle install
-RUN ( \
-   apt-get update ; \
-   apt-get install -y --no-install-recommends git make gcc g++ \
-   && rm -rf /var/lib/apt/lists/* \
-)
+# upgrade
+RUN apt-get update > /dev/null 2>&1 && \
+    apt-get upgrade -y > /dev/null 2>&1 && \
+    rm -rf /var/lib/apt/lists/*
 
-# throw errors if Gemfile has been modified since Gemfile.lock
-RUN bundle config --global frozen 1;
-RUN mkdir -p /app
+# Set app workdir
 WORKDIR /app
 
-# Copy app files into app folder
-COPY . /app
+# Upgrade rubygems
+RUN gem update --system > /dev/null 2>&1
+
+# Gem config
+RUN echo "gem: --no-document" >> ~/.gemrc
+
+# Bundle config
+RUN bundle config set --global no-cache 'true' && \
+    bundle config set --global frozen 'true' && \
+    bundle config set --global deployment 'true' && \
+    bundle config set --global without 'development test' && \
+    bundle config set --global clean 'true' && \
+    bundle config set --global jobs `expr $(cat /proc/cpuinfo | grep -c 'cpu cores')` && \
+    bundle config set --global retry 3
+
+FROM base as builder
+
+# packages required
+RUN apt-get update > /dev/null 2>&1 && \
+    apt-get install -y --no-install-recommends git make gcc g++ > /dev/null 2>&1 && \
+    rm -rf /var/lib/apt/lists/*
+
+# Copy .ruby-version and .gemspec into container
+COPY .ruby-version travis-yml.gemspec ./
+COPY ./lib/travis/yml/version.rb ./lib/travis/yml/version.rb
+
+# Copy gemfiles into container
+COPY Gemfile Gemfile.lock ./
+
+# Install gems
+RUN bundle install
+
+
+FROM base
+
+LABEL maintainer Travis CI GmbH <[email protected]>
+
+# Copy gems from builder
+COPY --from=builder /usr/local/bundle /usr/local/bundle
 
-RUN gem install bundler -v '2.0.1'
-RUN bundle install --deployment --without development test --clean
+# Copy app files
+COPY . ./
 
-CMD bundle exec puma -C lib/travis/yml/web/puma.rb
+CMD ["bundle", "exec", "puma", "-C", "lib/travis/yml/web/puma.rb"]