1. Reduce size of the image
RUN apt-get clean && rm -f /var/lib/apt/lists/*_*
2. Combine update, install and clean:
RUN apt-get update -y \
&& apt-get install -y -q package-name \
&& apt-get clean \
&& rm -f /var/lib/apt/lists/*_*
3. Use a separate build stage
FROM base-image AS builder
COPY . /app
RUN apt-get install build-essential \
&& bundle install --deployment
FROM base-image
COPY --from=builder /app /app
4. Set the system locale
RUN echo "en_US.UTF-8 UTF-8" > /etc/locale.gen \
&& locale-gen en_US.UTF-8
ENV LANG en_US.UTF-8
ENV LANGUAGE en_US:en
5. Create an unprivileged user
# After build
RUN adduser -s /bin/sh -u 1001 -G root \
-h /app -S -D rails \
&& chown -R rails /app
USER rails
6. Prefer exec form for CMD
CMD ["bundle", "exec", "rails", "s"]
7. Specify resource constraints in production
requests:
memory: "100Mi"
cpu: 0.5
limits:
memory: "200Mi"
cpu: 1.0
8. Log to STDOUT or an external agent
ENV RAILS_LOG_STDOUT=true
