Experiments

1 min read

Dockerfile

FROM

  • Base docker image
FROM eclipse-temurin:17

ADD and COPY

  • COPY: copy files from the system to the container
  • ADD: same as COPY but also can unzip archives and accept urls
COPY <system-src-path> <docker-dest-path>
ADD <system-src-path> <docker-dest-path>

RUN

  • Execute command
# Shell form
RUN npm start
 
# Exec form, preferred
RUN ["npm", "start"]

EXPOSE

  • Expose port
EXPOSE 8090

WORKDIR

  • Working Directory
WORKDIR /tmp

ENV

  • Set environment variables:
ENV AXDIR /fitnesse
ENV SPRING_PROFILES_ACTIVE=prod

ARG

  • defines build time environment variables
  • Running containers do not have access to the variables
  • should not be used for sensitive data since docker history can reveal the variables
ARG variable=value

CMD and ENTRYPOINT

  • Both accepts shell and exec forms
  • CMD: runtime command
CMD ["echo", "hello"]
  • ENTRYPOINT: runtime command prefix
    • In the following example, you can run: docker run <image> hello to execute echo hello
ENTRYPOINT ["echo"]