Dockerfile instructions
CMD and ENTRYPOINT
- These instructions will be executed when we are staring the container using the image
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If neither of them are specified, then base images CMD or ENTRYPOINT wll be used.
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In the following case, then docker will be excute NGINX CMD or Entrypoint
FROM nginx
RUN touch 1.txt
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Your container will be in running state as long the CMD or entrypoint is running
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CMD can be overriten
docker run -d --name test3 test:2 sleep 10s
sleep 10s will overrite CMD
- If Entrypoint instruction exists then the start command would be ENTRYPOINT + CMD
FROM alpine
ENTRYPOINT ["sleep"]
CMD ["20s"]
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ENTRYPOINT can also be changed by using
--entrypoint
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ideally your entrypoint + cmd should be executing as long as your application runs
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IF your container has server like nginx, apache, tomcat etc dont write entrypoint
EXPOSE
- This tells docker engine on which port your applicaion is running
LABEL
