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How to Dockerize your project?

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Creating a Dockerfile

Usual steps of creating a Dockerfile of your application:

  1. Specify Base Image
  2. Specify any environment variables
  3. Specify commands to run on the top of OS layer such as:
    • downloading or updating dependencies
    • add groups or users to run process instead of root
  4. Copy the application files into the image.
  5. Specify which port(s) for container to listen
  6. Specify the command to start the application
Dockerfile InstructionsArguments
FROMBase Image or other Container Image
RUN1. Passing commands (runs in shell)
2. Passing exec form: [“executable”, “p1”, “p2”]
Execute command in a new layer.

Examples:
– Updating dependencies
COPYCOPY is preferred to ADD as we know clearly that COPY will just copy files from local directory. ADD is useful if you wanna copy the content in a tar file.
ENTRYPOINTDefine the command that will always be executed when the container starts.

By default, Docker is using  /bin/sh -c as the entrypoint.
CMDDefine the arguments that will be appended to the ENTRYPOINT
WORKDIRDefine where your commands should run. Saves the trouble of running to many cd .....
EXPOSEDefine the ports that a container listens.
ENVSetting environment variables that can be used in other instructions such as RUN
FROM node:12-alpine
RUN apk add --no-cache python2 g++ make
EXPOSE 9091
WORKDIR /app
COPY . .
RUN yarn install --production
CMD ["node", "src/index.js"]

References:

Running a container

Make sure the port publish setting (-p) is positioned before the image tag so that it can override the image default settings.

https://stackoverflow.com/questions/66316400/cannot-reach-docker-container-port-not-bound
docker run -p 9091:9091 -t spring-boot-docker

References:

Published inContainerDocker

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