Docker Images

How to create my own image?

Order

1. OS - Ubuntu
2. Update apt repo
3. Install dependencies using apt
4. Install Python dependencies using pip
5. Copy source code to /opt folder
6. Run the web server using “flask” command

Dockerfile

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FROM Ubuntu

RUN apt-get update && apt-get -y install python

RUN pip install flask flask-mysql

COPY . /opt/source-code

ENTRYPOINT FLASK_APP=/opt/source-code/app.py flask run

• INSTRUCTION ARGUMENT

Build

• docker build . -f Dockerfile -t <image name>

Push

• docker push <image name>

Layered architecture

• each layer only store the changes from the previous layer
• docker history <image name>

Environment Variables

• -e
  • docker run -e <KEY>=<value> <image name>

Inspect Environment Variable

• docker inspect <container name | id>

Command vs Entrypoint

설명

Command

• CMD
• instruction the command line parameters passed will get replaced entirely.

Entrypoint

• ENTRYPOINT
• command line parameters will get appended.
• if parameter is not given, it will get error that the operand is missing
  • How to give and default value for entrypoint?

    1 2	ENTRYPOINT ["command"] CMD ["param1"]

• how to override entrypoint?
  • docker run --entrypoint <executable> <image-name> <param>

명령어

• CMD
  • CMD command param1
  • CMD ["command", "param1"]
• ENTRYPOINT
  • ENTRYPOINT ["command"]