Dockerfile

Description:

• https://docs.docker.com/engine/reference/builder/
• Works layer by layer, data are used in the next layer
• Start from the least likely to be changed first
• Next update uses a last update and add the differences as a layer
  • much smaller file size

FROM

• Base image, from docker hub
• A valid Dockerfile must start with a FROM instruction.
• The image can be any valid image.
  • FROM python:3.7

COPY

• Copy individual file from source code to image or COPY . .

WORKDIR

• Equivalent to cd
• The WORKDIR instruction sets the working directory for any RUN, CMD, ENTRYPOINT, COPY and ADDinstructions that follow it in the Dockerfile.
• If the WORKDIR doesn’t exist, it will be created even if it’s not used in any subsequent Dockerfile instruction.
  • WORKDIR /app

RUN

• Run in shell

ENV

• Environment variable

CMD

• Last command
• Use it for starting the app