Dockerfile

• Dockerfiles are instructions on how to build an image
• The file contains all commands used to start a container:
  • Docker image consists of read-only layers
  • Each layer represents a Dockerfile instruction
  • Layers are stacked
  • Each layer is a delta of the changes from the previous layer
  • Images are built using the docker image build command (with necessary flags)
• General guidelines:
  • Keep containers as ephemeral as possible
  • Avoid including unnecessary files
    • Use .dockerignore
  • Use multi-stage builds to reduce the size of image size
    • Dont include unnecessary packages
    • Minimize the number of layers
  • Decouple applications
  • Sort multi-line arguments
  • Leverage the build cache