rules:
  - id: remove-package-lists
    patterns:
      - pattern-not-inside: RUN ... rm -rf /var/lib/apt/lists/*
      - pattern: RUN apt-get update ...
      - pattern: apt-get update
    message: >-
      The package lists were not deleted after running 'apt-get update', which
      increases the size of the image.
      Remove the package lists by appending '&& rm -rf /var/lib/apt/lists/*' at the
      end
      of apt-get command chain.
    severity: WARNING
    languages: [dockerfile]
    metadata:
      source-rule-url: https://github.com/hadolint/hadolint/wiki/DL3009
      references:
        - https://github.com/hadolint/hadolint/wiki/DL3009
      category: best-practice
      technology:
        - dockerfile