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Evaluator Images

Kelvin uses a set of Docker images to evaluate student submissions safely and consistently. These images are built in a hierarchical manner to minimize duplication and ensure consistency.

Image Structure​

All evaluator images are located in evaluator/images/. The structure is designed to allow dependency inheritance between images.

  • base: The base image (kelvin/base) that all other images typically inherit from. It contains common tools and configurations (like locale settings, common libraries).
  • Language-specific images: Images like gcc, java, pythonrun, etc. These inherit from kelvin/base (or other kelvin images) and install specific compilers or interpreters.

Dependency Management​

The build system automatically detects dependencies between images by parsing their Dockerfile FROM instructions. For example, if evaluator/images/gcc/Dockerfile contains FROM kelvin/base, the build system ensures kelvin/base is built before kelvin/gcc.

Building Images​

To build the images, use the provided build.py script located in evaluator/images/.

cd evaluator/images
uv run build.py

Build Options​

  • --dry-run: Print the docker build commands that would be executed without running them.
uv run build.py --dry-run

Adding a New Runtime Environment​

To add support for a new language or tool:

  1. Create a new directory in evaluator/images/ (e.g., evaluator/images/rust).

  2. Create a Dockerfile in that directory.

  3. Inherit from kelvin/base (or another appropriate parent).

    Example Dockerfile:

    FROM kelvin/base

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

  4. Run the build script. It will automatically detect the new image and its dependency.

uv run build.py

The image will be named kelvin/<directory_name> (e.g., kelvin/rust).