Hi and welcome @syspulse! Appreciate this contribution, but I have to admit some noob-ism when it comes to docker. Can you describe a little bit what the repercussions of your changes are when it comes to the build process, the install process, etc?

I think the repercussion is the docker build: https://github.com/polynote/polynote/blob/master/.github/workflows/dist.yml
At the moment you only export SCALA_VERSION to build image. Because of possible permutations, I suggest to have SPARK_VERSION and Hadoop versions dependencies. When Spark migrates to Scala 2.13 or Dotty this should be easier to add support.
This is how dist.yml run would look like:

echo "${DOCKER_PASSWORD}" | docker login -u ${DOCKER_USERNAME} --password-stdin
export POLYNOTE_VERSION=${GITHUB_REF#refs/tags/}
export SCALA_VERSION="2.11"
docker build -t polynote-base:$POLYNOTE_VERSION-$SCALA_VERSION --build-arg POLYNOTE_VERSION=$POLYNOTE_VERSION --build-arg SCALA_VERSION=$SCALA_VERSION docker/base
docker tag polynote-base:${POLYNOTE_VERSION}-${SCALA_VERSION} polynote/polynote:${POLYNOTE_VERSION}-${SCALA_VERSION}
docker push polynote/polynote:${POLYNOTE_VERSION}-${SCALA_VERSION}

export SPARK_VERSION="2.4.7"
docker build -t polynote:$POLYNOTE_VERSION-scala$SCALA_VERSION-spark$SPARK_VERSION --build-arg SPARK_VERSION=$SPARK_VERSION --build-arg SCALA_VERSION=$SCALA_VERSION --build-arg POLYNOTE_VERSION=$POLYNOTE_VERSION --build-arg HADOOP_VERSION=2.7.7 --build-arg HADOOP_VERSION_MAJOR=2.7 docker/spark
docker tag polynote:$POLYNOTE_VERSION-scala$SCALA_VERSION-spark$SPARK_VERSION polynote/polynote:${POLYNOTE_VERSION}-scala${SCALA_VERSION}-spark$SPARK_VERSION
docker push polynote/polynote:${POLYNOTE_VERSION}-scala${SCALA_VERSION}-spark$SPARK_VERSION
docker tag polynote:$POLYNOTE_VERSION-scala$SCALA_VERSION-spark$SPARK_VERSION polynote/polynote:latest
docker push polynote/polynote:latest

export SCALA_VERSION="2.12"
docker build -t polynote-base:$POLYNOTE_VERSION-$SCALA_VERSION --build-arg POLYNOTE_VERSION=$POLYNOTE_VERSION --build-arg SCALA_VERSION=$SCALA_VERSION docker/base
docker tag polynote-base:${POLYNOTE_VERSION}-${SCALA_VERSION} polynote/polynote:${POLYNOTE_VERSION}-${SCALA_VERSION}
docker push polynote/polynote:${POLYNOTE_VERSION}-${SCALA_VERSION}

export SPARK_VERSION="2.4.7"
docker build -t polynote:$POLYNOTE_VERSION-scala$SCALA_VERSION-spark$SPARK_VERSION --build-arg SPARK_VERSION=$SPARK_VERSION --build-arg SCALA_VERSION=$SCALA_VERSION --build-arg POLYNOTE_VERSION=$POLYNOTE_VERSION --build-arg HADOOP_VERSION=2.7.7 --build-arg HADOOP_VERSION_MAJOR=2.7 docker/spark
docker tag polynote:$POLYNOTE_VERSION-scala$SCALA_VERSION-spark$SPARK_VERSION polynote/polynote:${POLYNOTE_VERSION}-scala${SCALA_VERSION}-spark$SPARK_VERSION
docker push polynote/polynote:${POLYNOTE_VERSION}-scala${SCALA_VERSION}-spark$SPARK_VERSION

export SPARK_VERSION="3.0.1"
docker build -t polynote:$POLYNOTE_VERSION-scala$SCALA_VERSION-spark$SPARK_VERSION --build-arg SPARK_VERSION=$SPARK_VERSION --build-arg SCALA_VERSION=$SCALA_VERSION --build-arg POLYNOTE_VERSION=$POLYNOTE_VERSION --build-arg HADOOP_VERSION=3.2.1 --build-arg HADOOP_VERSION_MAJOR=3.2 docker/spark
docker tag polynote:$POLYNOTE_VERSION-scala$SCALA_VERSION-spark$SPARK_VERSION polynote/polynote:${POLYNOTE_VERSION}-scala${SCALA_VERSION}-spark$SPARK_VERSION
docker push polynote/polynote:${POLYNOTE_VERSION}-scala${SCALA_VERSION}-spark$SPARK_VERSION