Apply hadolint recommendations
FROM rust:1.42.0-slim-buster
-RUN apt-get update
-RUN apt-get install -y clang cmake
-RUN apt-get install -y libsnappy-dev
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends clang=1:7.* cmake=3.* \
+ libsnappy-dev=1.* \
+ && apt-get clean \
+ && rm -rf /var/lib/apt/lists/*
RUN adduser --disabled-login --system --shell /bin/false --uid 1000 user
