this might work better

automation/Dockerfile

@@ -6,7 +6,7 @@ RUN apt-get update
 RUN apt-get --yes upgrade
 # tzdata is a dependency, won't install otherwise
 ARG DEBIAN_FRONTEND=noninteractive
-RUN apt-get --yes install rsync
+RUN apt-get --yes install rsync curl
 
 # set CROSS_CONTAINER_IN_CONTAINER to inform `cross` that it is executed from within a container
 ENV CROSS_CONTAINER_IN_CONTAINER=true
@@ -15,6 +15,8 @@ RUN rustup install nightly && \
     rustup target add thumbv7em-none-eabihf armv7-unknown-linux-gnueabihf && \
     rustup component add rustfmt clippy llvm-tools-preview
 
+RUN curl -sSL https://github.com/mozilla/grcov/releases/download/v0.8.19/grcov-x86_64-unknown-linux-gnu.tar.bz2 | tar -x --directory /usr/local/bin
+
 # SSH stuff to allow deployment to doc server
 RUN adduser --uid 114 jenkins