Use sccache with prepopulated compilation cache

Dockerfile

@@ -8,10 +8,24 @@ ARG CLR_URL=https://github.com/dhovart/${CLR_NAME}/releases/download/${CLR_VERSI
 ARG JQ_VERSION=1.6
 ARG JQ_URL=https://github.com/stedolan/jq/releases/download/jq-${JQ_VERSION}/jq-linux64
 
+ARG SC_VERSION=v0.2.15
+ARG SC_URL=https://github.com/mozilla/sccache/releases/download/${SC_VERSION}/sccache-${SC_VERSION}-x86_64-unknown-linux-musl.tar.gz
+
+ENV SCCACHE_DIR=/opt/compilation-cache
+ENV RUSTC_WRAPPER=/usr/local/bin/sccache
+
+# download sccache
+RUN curl -L -o sccache.tgz "${SC_URL}" \
+ && tar xvzf sccache.tgz --strip-components=1 \
+ && cp sccache ${RUSTC_WRAPPER} \
+ && chmod +x ${RUSTC_WRAPPER}
+RUN mkdir -p ${SCCACHE_DIR}
+
 RUN mkdir -p /rust-test-runner/src
 ENV wd /rust-test-runner
 WORKDIR ${wd}
 COPY Cargo.* ./
+
 # for caching, we want to download and build all the dependencies before copying
 # any of the real source files. We therefore build an empty dummy library,
 # then remove it.
@@ -26,7 +40,7 @@ COPY bin/generate-registry.sh ${wd}/bin/
 # download jq
 RUN curl -L -o /usr/local/bin/jq "${JQ_URL}" \
  && chmod +x /usr/local/bin/jq
-# retrieve cargo-local-registry
+# download cargo-local-registry
 RUN curl -L -o clr.tar.gz "${CLR_URL}" \
  && tar xvzf clr.tar.gz --strip-components=1 \
  && chmod +x cargo-local-registry \
@@ -35,15 +49,21 @@ RUN curl -L -o clr.tar.gz "${CLR_URL}" \
 WORKDIR /local-registry
 COPY local-registry/* ./
 RUN ${wd}/bin/generate-registry.sh
+# populate compilation cache
+RUN cargo build
 
 # As of Dec 2019, we need to use the nightly toolchain to get JSON test output
 FROM rustlang/rust:nightly AS test
+ENV SCCACHE_DIR=/opt/compilation-cache
+ENV RUSTC_WRAPPER=/usr/local/bin/sccache
+COPY --from=build ${RUSTC_WRAPPER} ${RUSTC_WRAPPER}
+COPY --from=build ${SCCACHE_DIR} ${SCCACHE_DIR}
 ENV wd /opt/test-runner
 RUN mkdir -p ${wd}/bin
 WORKDIR ${wd}
 COPY --from=build /rust-test-runner/target/release/transform-output bin
 COPY --from=build /usr/local/bin/jq /usr/local/bin
-# configure local-registry
+# configure local registry
 COPY --from=build /local-registry local-registry/
 RUN echo '[source.crates-io]\n\
 registry = "https://github.com/rust-lang/crates.io-index"\n\