cache Docker builds

docker/node/Dockerfile

@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1.4
 FROM ubuntu:22.04 AS builder
 
 ARG COMPILER=gcc
@@ -7,43 +8,50 @@ ARG NANO_NETWORK=live
 COPY ./ci/prepare/linux /tmp/prepare
 RUN /tmp/prepare/prepare.sh
 
-COPY ./ /tmp/src
-WORKDIR /tmp/src
-
-# Define ARGs for ci/build-node.sh
+# Define build arguments
 ARG BUILD_TYPE=RelWithDebInfo
 ARG NANO_TEST=OFF
-ARG NANO_TRACING=OFF
+ARG NANO_TRACING=ON
 ARG COVERAGE=OFF
 ARG CMAKE_SANITIZER=""
 ARG CI_TAG=DEV_BUILD
 ARG CI_VERSION_PRE_RELEASE=OFF
 ARG SANITIZER
 
-# Build node
-RUN ci/build-node.sh
+# Copy source and set workdir
+COPY ./ /tmp/src
+WORKDIR /tmp/src
+
+# Use cache mount for build directory and copy outputs to a permanent location
+RUN --mount=type=cache,target=/tmp/src/build,id=nano_build,sharing=locked \
+    mkdir -p build && \
+    ci/build-node.sh && \
+    mkdir -p /tmp/build_output && \
+    cp build/nano_node build/nano_rpc /tmp/build_output/
+
 RUN echo ${NANO_NETWORK} >/etc/nano-network
 
 FROM ubuntu:22.04
 
 RUN groupadd --gid 1000 nanocurrency && \
     useradd --uid 1000 --gid nanocurrency --shell /bin/bash --create-home nanocurrency
 
-COPY --from=builder /tmp/src/build/nano_node /usr/bin
-COPY --from=builder /tmp/src/build/nano_rpc /usr/bin
+# Copy from the permanent location instead of the cache mount
+COPY --from=builder /tmp/build_output/nano_node /usr/bin
+COPY --from=builder /tmp/build_output/nano_rpc /usr/bin
 COPY --from=builder /tmp/src/api/ /usr/bin/api/
 COPY --from=builder /etc/nano-network /etc
-
 COPY docker/node/entry.sh /usr/bin/entry.sh
 COPY docker/node/config /usr/share/nano/config
-RUN chmod +x /usr/bin/entry.sh
-RUN ln -s /usr/bin/nano_node /usr/bin/rai_node
-RUN ldconfig
+
+RUN chmod +x /usr/bin/entry.sh && \
+    ln -s /usr/bin/nano_node /usr/bin/rai_node && \
+    ldconfig
 
 WORKDIR /root
 USER root
-
 ENV PATH="${PATH}:/usr/bin"
+
 ENTRYPOINT ["/usr/bin/entry.sh"]
 CMD ["nano_node", "daemon", "-l"]