base: speed up local rebuilds.

Using ccache can speed up local rebuilds even when the container layer
cache is invalidated, which is easy to happen. It also requires a less
complicated and less fragile setup than distcc (though distcc will
always make for faster first builds).

install_epics.sh still supports ccache-less setups, should that be
required.

On my machine, building an image with ccache for the first time took
~15m. Rebuilding it after invalidating the layer cache took only 3m36s.
The output of 'ccache -s' is reproduced below:

    Cacheable calls:   3858 / 8743 (44.13%)
      Hits:            1923 / 3858 (49.84%)
        Direct:        1822 / 1923 (94.75%)
        Preprocessed:   101 / 1923 ( 5.25%)
      Misses:          1935 / 3858 (50.16%)
    Uncacheable calls: 4885 / 8743 (55.87%)
    Local storage:
      Cache size (GB): 0.18 / 5.00 ( 3.70%)

It is not clear why the cache hits were below 50%, but it was still
enough to make a big difference in build times.

This was based on StackOverflow [1].

[1] https://stackoverflow.com/a/56833198

Author: ericonr

base/Dockerfile

@@ -5,6 +5,7 @@ FROM debian:${DEBIAN_VERSION}
 ARG JOBS
 
 ENV DEBIAN_FRONTEND=noninteractive
+ARG CCACHE_DIR=/ccache
 
 # Disable APT sandbox so that single UID restriction is satisfied in systems
 # without subuid and subgid configured.
@@ -13,6 +14,7 @@ RUN echo 'APT::Sandbox::User "root";' > /etc/apt/apt.conf.d/90-disable-sandbox.c
 RUN apt update -y && \
     apt install -y --no-install-recommends \
         build-essential \
+        ccache \
         git \
         libaravis-dev \
         libevent-dev \
@@ -32,7 +34,8 @@ RUN apt update -y && \
         python3-dev \
         cython3 \
         python3-numpy \
-        ca-certificates
+        ca-certificates && \
+    for p in gcc g++; do ln -vs /usr/bin/ccache /usr/local/bin/$p; done
 
 COPY lnls-get-n-unpack.sh /usr/local/bin/lnls-get-n-unpack
 
@@ -49,24 +52,26 @@ WORKDIR /opt/epics
 
 COPY epics-base-static-linking.patch $EPICS_IN_DOCKER
 COPY epics_versions.sh install_epics.sh $EPICS_IN_DOCKER
-RUN $EPICS_IN_DOCKER/install_epics.sh
+RUN --mount=type=cache,target=/ccache/ USE_CCACHE=1 $EPICS_IN_DOCKER/install_epics.sh
 
 WORKDIR ${EPICS_MODULES_PATH}
 
 COPY backport-ipmicomm.patch ipmicomm.patch caputlog-waveform-fix.patch $EPICS_IN_DOCKER
 COPY modules_versions.sh install_modules.sh $EPICS_IN_DOCKER
-RUN NEEDS_TIRPC=YES $EPICS_IN_DOCKER/install_modules.sh
+RUN --mount=type=cache,target=/ccache/ NEEDS_TIRPC=YES $EPICS_IN_DOCKER/install_modules.sh
 
 COPY backport-adsupport-nanohttp.patch $EPICS_IN_DOCKER
 COPY area_detector_versions.sh install_area_detector.sh $EPICS_IN_DOCKER
-RUN $EPICS_IN_DOCKER/install_area_detector.sh
+RUN --mount=type=cache,target=/ccache/ $EPICS_IN_DOCKER/install_area_detector.sh
 
 COPY motor_versions.sh install_motor.sh $EPICS_IN_DOCKER
-RUN $EPICS_IN_DOCKER/install_motor.sh
+RUN --mount=type=cache,target=/ccache/ $EPICS_IN_DOCKER/install_motor.sh
 
 ARG DEBIAN_VERSION
 COPY opcua_versions.sh install_opcua.sh $EPICS_IN_DOCKER
-RUN $EPICS_IN_DOCKER/install_opcua.sh
+RUN --mount=type=cache,target=/ccache/ $EPICS_IN_DOCKER/install_opcua.sh
+
+RUN --mount=type=cache,target=/ccache/ ccache -s
 
 COPY lnls-prune-artifacts.sh /usr/local/bin/lnls-prune-artifacts
 COPY lnls-run.sh /usr/local/bin/lnls-run

base/install_epics.sh

@@ -14,4 +14,8 @@ if [ -n "$COMMANDLINE_LIBRARY" ]; then
     echo "COMMANDLINE_LIBRARY = $COMMANDLINE_LIBRARY" > ${EPICS_BASE_PATH}/configure/CONFIG_SITE.local
 fi
 
+if [ "$USE_CCACHE" = 1 ]; then
+    printf "CC=/usr/local/bin/gcc\nCCC=/usr/local/bin/g++\n" >> ${EPICS_BASE_PATH}/configure/CONFIG.gnuCommon
+fi
+
 install_module base EPICS_BASE

base/musl/Dockerfile

@@ -4,8 +4,11 @@ FROM alpine:$ALPINE_VERSION
 
 ARG JOBS
 
+ARG CCACHE_DIR=/ccache
+
 RUN apk add --no-cache \
     bash \
+    ccache \
     git \
     g++ \
     libevent-dev \
@@ -32,7 +35,8 @@ RUN apk add --no-cache \
     python3-dev \
     py3-setuptools \
     cython \
-    py3-numpy-dev
+    py3-numpy-dev && \
+    for p in gcc g++; do ln -vs /usr/bin/ccache /usr/local/bin/$p; done
 
 COPY lnls-get-n-unpack.sh /usr/local/bin/lnls-get-n-unpack
 COPY lnls-run.sh /usr/local/bin/lnls-run
@@ -50,12 +54,14 @@ WORKDIR /opt/epics
 
 COPY epics-base-static-linking.patch $EPICS_IN_DOCKER
 COPY epics_versions.sh install_epics.sh $EPICS_IN_DOCKER
-RUN COMMANDLINE_LIBRARY=READLINE_NCURSES $EPICS_IN_DOCKER/install_epics.sh
+RUN --mount=type=cache,target=/ccache/ USE_CCACHE=1 COMMANDLINE_LIBRARY=READLINE_NCURSES $EPICS_IN_DOCKER/install_epics.sh
 
 WORKDIR ${EPICS_MODULES_PATH}
 
 COPY backport-ipmicomm.patch ipmicomm.patch caputlog-waveform-fix.patch $EPICS_IN_DOCKER
 COPY modules_versions.sh install_modules.sh $EPICS_IN_DOCKER
-RUN NEEDS_TIRPC=YES $EPICS_IN_DOCKER/install_modules.sh
+RUN --mount=type=cache,target=/ccache/ NEEDS_TIRPC=YES $EPICS_IN_DOCKER/install_modules.sh
+
+RUN --mount=type=cache,target=/ccache/ ccache -s
 
 COPY lnls-build-static-ioc.sh /usr/local/bin/lnls-build-static-ioc