solved caching for building a custom package

docker/custom_package/Dockerfile

@@ -1,21 +1,39 @@
-FROM ctumrs/mrs_uav_system:robofly
+ARG WORKSPACE_PATH
+ARG BASE_IMAGE=ctumrs/mrs_uav_system:latest
 
-ARG WORKSPACE_PATH="/etc/robofly/catkin_workspace"
+#############################################################################
 
-# create catkin workspace
-RUN mkdir -p ${WORKSPACE_PATH} && cd ${WORKSPACE_PATH} && rm -rf ./* && mkdir src
-RUN cd ${WORKSPACE_PATH} && catkin init
+# FIRST STAGE: BUILD THE WORKSPACE
+FROM $BASE_IMAGE AS stage_build
+
+ARG WORKSPACE_PATH
 
-# set workspace build profile
-RUN cd ${WORKSPACE_PATH} && catkin config --profile reldeb --cmake-args -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_EXPORT_COMPILE_COMMANDS=ON && catkin profile set reldeb && catkin config --extend /opt/ros/noetic
+COPY ./cache/${WORKSPACE_PATH}/ /${WORKSPACE_PATH}/
+
+# create catkin workspace
+RUN [ ! -e /${WORKSPACE_PATH}/.catkin_tools ] && cd /${WORKSPACE_PATH} && catkin init && catkin config --profile reldeb --cmake-args -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_EXPORT_COMPILE_COMMANDS=ON && catkin profile set reldeb && catkin config --extend /opt/ros/noetic || echo "[Docker]: catkin workspace already exists"
 
 # copy the sources from the local subfolder
-COPY src/ ${WORKSPACE_PATH}/src/
+COPY src/ /${WORKSPACE_PATH}/src/
+
+RUN cd /${WORKSPACE_PATH} && catkin build -s
+
+#############################################################################
+
+# SECOND STAGE: COPY THE WORKSPACE TO A BLANK APLINE IMAGE
+FROM alpine AS stage_cache_workspace
+
+ARG WORKSPACE_PATH
+
+COPY --from=stage_build /${WORKSPACE_PATH} /${WORKSPACE_PATH}
+
+#############################################################################
 
-RUN ls ${WORKSPACE_PATH}/src/
+# THIRD STAGE: copy the workspace to a final blank ROS-equipped base image
+FROM $BASE_IMAGE AS stage_finalization
 
-RUN cd ${WORKSPACE_PATH} && catkin build -s
+ARG WORKSPACE_PATH
 
-RUN mkdir -p /etc/robofly/ws && cp -r ${WORKSPACE_PATH}/* /etc/robofly/ws/
+COPY --from=stage_cache_workspace /${WORKSPACE_PATH} /${WORKSPACE_PATH}
 
 CMD ["bash"]

docker/custom_package/build.sh

@@ -1,8 +1,20 @@
 #!/bin/bash
 
 LOCAL_TAG=robofly:custom_package
-REGISTRY=fly4future
 
-docker build . --file Dockerfile --tag $REGISTRY/$LOCAL_TAG --no-cache --progress=plain
+ARCH=arm64
+# ARCH=amd64
 
-# docker push $REGISTRY/$LOCAL_TAG
+WORKSPACE_PATH=etc/catkin_workspace
+CACHE_PATH=cache
+
+# initialize the cache
+mkdir -p ./${CACHE_PATH}/${WORKSPACE_PATH}
+
+# this first build compiles the contents of "src" and storest the intermediate
+# catkin workspace in ./cache
+docker build . --target stage_cache_workspace --output ./${CACHE_PATH} --build-arg WORKSPACE_PATH=${WORKSPACE_PATH} --file Dockerfile --platform=linux/arm64
+
+# this second build takes the resulting workspace and storest in in a final image
+# that can be deployed to a drone
+docker build . --target stage_finalization --file Dockerfile --build-arg WORKSPACE_PATH=${WORKSPACE_PATH} --tag $LOCAL_TAG --platform=linux/arm64