set ccache

.ci/travis/linux/script.sh

@@ -23,7 +23,7 @@ if [[ $DOCKER_QGIS_IMAGE_PUSH =~ true ]]; then
   DIR=$(git rev-parse --show-toplevel)/.docker
   pushd ${DIR}
   echo "${bold}Building QGIS Docker image...${endbold}"
-  docker build -v /root/QGIS:/root/QGIS --cache-from "qgis/qgis:${DOCKER_TAG}" -t "qgis/qgis:${DOCKER_TAG}" -f qgis.dockerfile .
+  docker build --build-arg CACHE_DIR=/root/.ccache --cache-from "qgis/qgis:${DOCKER_TAG}" -t "qgis/qgis:${DOCKER_TAG}" -f qgis.dockerfile .
   if [[ $DOCKER_QGIS_IMAGE_PUSH =~ true ]]; then
     echo "${bold}Pushing image to docker hub...${endbold}"
     docker login -u="$DOCKER_USERNAME" -p="$DOCKER_PASSWORD"

.docker/qgis.dockerfile

@@ -2,7 +2,8 @@
 # CACHE_TAG is provided by Docker cloud
 # see https://docs.docker.com/docker-cloud/builds/advanced/
 # using ARG in FROM requires min v17.05.0-ce
-ARG  CACHE_TAG=latest
+ARG CACHE_TAG=latest
+ARG CCACHE_DIR
 
 FROM  qgis/qgis3-build-deps:${CACHE_TAG}
 MAINTAINER Denis Rouzaud <denis.rouzaud@gmail.com>
@@ -12,7 +13,11 @@ ENV CXX=/usr/lib/ccache/clang++
 ENV QT_SELECT=5
 ENV LANG=C.UTF-8
 
-COPY . /usr/src/QGIS
+COPY .. /usr/src/QGIS
+
+COPY $CACHE_DIR /root/.ccache
+ENV CCACHE_DIR=/root/.ccache
+RUN ccache -M 1G
 
 WORKDIR /usr/src/QGIS/build