[docker] multiarch support: linux/amd64,linux/arm64,linux/arm/v7

make docker.buildx : build and push multiarch build.
(it can't be only build)

use buildx with the --cache-from and --cache-to options to cache the layers
(only the last built is cached)

manage

@@ -152,6 +152,10 @@ docker.push() {
     docker.build push
 }
 
+docker.buildx() {
+    docker.build buildx
+}
+
 # shellcheck disable=SC2119
 docker.build() {
     pyenv.install
@@ -210,23 +214,34 @@ docker.build() {
         GITHUB_USER=$(echo "${GIT_URL}" | sed 's/.*github\.com\/\([^\/]*\).*/\1/')
         SEARX_IMAGE_NAME="${SEARX_IMAGE_NAME:-${GITHUB_USER:-searxng}/searxng}"
 
+        BUILD="build"
+        if [ "$1" = "buildx" ]; then
+            # buildx includes the push option
+            CACHE_TAG="${SEARX_IMAGE_NAME}:latest-build-cache"
+            BUILD="buildx build --platform linux/amd64,linux/arm64,linux/arm/v7 --push --cache-from=type=registry,ref=$CACHE_TAG --cache-to=type=registry,ref=$CACHE_TAG,mode=max"
+            shift
+        fi
+        build_msg DOCKER "Build command: ${BUILD}"
+
         # build Docker image
         build_msg DOCKER "Building image ${SEARX_IMAGE_NAME}:${SEARX_GIT_VERSION}"
-        sudo docker build \
+        # shellcheck disable=SC2086
+        docker $BUILD \
+         --build-arg BASE_IMAGE="${DEPENDENCIES_IMAGE_NAME}" \
          --build-arg GIT_URL="${GIT_URL}" \
          --build-arg SEARX_GIT_VERSION="${SEARX_GIT_VERSION}" \
          --build-arg VERSION_GITCOMMIT="${VERSION_GITCOMMIT}" \
          --build-arg LABEL_DATE="$(date -u +"%Y-%m-%dT%H:%M:%SZ")" \
          --build-arg LABEL_VCS_REF="$(git rev-parse HEAD)" \
          --build-arg LABEL_VCS_URL="${GIT_URL}" \
-	 --build-arg TIMESTAMP_SETTINGS="$(git log -1 --format="%cd" --date=unix -- searx/settings.yml)" \
-	 --build-arg TIMESTAMP_UWSGI="$(git log -1 --format="%cd" --date=unix -- dockerfiles/uwsgi.ini)" \
+         --build-arg TIMESTAMP_SETTINGS="$(git log -1 --format="%cd" --date=unix -- searx/settings.yml)" \
+         --build-arg TIMESTAMP_UWSGI="$(git log -1 --format="%cd" --date=unix -- dockerfiles/uwsgi.ini)" \
          -t "${SEARX_IMAGE_NAME}:latest" -t "${SEARX_IMAGE_NAME}:${SEARX_GIT_VERSION}" .
 
         if [ "$1" = "push" ]; then
-	    sudo docker push "${SEARX_IMAGE_NAME}:latest"
-	    sudo docker push "${SEARX_IMAGE_NAME}:${SEARX_GIT_VERSION}"
-        fi
+	        docker push "${SEARX_IMAGE_NAME}:latest"
+	        docker push "${SEARX_IMAGE_NAME}:${SEARX_GIT_VERSION}"
+	    fi
     )
     dump_return $?
 }