Mount bazel cache folder of HOME as tmpfs with exec option

This saves at least 6GB of diskspace and shrinks the
container_shadow_workspace by 90%

CMK-21123

Change-Id: If105e100a786343a281cc61e9bd7d7d0b2ba473a

buildscripts/scripts/utils/docker_image_aliases_helper.groovy

@@ -90,6 +90,7 @@ inside_container = {Map arg1=[:], Closure arg2 ->
             + (args.ulimit_nofile ? ["--ulimit nofile=${args.ulimit_nofile}:${args.ulimit_nofile}"] : [])
             + (privileged ? ["-v /var/run/docker.sock:/var/run/docker.sock"] : [])
             + ["-v \"${container_shadow_workspace}/home:${env.HOME}\""]
+            + "--tmpfs ${env.HOME}/.cache/bazel:exec,size=10g,mode=777"
             + (mount_credentials ? ["-v ${env.HOME}/.cmk-credentials:${env.HOME}/.cmk-credentials"] : [])
             + (mount_host_user_files ? ["-v /etc/passwd:/etc/passwd:ro -v /etc/group:/etc/group:ro"] : [])
             + ((mount_reference_repo && reference_repo_dir) ? ["-v ${reference_repo_dir}:${reference_repo_dir}:ro"] : [])
@@ -117,6 +118,8 @@ inside_container = {Map arg1=[:], Closure arg2 ->
 
             # create mount dirs for $HOME/.cache (not to confuse with <checkout_dir>/.cache)
             mkdir -p "${container_shadow_workspace}/home_cache"
+            mkdir -p "${container_shadow_workspace}/home_cache/bazel"
+
             mkdir -p "${container_shadow_workspace}/home/.cache"
 
             # create mount dirs for <checkout_dir>/.cache

scripts/run-in-docker.sh

@@ -69,6 +69,7 @@ mkdir -p "${CONTAINER_SHADOW_WORKSPACE}/home"
 touch "${CONTAINER_SHADOW_WORKSPACE}/home/.cmk-credentials"
 mkdir -p "${CONTAINER_SHADOW_WORKSPACE}/home/.cache"
 mkdir -p "${CONTAINER_SHADOW_WORKSPACE}/home_cache"
+mkdir -p "${CONTAINER_SHADOW_WORKSPACE}/home_cache/bazel"
 mkdir -p "${CONTAINER_SHADOW_WORKSPACE}/omd_build"
 mkdir -p "${CHECKOUT_ROOT}/shared_cargo_folder"
 mkdir -p "${CHECKOUT_ROOT}/omd/build"
@@ -83,6 +84,14 @@ mkdir -p "${HOME}/shared_cargo_folder"
 # UNCONDITIONAL MOUNTS
 DOCKER_MOUNT_ARGS="-v ${CONTAINER_SHADOW_WORKSPACE}/home:${HOME}"
 DOCKER_MOUNT_ARGS="${DOCKER_MOUNT_ARGS} -v ${CONTAINER_SHADOW_WORKSPACE}/home_cache:${HOME}/.cache"
+
+# with "--mount" the execution of binaries is not allowed and can not be changed
+# use "--tmpfs" instead
+# see https://docs.docker.com/engine/storage/tmpfs/#options-for---tmpfs
+# mount the bazel cache as tmpfs to save minimum 6GB of diskspace
+DOCKER_MOUNT_ARGS="${DOCKER_MOUNT_ARGS} --tmpfs ${HOME}/.cache/bazel:exec,size=10g,mode=777"
+# other folders in HOME/.cache are not touched to ensure a fast venv creation
+
 DOCKER_MOUNT_ARGS="${DOCKER_MOUNT_ARGS} -v ${HOME}/shared_cargo_folder:${CHECKOUT_ROOT}/shared_cargo_folder"
 DOCKER_MOUNT_ARGS="${DOCKER_MOUNT_ARGS} -v ${CHECKOUT_ROOT}:${CHECKOUT_ROOT}"
 DOCKER_MOUNT_ARGS="${DOCKER_MOUNT_ARGS} -v ${GIT_COMMON_DIR}:${GIT_COMMON_DIR}"