Use locals where possible

hack/libhack/challenge.sh

@@ -14,13 +14,13 @@ source "${libhack_dir}/common.sh"
 
 challenge::build() {
     pushd "${CHALLENGE_PATH}"
-    ARGS="--build-arg NOFRONTEND=1" build_challenge_internal
+    args="--build-arg NOFRONTEND=1" build_challenge_internal
     popd
 }
 
 challenge::build_with_frontend() {
     pushd "${CHALLENGE_PATH}"
-    ARGS="--no-cache" build_challenge_internal
+    args="--no-cache" build_challenge_internal
     popd
 }
 
@@ -28,11 +28,14 @@ build_challenge_internal() {
     docker build -t "${IMAGE_NAME}"                           \
                  -f "${BUILD_CONTEXT}/Dockerfile"             \
                  --build-arg BUILD_CONTEXT="${BUILD_CONTEXT}" \
-                 ${ARGS} .
+                 ${args} .
 }
 
 challenge::run() {
     pushd "${TFW_PATH}"
+    local mount_baseimage
+    local mount_challenge
+    local mount_volumes
     if [ "${HOTRELOAD:-0}" == "1" ]; then
         [ -d "${BASEIMAGE_PATH}" ] && mount_baseimage="-v ${BASEIMAGE_PATH}/lib/tfw:/usr/local/lib/tfw"
         mount_challenge="-v ${CHALLENGE_PATH}/solvable/src:/srv/.tfw"