diff --git a/.github/scripts/action.yaml b/.github/scripts/action.yaml
index f67f2a5229..b7904cb16d 100644
--- a/.github/scripts/action.yaml
+++ b/.github/scripts/action.yaml
@@ -33,6 +33,9 @@ inputs:
   showcase_mode:
     description: true if we need to download the showcase api definitions
     required: false
+  api_def_dir:
+    description: Path to api definitions (e.g. googleapis). Used when a custom set of protos is needed.
+    required: false
   token:
     description: Personal Access Token
     required: true
@@ -76,10 +79,12 @@ runs:
         --target_branch "${BASE_REF}" \
         --current_branch "${HEAD_REF}" \
         --showcase_mode "${SHOWCASE_MODE}" \
+        --api_def_dir "${API_DEF_DIR}" \
         --image_tag "${IMAGE_TAG}"
     env:
       BASE_REF: ${{ inputs.base_ref }}
       HEAD_REF: ${{ inputs.head_ref }}
       IMAGE_TAG: ${{ inputs.image_tag }}
       SHOWCASE_MODE: ${{ inputs.showcase_mode }}
+      API_DEF_DIR: ${{ inputs.api_def_dir }}
       GH_TOKEN: ${{ inputs.token }}
diff --git a/.github/scripts/hermetic_library_generation.sh b/.github/scripts/hermetic_library_generation.sh
index 5da0e64c3a..3d9c04be95 100755
--- a/.github/scripts/hermetic_library_generation.sh
+++ b/.github/scripts/hermetic_library_generation.sh
@@ -50,6 +50,10 @@ case "${key}" in
     showcase_mode="$2"
     shift
     ;;
+  --api_def_dir)
+    api_def_dir="$2"
+    shift
+    ;;
   *)
     echo "Invalid option: [$1]"
     exit 1
@@ -92,12 +96,16 @@ git checkout "${current_branch}"
 git show "${target_branch}":"${generation_config}" > "${baseline_generation_config}"
 
 # download api definitions from googleapis repository
-googleapis_commitish=$(grep googleapis_commitish "${generation_config}" | cut -d ":" -f 2 | xargs)
-api_def_dir=$(mktemp -d)
-git clone https://github.com/googleapis/googleapis.git "${api_def_dir}"
-pushd "${api_def_dir}"
-git checkout "${googleapis_commitish}"
-popd
+if [[ -z "${api_def_dir}" ]];then
+  googleapis_commitish=$(grep googleapis_commitish "${generation_config}" | cut -d ":" -f 2 | xargs)
+  api_def_dir=$(mktemp -d)
+  git clone https://github.com/googleapis/googleapis.git "${api_def_dir}"
+  pushd "${api_def_dir}"
+  git checkout "${googleapis_commitish}"
+  popd
+else
+  ls "${api_def_dir}/google/cloud/vertexai/v1"
+fi
 
 # we also setup showcase
 if [[ "${showcase_mode}" == "true" ]]; then