diff --git a/roles/install-yarn/README.rst b/roles/install-yarn/README.rst
index 0720e978a..18ffe3876 100644
--- a/roles/install-yarn/README.rst
+++ b/roles/install-yarn/README.rst
@@ -6,3 +6,8 @@ Install yarn from yarnpkg repos
    :default: {{ zuul.project.src_dir }}
 
    The directory to work in.
+
+.. zuul:rolevar:: yarn_lock_file_path
+   :default: {{ zuul_work_dir }}/yarn.lock
+
+   Path to yarn.lock file used by a project.
diff --git a/roles/install-yarn/defaults/main.yaml b/roles/install-yarn/defaults/main.yaml
index 9739eb171..e49463cca 100644
--- a/roles/install-yarn/defaults/main.yaml
+++ b/roles/install-yarn/defaults/main.yaml
@@ -1 +1,2 @@
 zuul_work_dir: "{{ zuul.project.src_dir }}"
+yarn_lock_file_path: "{{ zuul_work_dir }}/yarn.lock"
diff --git a/roles/install-yarn/tasks/main.yaml b/roles/install-yarn/tasks/main.yaml
index 21e8348c7..508aedef3 100644
--- a/roles/install-yarn/tasks/main.yaml
+++ b/roles/install-yarn/tasks/main.yaml
@@ -1,6 +1,6 @@
 - name: Check for yarn.lock file
   stat:
-    path: "{{ zuul_work_dir }}/yarn.lock"
+    path: "{{ yarn_lock_file_path }}"
     get_checksum: false
     get_mime: false
     get_md5: false