diff --git a/service/gcbrun_experiment.py b/service/gcbrun_experiment.py
index f19ab493d..ea3f9c63d 100644
--- a/service/gcbrun_experiment.py
+++ b/service/gcbrun_experiment.py
@@ -20,6 +20,7 @@
 import logging
 import os
 import sys
+# Dummy
 
 # pytype: disable=import-error
 import github  # pylint: disable=import-error
diff --git a/service/pr_experiment_log.py b/service/pr_experiment_log.py
new file mode 100644
index 000000000..9bd1988e2
--- /dev/null
+++ b/service/pr_experiment_log.py
@@ -0,0 +1,4 @@
+"""Show PR experiment basic info."""
+import os
+
+print('PR: %s', os.getenv('PR_NUMBER'))
diff --git a/service/run_experiment_cloudbuild.yaml b/service/run_experiment_cloudbuild.yaml
index 1bb5b1b6f..b31af29e9 100644
--- a/service/run_experiment_cloudbuild.yaml
+++ b/service/run_experiment_cloudbuild.yaml
@@ -1,4 +1,10 @@
 steps:
+- name: 'gcr.io/cloud-builders/docker'
+  entrypoint: 'python3'
+  args:
+  - service/pr_experiment_log.py
+  env:
+  - 'PR_NUMBER=${_PR_NUMBER}'
 - name: 'gcr.io/cloud-builders/docker'
   args:
     - build