diff --git a/roles/docker_s3_backup/files/scripts/determine-s3-keys-to-delete.py b/roles/docker_s3_backup/files/scripts/determine-s3-keys-to-delete.py
new file mode 100644
index 0000000..44435b0
--- /dev/null
+++ b/roles/docker_s3_backup/files/scripts/determine-s3-keys-to-delete.py
@@ -0,0 +1,21 @@
+#!/usr/bin/python
+import os
+
+
+def main():
+    s3_result = eval(os.getenv("S3_RESULTS"))
+    num_backups_to_keep = int(os.getenv("NUM_BACKUPS_TO_KEEP"))
+
+    items_to_delete = []
+    for res in s3_result:
+        s3_keys = res["s3_keys"]
+        # fetch all of the backups before the desired number.
+        # these are the ones we want to delete.
+        items_to_delete.extend(s3_keys[0:-num_backups_to_keep])
+
+    for item in items_to_delete:
+        print(item)
+
+
+if __name__ == "__main__":
+    main()