diff --git a/.drone.yml b/.drone.yml
index 2cf8e56..17a02a3 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -35,6 +35,7 @@ steps:
   commands:
     - mkdir ~/.docker
     - "echo $HARBOR_DOCKER_AUTH > ~/.docker/config.json"
+    - echo "auth prefix: ${HARBOR_DOCKER_AUTH}"
     - >
       buildctl
       --addr tcp://buildkitd:1234