How Do I Locate an Upload Callback Failure?

How It Works

OBS upload callback allows the OBS server to automatically send an HTTP request to a specified callback URL after an object is successfully uploaded. The SDK supports upload callback for the following operations:

• PutObject or PutFile
• CompleteMultipartUpload

Troubleshooting Procedure

1. Check whether the callback fails based on the HTTP status code.

   Scenario	Returned Status Code	Description
   Both the upload and callback are successful.	200	Normal. CallbackBody can be read.
   The upload is successful but the callback fails.	203	The object has been stored, but the callback server returns a status code other than 200.
   The upload fails.	err != nil	The upload fails, and the callback is not triggered.

   If the status code is 203, the object has been successfully uploaded to OBS, but the callback fails. In this case, perform the following steps.

2. Check whether the callback URL is reachable. The most common cause of a callback failure is that the OBS server cannot access the callback URL. Ensure that:
   • The URL must be an HTTP/HTTPS address that is accessible over the public network.
   • The callback server must return the 200 status code. Otherwise, OBS considers the callback failed.

   Verification method: Use curl to simulate a callback request from an external network.

   curl -X POST http://your-server.com/callback \  
       -H "Content-Type: application/json" \   
       -d '{"bucket":"test","key":"obj","etag":"abc"}' \  
       -v

   If the curl operation fails, the callback service is unreachable. In this case, check the network configuration, firewall rules, and whether the service is running properly.

3. Check whether the callback URL is URL-encoded. If the URL contains special characters, such as CJK characters, spaces, ampersands (&), and equal signs (=), URL encoding must be performed first. Otherwise, the OBS server may fail to correctly parse the callback URL, resulting in a callback failure.
4. Check the logs of the callback server. If the callback URL is reachable but the callback still fails, check the logs of the callback server. Common issues include:
   • Data not correctly processed: An error is reported when the server parses the callback request body. For example, the server does not recognize the format after template variables such as $(bucket) are replaced.
   • No response body returned: The server successfully processes the request but does not return a response body, or returns a status code other than 200.
   • Network timeout: The server takes too long to process the request, causing the callback on OBS to time out.