Strange issue with Open OnDemand + mod_auth_mellon

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1

Hi All,

I’m seeing a strange issue with Open OnDemand + mod_auth_mellon on Ubuntu 24.04.

The exact same Entra ID / Mellon configuration works on another OOD deployment running in a Rocky Linux. However, on Ubuntu:

  • /mellon/metadata works
  • /pun/sys/dashboard redirects correctly to /mellon/login
  • Entra authentication succeeds
  • Browser POSTs to /mellon/postResponse
  • /mellon/postResponse returns HTTP 400 Bad Request

Browser dev tools show:

  • Request Method: POST
  • SAMLResponse and RelayState are present

Ubuntu:

  • Apache 2.4.58
  • libapache2-mod-auth-mellon 0.19.0

Rocky (working):

  • mod_auth_mellon 0.14.0

Has anyone seen /mellon/postResponse return 400 on Ubuntu while the same IdP configuration works on Rocky?

Interesting Observation

If I access OOD via the “My Apps” application tile after authentication, the application works correctly.

However, direct access to:

https://<dns>.com/pun/sys/dashboard/

eventually results in the HTTP 400 response from /mellon/postResponse.

Any pointers would be appreciated.

Thanks!

2

I’d suggest increasing the logging level of mod_auth_mellon. That’s at least a start to figure out what it doesn’t like about the IdP’s response.