If someone is interested, here is how we managed this:
- created a SSO user and added in DCAdmins group
- created a local vCenter account and modified defaut shell to bash
- writed python scripts that parse the vdcrepadmin (using the SSO user created below) and output the results in JSON files
- adds a root crontab (/etc/cron.d) to run theses scripts every 10 minutes
- on nagios side, writed a plugin that grab files from vCenter thanks to SFTP using local vCenter account and analyse the results.
With a simple wwwroot accessible outside of the vCenter it will be possible for python scripts to write files inside the directory thus make useless the local vCenter account and SFTP part.
But we did not find such directory.