Hi, Gilles.
Let's handle one issue at a time. So far, your IDP becoming unavailable is the most serious one:
>And why idp server became unavailable with error 503 ?
Have you already modified any its configuration files? Or your only change so far have been creating new TR with metadata you produced? Could you please try next steps first?
1. Log in to container
2. Restart web UI service: `# service identity restart`
3. Restart IDP service: `# service idp restart`
4. Check whether your IDP is accessible now. Try to access url like `https://YOUR.HOST.NAME/idp/shibboleth` (use your Gluu Server's hostname). If you see a page with metadata, don't follow the rest of the steps
5. If you don't see it, stop IDP: `# service idp stop`
6. Remove, or move to other place IDP's log files: `rm -f /opt/shibboleth-idp/logs/*; rm -f /opt/gluu/jetty/idp/logs/*`
7. Start the service and wait for 5 minutes: `# service idp start`
8. Gather all newly-created logs from both those directories, package them and share for us to review.
Also, you could consider reinstalling it from scratch, if you think some modifications you did could cause it. It may actually take less time than fixing it.