1. You should consider using [mod_auth_openidc](https://github.com/zmartzone/mod_auth_openidc) which Gluu supports. Or if you prefer nginx, use [lua-resty-openidc](https://github.com/zmartzone/lua-resty-openidc). In this case php would pick up the user info from the environment variables.
2. You could take a look at [phpOIDC](https://bitbucket.org/PEOFIAMP/phpoidc) from NRI, which has been certified. If you have any luck with phpOIDC, please write a blog and post a link to this issue.