Certman assumes the root certificates of the VPN CA are located in the same
directory as the binary, If that is not the case you need to copy over the
`ca.crt` and `ca.key` files before you are able to generate certificates
with this tool.
Additionally, the project is configured by the following environment
variables:
*`OAUTH2_CLIENT_ID` the Client ID, assigned during client registration
*`OAUTH2_CLIENT_SECRET` the Client secret, assigned during client registration
*`OAUTH2_AUTH_URL` the URL to the "/authorize" endpoint of the identity provider
*`OAUTH2_TOKEN_URL` the URL to the "/token" endpoint of the identity provider
*`OAUTH2_REDIRECT_URL` the redirect URL used by the app, usually the hostname suffixed by "/login/oauth2/redirect"
*`USER_ENDPOINT` the URL to the Identity provider user endpoint, for gitlab this is "/api/v4/user". The "username" attribute of the returned JSON will used for authentication.