request help: Could I use X-ID-Token header to visit the route protected by apisix openid-connect plugin

[haowang-pony]

Issue description

I want to implement such workflow

However I met two problems:

1. The openid-connect plugin only read access_token when verify the jwt token.

   apisix/apisix/plugins/openid-connect.lua

   Line 161 in fa8a34f

   local has_token, token, err = get_bearer_access_token(ctx)

2. the openid-connect plugin only support introspection_endpoint, could we add cert endpoint in config which used to get public key from keycloak and such that we could verify the token after receive public key from keycloak. Because I don't want define public_key in ApisixRoute. It's ugly and it would have problem if keycloak public key was changed.
   why I don't use authz-keycloak plugin: authz-keycloak must need jwt token when request apisix, but I want also want to implement the following workflow, therefore I give up to use authz-keycloak plugin

For first problems, maybe we could just add get_bearer_id_token() in introspect function when there is no access token. If it makes sense, I could help to do that.

For second problems, I'm not sure whether it's allowed to add cert endpoint in openid-connect config. If it's not allowed, I hope authz-keycloak could support this workflow. It should be copy the main logic of openid-connect plugin. If this make sense, I could also contribute about this and write an article about how to integrate with keycloak.

Environment

• apisix version (cmd: apisix version):
• OS (cmd: uname -a):
• OpenResty / Nginx version (cmd: nginx -V or openresty -V):
• etcd version, if have (cmd: run curl http://127.0.0.1:9090/v1/server_info to get the info from server-info API):
• apisix-dashboard version, if have:
• the plugin runner version, if the issue is about a plugin runner (cmd: depended on the kind of runner):
• luarocks version, if the issue is about installation (cmd: luarocks --version):

[spacewander]

PR is welcome!
For the second problem, we can try to add cert endpoint for it.

[spacewander]

BTW, please submit a separate PR for each problem.