I have a secured architecture with Keycloak (see Securing thorntail service with KEYCLOAK for schema). It works well. But now, I can't figure out how to make service A getting some info from secured Service B, alone.
If the flow is FrontEnd (authenticated, so has a token) / service A / secured Service B then Ok, A access B. But, for example first time in the morning (@startup) service A needs to get some infos from service B, no token to forward ... how to do it ?
Client Credentials Flow is what you need. https://www.keycloak.org/docs/latest/authorization_services/#_service_protection_permission_api_papi
curl -X POST \
-H "Content-Type: application/x-www-form-urlencoded" \
-d 'grant_type=client_credentials&client_id=${client_id}&client_secret=${client_secret}' \
"http://localhost:8080/auth/realms/${realm_name}/protocol/openid-connect/token"
This is from keycloak documentation (https://www.keycloak.org/docs/latest/authorization_services/#_service_protection_permission_api_papi).
Check also this: https://auth0.com/docs/flows/concepts/client-credentials