OAuth 2.0 authorization in PostgreSQL using Keycloak as an example

OAuth 2.0 Device Authorization Flow enables PostgreSQL to authenticate users through external identity providers like Keycloak, replacing traditional password-based authentication with centralized access control. The implementation involves configuring Keycloak realms and clients, setting up PostgreSQL configuration files (postgresql.conf, pg_hba.conf, pg_ident.conf), and writing a custom token validator in C that verifies JWT tokens by checking scopes and user identifiers. This approach is particularly useful for cloud environments and microservices architectures where centralized identity management and SSO are required.