inet_server_addr() is a system function which returns the IP address which the current client is connected to.
inet_server_addr() was added in PostgreSQL 8.0.
inet_server_addr() is called without any arguments, and returns the server IP address as the
inet data type, or
NULL if the current connection is via a Unix-domain socket.
In PostgreSQL 13 and earlier,
inet_server_addr() will always return
NULL if executed by a parallel worker. This has been fixed for PostgreSQL 14 (commit 5a6f9bce), but has not been backpatched to earlier versions.
Example output when connected via TCP/IP:
postgres=# SELECT inet_server_addr(); inet_server_addr ------------------ 10.11.9.1 (1 row)
Example output when connected via a Unix-domain socket:
postgres=# SELECT inet_client_addr(); inet_server_addr ------------------ (1 row)