FServer list: Return the username if the user has been granted access to the server

scripts-available/CDB_FederatedServer.sql

@@ -192,6 +192,34 @@ END
 $$
 LANGUAGE PLPGSQL IMMUTABLE PARALLEL SAFE;
 
+-- Given an server name, returns the username used in the configuration if the caller has rights to access it
+CREATE OR REPLACE FUNCTION @extschema@.__CDB_FS_get_usermapping_username(internal_server_name NAME)
+RETURNS text
+AS $$
+DECLARE
+    role_name name := @extschema@.__CDB_FS_Generate_Server_Role_Name(internal_server_name);
+    username text;
+BEGIN
+    BEGIN
+        EXECUTE 'SET LOCAL ROLE ' || quote_ident(role_name);
+    EXCEPTION WHEN OTHERS THEN
+        RETURN NULL;
+    END;
+
+    SELECT (SELECT option_value FROM pg_options_to_table(u.umoptions) WHERE option_name LIKE 'user') as name INTO username
+        FROM pg_foreign_server s
+        LEFT JOIN pg_user_mappings u
+        ON u.srvid = s.oid
+        WHERE s.srvname = internal_server_name
+        ORDER BY 1;
+
+    RESET ROLE;
+
+    RETURN username;
+END
+$$
+LANGUAGE PLPGSQL VOLATILE PARALLEL UNSAFE;
+
 
 --------------------------------------------------------------------------------
 -- Public functions
@@ -345,8 +373,7 @@ BEGIN
         (SELECT option_value FROM pg_options_to_table(s.srvoptions) WHERE option_name LIKE 'dbname') AS "DBName",
         CASE WHEN (SELECT NOT option_value::boolean FROM pg_options_to_table(s.srvoptions) WHERE option_name LIKE 'updatable') THEN 'read-only' ELSE 'read-write' END AS "ReadMode",
 
-        -- Read username from pg_user_mappings
-        (SELECT option_value FROM pg_options_to_table(u.umoptions) WHERE option_name LIKE 'user') AS "Username"
+        @extschema@.__CDB_FS_get_usermapping_username(s.srvname)::text AS "Username"
     FROM pg_foreign_server s
     LEFT JOIN pg_user_mappings u
     ON u.srvid = s.oid

test/CDB_FederatedServer.sql

@@ -175,6 +175,9 @@ SELECT '9.3', cartodb.CDB_Federated_Server_Register_PG(server => 'myRemote4'::te
 
 \echo '## Granting access to a user works'
 SELECT '9.5', cartodb.CDB_Federated_Server_Grant_Access(server => 'myRemote3', db_role => 'cdb_fs_tester'::name);
+\c contrib_regression cdb_fs_tester
+SELECT '9.55', cartodb.CDB_Federated_Server_List_Servers();
+\c contrib_regression postgres
 SELECT '9.6', cartodb.CDB_Federated_Server_Grant_Access(server => 'does not exist', db_role => 'cdb_fs_tester'::name);
 SELECT '9.7', cartodb.CDB_Federated_Server_Grant_Access(server => 'myRemote3', db_role => 'does not exist'::name);
 

test/CDB_FederatedServer_expect

@@ -47,6 +47,9 @@ ERROR:  Could not create server myRemote4: permission denied for foreign-data wr
 You are now connected to database "contrib_regression" as user "postgres".
 ## Granting access to a user works
 9.5|
+You are now connected to database "contrib_regression" as user "cdb_fs_tester".
+9.55|(myRemote3,postgres_fdw,localhost,5432,,read-only,fdw_user)
+You are now connected to database "contrib_regression" as user "postgres".
 ERROR:  Server "does not exist" does not exist
 ERROR:  Could not grant access on "myRemote3" to "does not exist": role "does not exist" does not exist
 ## Granting access again raises a notice