db: Add support for key-value pair DSNs in postgresql

tests/test_db.py

@@ -281,3 +281,20 @@ def test_optimistic_locking(node_factory, bitcoind):
         l1.rpc.newaddr()
 
     assert(l1.daemon.is_in_log(r'Optimistic lock on the database failed'))
+
+
+@unittest.skipIf(os.environ.get('TEST_DB_PROVIDER', None) != 'postgres', "Only applicable to postgres")
+def test_psql_key_value_dsn(node_factory, db_provider, monkeypatch):
+    from pyln.testing.db import PostgresDb
+
+    # Override get_dsn method to use the key-value style DSN
+    def get_dsn(self):
+        print("hello")
+        return "postgres://host=127.0.0.1 port={port} user=postgres password=password dbname={dbname}".format(
+            port=self.port, dbname=self.dbname
+        )
+
+    monkeypatch.setattr(PostgresDb, "get_dsn", get_dsn)
+    l1 = node_factory.get_node()
+    opt = [o for o in l1.daemon.cmd_line if '--wallet' in o][0]
+    assert('host=127.0.0.1' in opt)

wallet/db_postgres.c

@@ -17,7 +17,24 @@
 
 static bool db_postgres_setup(struct db *db)
 {
-	db->conn = PQconnectdb(db->filename);
+	size_t prefix_len = strlen("postgres://");
+
+	/* We attempt to parse the connection string without the `postgres://`
+	prefix first, so we can correctly handle the key-value-pair style of
+	DSN that postgresql supports. If that fails we try with the full
+	string, which matches the `scheme://user:password@host:port/dbname`
+	style of DSNs. The call to `PQconninfoParse` here is just to verify
+	`PQconnectdb` would be able to parse it correctly, that's why the
+	result is discarded again immediately. */
+	PQconninfoOption *info =
+	    PQconninfoParse(db->filename + prefix_len, NULL);
+
+	if (info != NULL) {
+		PQconninfoFree(info);
+		db->conn = PQconnectdb(db->filename + prefix_len);
+	} else {
+		db->conn = PQconnectdb(db->filename);
+	}
 
 	if (PQstatus(db->conn) != CONNECTION_OK) {
 		db->error = tal_fmt(db, "Could not connect to %s: %s", db->filename, PQerrorMessage(db->conn));