Cannot connect to PosgreSQL using unix domain socket

I can connect to PostgreSQL database using asyncpg with specifying DSN string as follows:

conn = await asyncpg.connect(
    'postgres:///sampledb?host=/cloudsql/xxx:asia-northeast1:yyy/.s.PGSQL.5432&user=postgres&password=pass')

(This PostgreSQL database is GCP Cloud SQL)

UsingTortoise.init(), however, I cannot connect to the database with the same DSN string.

await Tortoise.init(
    config={
        'connections': {
            'default': 'postgres:///sampledb?host=/cloudsql/xxx:asia-northeast1:yyy/.s.PGSQL.5432&user=postgres&password=pass'
        },
        'apps': {
            'models': {
                'models': ['__main__'],
                'default_connection': 'default',
            }
        }})

The code above raises OSError: Multiple exceptions: [Errno 61] Connect call failed ('::1', 5432, 0, 0), [Errno 61] Connect call failed ('127.0.0.1', 5432)

I also tried the following connection settings, but TypeError: __init__() missing 1 required positional argument: 'port' occurred.

await Tortoise.init(
    config={
        'connections': {
            'default': {
                "engine": "tortoise.backends.asyncpg",
                "credentials": {
                    "database": 'sampledb',
                    "host": '/cloudsql/xxx:asia-northeast1:yyy/.s.PGSQL.5432',
                    "password": "pass",
                    "user": "postgres",
                }
            }
        'apps': {
            'models': {
                'models': ['__main__'],
                'default_connection': 'default',
            }
        }})

How can I connect to the database using unix socket?

Start at Tortoise.init connection handling and the tortoise.backends.asyncpg credentials path; compare them with the working asyncpg DSN example. Done means a PostgreSQL Unix-domain socket connection works through the supported configuration without the reported connection or missing-port errors.