Docker PostgreSQL error

Traceback (most recent call last):
  File "main.py", line 67, in <module>
    update_channel_loop()
  File "main.py", line 46, in update_channel_loop
    data_list = parse_all()
  File "/usr/src/app/news_parser.py", line 57, in parse_all
    db_data = read_db()
  File "/usr/src/app/db_engine.py", line 19, in read_db
    conn = psycopg2.connect(dbname=DB_NAME, user=DB_USERNAME, password=DB_PASS, host=DB_HOST)
  File "/usr/local/lib/python3.8/site-packages/psycopg2/__init__.py", line 127, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError: could not connect to server: Connection refused
        Is the server running on host "localhost" (::1) and accepting
        TCP/IP connections on port 5432?
could not connect to server: Connection refused
        Is the server running on host "localhost" (127.0.0.1) and accepting
        TCP/IP connections on port 5432?