Apache Airflow can't connect to localhost database-CodePudding

I am using Airflow and Postgres on Docker. I have the following connection where I do a DML command (outside Airflow):

 # Constructor method initializing the connection to DB and creating cursor
    def __init__(self, db="projeto-pos", user="postgres", host="localhost", password=my_psswd, port="5433"):
        self.conn = psycopg2.connect(
            database=db, host=host, port=port, password=password, user=user)
        self.cur = self.conn.cursor()

I am using Docker and the Postgres' container is available on localhost:5433. I can perfectly use Pgadmin and do DML commands from Python.

I instantiated the Postgress (db ojbect) class and created the following task in a DAG:

insert_into = PythonOperator(
        task_id='insert_into',
        python_callable=db.insert_into
    )

However, when I open the Airflow UI this messages pops up and I can't run the DAG:

Broken DAG: [/opt/airflow/dags/projeto_api.py] Traceback (most recent call last):
  File "/opt/airflow/dags/functions/db_manipulation.py", line 10, in __init__
    database=db, host=host, port=port, password=password, user=user)
  File "/home/airflow/.local/lib/python3.7/site-packages/psycopg2/__init__.py", line 122, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError: connection to server at "localhost" (127.0.0.1), port 5433 failed: Connection refused
    Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (::1), port 5433 failed: Cannot assign requested address
    Is the server running on that host and accepting TCP/IP connections?

I am using this Dockerfile for Airflow. I also tried in the "connections" section in the Airflow UI, but I got the same message. I know for sure that the connection is up and running.

CodePudding user response：

The hostname of postgres is "postgres" not "localhost".

this name is defined by the name of the postgres service in the docker-compose.

services:
  postgres:
    image: postgres:13

also, you can see the connection string in the docker-compose (in bold)

AIRFLOW__DATABASE__SQL_ALCHEMY_CONN: postgresql psycopg2://airflow:airflow@postgres/airflow