Question 82579 in Docker Question posted in
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Alembic migration with FastAPI + Docker: Connection to port 5432 in localhost fails when I try to run migrations

Currently I am trying to learn about Api development with FastAPI and I am trying to dockerize my project. However, when I try to run the database migrations with alembic in Docker by using docker run sm-api_api alembic upgrade head I get the following error:

File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 3280, in _wrap_pool_connect
    return fn()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 310, in connect
    return _ConnectionFairy._checkout(self)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 868, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 476, in checkout
    rec = pool._do_get()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/impl.py", line 256, in _do_get
    return self._create_connection()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 256, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 371, in __init__
    self.__connect()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 665, in __connect
    with util.safe_reraise():
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    compat.raise_(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/util/compat.py", line 208, in raise_
    raise exception
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 661, in __connect
    self.dbapi_connection = connection = pool._invoke_creator(self)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/create.py", line 590, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/default.py", line 597, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/usr/local/lib/python3.10/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 5432 failed: Connection refused
        Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (::1), port 5432 failed: Cannot assign requested address
        Is the server running on that host and accepting TCP/IP connections?


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/bin/alembic", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.10/site-packages/alembic/config.py", line 590, in main
    CommandLine(prog=prog).main(argv=argv)
  File "/usr/local/lib/python3.10/site-packages/alembic/config.py", line 584, in main
    self.run_cmd(cfg, options)
  File "/usr/local/lib/python3.10/site-packages/alembic/config.py", line 561, in run_cmd
    fn(
  File "/usr/local/lib/python3.10/site-packages/alembic/command.py", line 322, in upgrade
    script.run_env()
  File "/usr/local/lib/python3.10/site-packages/alembic/script/base.py", line 569, in run_env
    util.load_python_file(self.dir, "env.py")
  File "/usr/local/lib/python3.10/site-packages/alembic/util/pyfiles.py", line 94, in load_python_file
    module = load_module_py(module_id, path)
  File "/usr/local/lib/python3.10/site-packages/alembic/util/pyfiles.py", line 110, in load_module_py
    spec.loader.exec_module(module)  # type: ignore
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/usr/src/app/alembic/env.py", line 81, in <module>
    run_migrations_online()
  File "/usr/src/app/alembic/env.py", line 69, in run_migrations_online
    with connectable.connect() as connection:
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 3234, in connect
    return self._connection_cls(self, close_with_result=close_with_result)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 96, in __init__
    else engine.raw_connection()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 3313, in raw_connection
    return self._wrap_pool_connect(self.pool.connect, _connection)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 3283, in _wrap_pool_connect
    Connection._handle_dbapi_exception_noconnection(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 2117, in _handle_dbapi_exception_noconnection
    util.raise_(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/util/compat.py", line 208, in raise_
    raise exception
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 3280, in _wrap_pool_connect
    return fn()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 310, in connect
    return _ConnectionFairy._checkout(self)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 868, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 476, in checkout
    rec = pool._do_get()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/impl.py", line 256, in _do_get
    return self._create_connection()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 256, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 371, in __init__
    self.__connect()
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 665, in __connect
    with util.safe_reraise():
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    compat.raise_(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/util/compat.py", line 208, in raise_
    raise exception
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/pool/base.py", line 661, in __connect
    self.dbapi_connection = connection = pool._invoke_creator(self)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/create.py", line 590, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/default.py", line 597, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/usr/local/lib/python3.10/site-packages/psycopg2/__init__.py", line 122, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) connection to server at "localhost" (127.0.0.1), port 5432 failed: Connection refused
        Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (::1), port 5432 failed: Cannot assign requested address
        Is the server running on that host and accepting TCP/IP connections?

(Background on this error at: https://sqlalche.me/e/14/e3q8)

My docker compose file is like this:

version: '3'
services:
  api:
    build: .
    depends_on:
      - postgres
    ports:
      - 8000:8000
    environment:
      - DATABASE_HOSTNAME=${DATABASE_HOST}
      - DATABASE_PORT=${DATABASE_PORT}
      - DATABASE_PASSWORD=${DATABASE_PASSWORD}
      - DATABASE_NAME=${DATABASE_NAME}
      - DATABASE_USERNAME=${DATABASE_USERNAME}
      - SECRET_KEY=${SECRET_KEY}
      - ALGORITHM=${ALGORITHM}
      - ACCESS_TOKEN_EXPIRE_MINUTES=${ACCESS_TOKEN_EXPIRE_TIME}

  postgres:
    image: postgres
    environment:
      - POSTGRES_PASSWORD=${DATABASE_PASSWORD}
      - POSTGRES_DB=${DATABASE_NAME}
    ports:
      - 5432:5432
    volumes:
      - postgres-db:/var/lib/postgresql/data

volumes:
  postgres-db:

I already tried to kill the port and run it again, but it did not solve my problem. Does anyone know what the problem is?

Edit:
My Docker file:

FROM python:3.10.5

WORKDIR /usr/src/app

COPY requirements.txt ./

RUN pip install --no-cache-dir -r requirements.txt

COPY . .

CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

And my .env file:

DATABASE_HOST=localhost
DATABASE_PORT=5432
DATABASE_PASSWORD={password}
DATABASE_NAME=SM_API
DATABASE_USERNAME=postgres
SECRET_KEY={secret key}
ALGORITHM=HS256
ACCESS_TOKEN_EXPIRE_TIME = 30
Tags:

2

Answers


  1. 0

    Taking a look at the following snippet

    conn = _connect(dsn, connection_factory=connection_factory, **kwasync) psycopg2.OperationalError: connection to server at "localhost" (127.0.0.1), port 5432 failed: Connection refused
    Is the server running on that host and accepting TCP/IP connections?

    Maybe as the DATABASE_HOSTNAME you pass 127.0.0.1 ?

    From the container’s point of view its loopback interface doesn’t accept any connections at 5432, your host machine does tho.

    You should refer to the postgres container instead. Since the services in docker compose are discoverable you could use service name.

    You should edit your .env file to

    DATABASE_HOST=postgres
...
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  2. 0

    You are connecting to localhost (or 127.0.0.1) which is, from the container point of view, itself. You probably want to change that line in your docker compose as DATABASE_HOSTNAME=postgres, so it refers to the postgres container.

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