Understanding django.db.utils.OperationalError

strikeouts27 · October 4, 2023, 2:11am

I was following along in Django For Professionals and I got the following error message. I checked the documentation and it lists the error as an exception but does not provide much detail. I checked stackoverflow but I have not been able to find answers. Has anyone run into this error before?

I was following along in Django For Professionals and I got the following error message. I checked the documentation and it lists the error as an exception but does not provide much detail. I checked stackoverflow but I have not been able to find answers. Has anyone run into this error before?

Docker.yml file (updated) : Hastebin

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

Traceback (most recent call last):
django.db.utils.OperationalError: could not translate host name “db” to address: nodename nor servname provided, or not known

bluepuma77 · October 4, 2023, 5:58am

Hastebin is sh*t because it rate limits me when I try to look at it a second time. Why not just post your config here, use 3 backticks in front and after.

And I doubt this has anything to do with the Docker Hub product, which hosts container images.

strikeouts27 · October 4, 2023, 6:15am

@bluepuma77
TRACEBACK

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

Traceback (most recent call last):
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/manage.py", line 22, in <module>
    main()
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 446, in execute_from_command_line
    utility.execute()
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 440, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/management/base.py", line 414, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/management/base.py", line 460, in execute
    output = self.handle(*args, **options)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/management/base.py", line 98, in wrapped
    res = handle_func(*args, **kwargs)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/management/commands/migrate.py", line 91, in handle
    self.check(databases=[database])
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/management/base.py", line 487, in check
    all_issues = checks.run_checks(
                 ^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/checks/registry.py", line 88, in run_checks
    new_errors = check(app_configs=app_configs, databases=databases)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/core/checks/model_checks.py", line 36, in check_all_models
    errors.extend(model.check(**kwargs))
                  ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/models/base.py", line 1461, in check
    *cls._check_indexes(databases),
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/models/base.py", line 1864, in _check_indexes
    connection.features.supports_covering_indexes
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/utils/functional.py", line 49, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
                                         ^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/postgresql/features.py", line 84, in is_postgresql_11
    return self.connection.pg_version >= 110000
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/utils/functional.py", line 49, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
                                         ^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/postgresql/base.py", line 354, in pg_version
    with self.temporary_connection():
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/contextlib.py", line 137, in __enter__
    return next(self.gen)
           ^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/base/base.py", line 639, in temporary_connection
    with self.cursor() as cursor:
         ^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/utils/asyncio.py", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/base/base.py", line 284, in cursor
    return self._cursor()
           ^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/base/base.py", line 260, in _cursor
    self.ensure_connection()
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/utils/asyncio.py", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/base/base.py", line 243, in ensure_connection
    with self.wrap_database_errors:
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/utils.py", line 91, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/base/base.py", line 244, in ensure_connection
    self.connect()
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/utils/asyncio.py", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/base/base.py", line 225, in connect
    self.connection = self.get_new_connection(conn_params)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/utils/asyncio.py", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/django/db/backends/postgresql/base.py", line 203, in get_new_connection
    connection = Database.connect(**conn_params)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/andrewstribling/Desktop/Programming/projects/django/code/django_for_beginners_books/django_for_professionals/code/ch3-postgresql/.venv/lib/python3.11/site-packages/psycopg2/__init__.py", line 122, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
django.db.utils.OperationalError: could not translate host name "db" to address: nodename nor servname provided, or not known

docker-compose.yml

version: "3.9"

services:
  web:
    build: .
    command: python /code/manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    ports:
      - 8000:8000
    depends_on:
      - db

  db:
    image: postgres:13
    volumes:
      - postgres_data:/var/lib/postgresql/data/
    environment:
      - "POSTGRES_HOST_AUTH_METHOD=trust"

volumes:
  postgres_data:

Dockerfile

# Pull base image
FROM python:3.10.4-slim-bullseye

# Set environment variables
ENV PIP_DISABLE_PIP_VERSION_CHECK 1
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

# Set work directory
WORKDIR /code

# Install dependencies
COPY ./requirements.txt .
RUN pip install -r requirements.txt

# Copy project
COPY . .

strikeouts27 · October 4, 2023, 6:58am

After running docker build, somehow some way it started working. Its almost as if docker is utilizing psycopg instead of my enviornment.

I am not certain why it did not work correctly the first time but somehow some way it is has been resolved.

rimelek · October 4, 2023, 7:14am

Only the libraries in the docker image will be used

Guess: if you change the Dockerfile after first running docker compose up, the image will not be rebuilt unless you add the --build flag or build the image manually.

Indeed. I moved the topic to general discussion

Correction:

I wrote “docker libraries”. That was a mistake. I wanted to write “libraries in the docker image” so I fixed my post above.

strikeouts27 · January 2, 2024, 11:55am

It seems my error persists. I cannot seem to open my project with the run server command.

rimelek · January 2, 2024, 5:14pm

What happens when you try this example?

services:
  client:
    image: curlimages/curl:8.5.0
    entrypoint: "curl"
    command:
      - server
      - --retry
      - "3"
      - --retry-max-time
      - "3"
      - --retry-delay
      - "1"
      - --retry-connrefused
    depends_on:
      - server
  server:
    image: nginx:1.24.0

Run this command

docker compose run --rm client

You should get the nginx default page eventually. Probably immediately.

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Understanding django.db.utils.OperationalError

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