Unable to connect from Docker container running django to SQL Server using the FreeTDS driver

Software versions

Django: 5.0.6
mssql-django: 1.5
python: 3.12.3
SQL Server: 2019
OS: ubuntu:24.04

Table schema and Model No schema yet, as it is a fresh project.

Database Connection Settings

DATABASES = {
    "default": {
        "ENGINE": "mssql",
        "NAME": "ZollApp",
        "USER": "zoll",
        "PASSWORD": "123passwordZoll",
        "HOST": "zoll_app_mssql",  # Container Name
        "OPTIONS": {
            "driver": "FreeTDS",
            "unicode_results": True,
            "host_is_server": True,
            "driver_supports_utf8": True,
        },
    }
}

Problem description and steps to reproduce When attempting to apply migrations to create the initial schemas, I encounter an error stating: "Adaptive Server is unavailable or does not exist." Although I am able to ping the SQL Server from my "web" container where Django is running, I am unable to establish a connection with the mssql-django library. Interestingly, I can successfully access the database using a SQL client with the same credentials. In the past I used SqlAlchemy with pymsql with the same docker setup and it worked flawlessly.

Error message/stack trace

django.db.utils.OperationalError: ('08S01', '[08S01] [FreeTDS][SQL Server]Unable to connect: Adaptive Server is unavailable or does not exist (20009) (SQLDriverConnect)')

Any other details that can be helpful

FROM --platform=linux/amd64/v2 ubuntu:24.04

WORKDIR /opt/

# Set environment variables
ENV PYTHONFAULTHANDLER=1 \
  PYTHONUNBUFFERED=1 \
  PYTHONHASHSEED=random \
  PIP_NO_CACHE_DIR=off \
  PIP_DISABLE_PIP_VERSION_CHECK=on \
  PIP_DEFAULT_TIMEOUT=100 \
  # Poetry's configuration:
  POETRY_NO_INTERACTION=1 \
  POETRY_VIRTUALENVS_CREATE=false \
  POETRY_VIRTUALENVS_IN_PROJECT=false \
  POETRY_CACHE_DIR='/var/cache/pypoetry' \
  POETRY_VERSION=1.7.1

RUN apt-get update && apt-get install -y curl build-essential apt-transport-https gpg
# adding custom MS repository
RUN curl -fsSL https://packages.microsoft.com/keys/microsoft.asc | gpg --dearmor -o /usr/share/keyrings/microsoft-prod.gpg
RUN curl -fsSL https://packages.microsoft.com/config/ubuntu/24.04/prod.list | tee /etc/apt/sources.list.d/mssql-release.list

# install SQL Server drivers
RUN apt-get update 
RUN ACCEPT_EULA=Y apt-get install -y python3.12 python3.12-dev python3-pip python3.12-venv unixodbc-dev unixodbc freetds-dev freetds-bin tdsodbc libpango-1.0-0 libpangoft2-1.0-0
RUN apt-get install -y iputils-ping

# Install Poetry and Dependencies
RUN pip3 install --break-system-packages --upgrade pip setuptools
ARG POETRY_VERSION=1.8.2
ENV POETRY_HOME=/opt/poetry\
  PATH="${PATH}:/opt/poetry/bin"
RUN python3 -m venv ${POETRY_HOME} &&\
  ${POETRY_HOME}/bin/pip install poetry==${POETRY_VERSION} &&\
  poetry config virtualenvs.create false

# Copy only the dependencies files to the container
COPY poetry.lock pyproject.toml /opt/
# Install project dependencies
RUN poetry install --no-root --no-interaction --no-ansi --no-dev

# Copy the rest of the application code to the container
COPY . /opt/

# Expose the port Gunicorn will listen on
EXPOSE 8000

RUN python3 /opt/zoll_app/manage.py migrate --noinput

# Run gunicorn
CMD ["python3", "/opt/zoll_app/manage.py", "runserver", "0.0.0.0:8000"]

services:
  sqlserver:
    image: mcr.microsoft.com/mssql/server:2019-latest
    container_name: zoll_app_mssql
    restart: always
    environment:
      MSSQL_SA_PASSWORD: "Zoll#1337"
      ACCEPT_EULA: "Y"
      MSSQL_PID: Developer
    ports:
      - 1433:1433
    volumes:
      - ./.docker/mssql-data:/var/opt/mssql

  redis:
    image: redis:latest
    container_name: zoll_app_redis
    restart: always
    command: ["redis-server", "--appendonly", "no"]
    ports:
      - 6379:6379
    volumes:
      - ./.docker/redis/data:/data

  flower:
    image: mher/flower:0.9.7
    container_name: zoll_app_flower
    command: ["flower", "--broker=redis://redis:6379", "--port=5555"]
    ports:
      - 5555:5555
    depends_on:
      - redis

  web:
    build:
      context: .
      dockerfile: Dockerfile
    platform: linux/amd64/v2
    container_name: zoll_app_web
    restart: always
    volumes:
      - .:/zoll_app
    ports:
      - "8000:8000"
    depends_on:
      - sqlserver
      - redis

Thanks for your help 🤗

microsoft / mssql-django

Unable to connect from Docker container running django to SQL Server using the FreeTDS driver #393