How to correctly deploy Django + Postgres with Depot?

[hzwei]

I encountered the following error while deploying my Django web app with the latest remote builder:

2.946   File "/usr/local/lib/python3.10/site-packages/psycopg/_conninfo_attempts.py", line 50, in conninfo_attempts
2.946     raise e.OperationalError(str(last_exc))
2.946 django.db.utils.OperationalError: [Errno -5] No address associated with hostname

it seems like psycopg can no longer find the DATABASE_URL correctly. The problem is gone with fly deploy --depot=false, so i guess the problem is from Depot.

Any suggestions for how to fix it with the new builder?

[joshua-fly]

Can you post your dockerfile? Are you trying to access your database during your build? That’s not possible using Depot builders, for now.

[hzwei]

The DOCKERFILE is mostly the default one generated during fly launch:

ARG PYTHON_VERSION=3.10-slim-buster

FROM python:${PYTHON_VERSION}

ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

RUN mkdir -p /code

WORKDIR /code

COPY requirements.txt /tmp/requirements.txt
RUN set -ex && \
    pip install --upgrade pip && \
    pip install -r /tmp/requirements.txt && \
    rm -rf /root/.cache/
COPY . /code

ENV DJANGO_SETTINGS_MODULE "config.settings.production"
RUN python manage.py collectstatic --noinput
RUN python manage.py migrate

EXPOSE 8000

CMD ["gunicorn", "--bind", ":8000", "--workers", "2", "config.wsgi"]

except that I changed the config file to the production one, which read the .env, which contains the DATABASE_URL. Running python manage.py migrate requires the connection to the database.

So I guess all Django apps have to be deployed with the --depot=false flag?

[joshua-fly]

fly launch will have placed python manage.py migrate into your fly.toml as the release_command, which gets run in the production environment after the build. Your production environment likely has DATABASE_URL already set using fly secrets.

Running migrations in builds in not recommended. One reason: your production credentials in .env are embedded in the Docker image in the Fly Docker repository.

[hzwei]

thanks a lot!