Dockerized Django App on DigitalOcean Times Out Uploading to S3-Compatible Storage

I'm running a Dockerized Django app on a DigitalOcean Droplet that syncs static assets to an S3-compatible storage (DigitalOcean Spaces). However, the S3 upload times out when executed from within the Docker container, even though it works fine on my local setup and when run directly on the Droplet.

A simple test case in s3upload.py (with foobar.txt in the same directory) demonstrates the issue:

PYTHONCopied
from boto3.s3.transfer import S3Transfer
import boto3
import logging

logging.getLogger().setLevel(logging.DEBUG)

client = boto3.client('s3', 
                      aws_access_key_id="…", 
                      aws_secret_access_key="…", 
                      region_name="ams3", 
                      endpoint_url="https://ams3.digitaloceanspaces.com")
transfer = S3Transfer(client)
bucket_name = "…"
transfer.upload_file("foobar.txt", bucket_name, "foobar.txt")

When running this script inside the Docker container, I get the following error:

TRACEBACKCopied
Traceback (most recent call last):
  File "/usr/local/lib/python3.13/site-packages/boto3/s3/transfer.py", line 372, in upload_file
    future.result()
    ~~~~~~~~~~~~~^^
  File "/usr/local/lib/python3.13/site-packages/s3transfer/futures.py", line 103, in result
    return self._coordinator.result()
           ~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/local/lib/python3.13/site-packages/s3transfer/futures.py", line 264, in result
    raise self._exception
  File "/usr/local/lib/python3.13/site-packages/s3transfer/tasks.py", line 135, in __call__
    return self._execute_main(kwargs)
  File "/usr/local/lib/python3.13/site-packages/s3transfer/tasks.py", line 158, in _execute_main
    return_value = self._main(**kwargs)
  File "/usr/local/lib/python3.13/site-packages/s3transfer/upload.py", line 796, in _main
    client.put_object(Bucket=bucket, Key=key, Body=body, **extra_args)
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/botocore/client.py", line 569, in _api_call
    return self._make_api_call(operation_name, kwargs)
           ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^
    raise error_class(parsed_response, operation_name)
botocore.exceptions.ClientError: An error occurred (RequestTimeout) when calling the PutObject operation (reached max retries: 4): None

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/app/s3upload.py", line 14, in <module>
    transfer.upload_file("foobar.txt", bucket_name, "foobar.txt")
    ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/boto3/s3/transfer.py", line 378, in upload_file
    raise S3UploadFailedError(
    ...<3 lines>...
    )
boto3.exceptions.S3UploadFailedError: Failed to upload foobar.txt to [bucketname]/foobar.txt: An error occurred (RequestTimeout) when calling the PutObject operation (reached max retries: 4): None

Testing reveals this behavior:

• On my local test environment:

  • python s3upload.py works
  • docker compose exec -T django-web python s3upload.py works

• On the DigitalOcean Droplet:

  • python s3upload.py works
  • docker compose exec -T django-web python s3upload.py times out

I've verified that host-level network settings (like firewalls) and credentials are correct, so this appears to be specific to the Docker setup on the Droplet.

Below are the relevant Docker configuration files:

Docker Compose (compose.yml):

YAMLCopied
services:

  db:
    image: postgres:17
    environment:
      POSTGRES_DB: ${POSTGRES_DB}
      POSTGRES_USER: ${POSTGRES_USER}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
    ports:
      - "5432:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data
    env_file:
      - .env

  django-web:
    build: .
    container_name: django-docker
    ports:
      - "80:80"
    expose:
      - "80"
    depends_on:
      - db
    environment:
      SECRET_KEY: ${SECRET_KEY}
      DEBUG: ${DEBUG}

      POSTGRES_DB: ${POSTGRES_DB}
      POSTGRES_USER: ${POSTGRES_USER}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}

      DATABASE_HOST: ${DATABASE_HOST}
      DATABASE_PORT: ${DATABASE_PORT}
    env_file:
      - .env

volumes:
  postgres_data:

Dockerfile:

DOCKERFILECopied
# Stage 1: Build

# Use the official Python runtime image
FROM python:3.13-slim AS builder 

# Create the app directory
RUN mkdir /app

# Set the working directory inside the container
WORKDIR /app

# Set environment variables 
# Prevents Python from writing pyc files to disk
ENV PYTHONDONTWRITEBYTECODE=1
#Prevents Python from buffering stdout and stderr
ENV PYTHONUNBUFFERED=1 

# Upgrade pip
RUN pip install --upgrade pip 

# Copy the Django project  and install dependencies
COPY requirements.txt  /app/

# run this command to install all dependencies 
RUN pip install --no-cache-dir -r requirements.txt


# Stage 2: Run production code

FROM python:3.13-slim

RUN useradd -m -r appuser && mkdir /app && chown -R appuser /app

# Copy the Python dependencies from the builder stage
COPY --from=builder /usr/local/lib/python3.13/site-packages/ /usr/local/lib/python3.13/site-packages/
COPY --from=builder /usr/local/bin/ /usr/local/bin/

# Set the working directory
WORKDIR /app

# Copy application code
COPY --chown=appuser:appuser . .

# Set environment variables to optimize Python
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1 

# Switch to non-root user
USER appuser

# Expose the Django port
EXPOSE 80

# # Migrate the DB
# RUN ["python", "manage.py", "migrate"]

# Gather static assets

# ---> This is the s3 command not working
# RUN ["python", "manage.py", "collectstatic", "--no-input"]

# Run the app via the gunicorn server
CMD ["gunicorn", "--bind", "0.0.0.0:80", "--workers", "3", "fonts.wsgi"]
# python manage.py migrate && python manage.py collectstatic --no-input && gunicorn myapp.wsgi

I’m seeking advice on further debugging steps or potential causes for the S3 request timeouts within Docker on the Droplet. Any guidance appreciated.