A sample set of configurations for running Django/Gunicorn apps in Docker. This config even supports zero-downtime deploys! Some implementation required.

docker-bootstrap.sh

#! /bin/bash
set -e;

MODE="api"

log() {
    echo "[$(date)] $@"
}

load_secrets() {
    if [ ! -f ./secrets.sh ]; then
        log "No secrets found!"
    else
        log "Sourcing secrets..."
        source ./secrets.sh;
    fi
}

update_codebase() {
    log "Updating codebase..."
    git pull
}

stop_scheduler() {
    log "Stopping scheduled tasks..."
    docker-compose stop beat
}

shutdown_queues() {
    log "Shutting down queues..."
    docker-compose run --rm api ./manage.py shutdown_queues
    log "Waiting for queues to become idle (15 sec)..."
    sleep 15;
}

do_migrate() {
    log "Migrating database..."
    docker-compose run --rm api ./manage.py migrate
}

deploy_worker() {
    docker-compose up -d --build worker
}

deploy_local_services() {
    log "Building new images..."
    docker-compose build beat monitor

    log "Deploying new containers..."
    docker-compose up -d beat monitor
}

deploy_www() {
    log "Building new images..."
    docker-compose build api

    log "Starting backup API version (zero-downtime)"
    docker-compose up -d api_backup
    sleep 5;

    log "Deploying new containers..."
    docker-compose up -d api
    sleep 5;
    do_migrate

    log "Removing old version (zero-downtime)..."
    docker-compose stop api_backup

    log "Rebuilding the backup API for later use (zero-downtime)..."
    docker-compose build api_backup
}

# Commands

do_up() {
    load_secrets
    if [ "$MODE" == "worker" ]; then
        deploy_worker
    elif [ "$MODE" == "api-only" ]; then
        deploy_www
    else
        deploy_www
        deploy_local_services
        deploy_worker
    fi
}

do_down() {
    load_secrets
    docker-compose down
}

do_upgrade() {
    load_secrets
    update_codebase
    if [ "$MODE" == "worker" ]; then
        shutdown_queues
        deploy_worker
    elif [ "$MODE" == "api-only" ]; then
        deploy_www
    else
        stop_scheduler
        shutdown_queues
        deploy_worker
        deploy_www
        deploy_local_services
    fi
}

# Begin Arg Parsing

if [ -n "$2" ]; then
    case $2 in
        -w|--worker)
            MODE="worker"
        ;;
        -a|--api)
            MODE="api"
        ;;
        --api-only)
            MODE="api-only"
        ;;
        *)
            log "Error: Unknown Mode: $2"
            exit -1;
        ;;
    esac
fi

case $1 in
    up)
        do_up
    ;;
    down)
       do_down
    ;;
    upgrade)
        do_upgrade
    ;;
    *)
        log "Error: Unknown Command"
        exit -1;
    ;;
esac

docker-compose.yml

version: "3"

services:

  api:
    build:
      context: ./api
    restart: always
    depends_on:
      - memcached
      - db
    environment:
      - RUN_MODE=api
      - MEMCACHED_URL=memcached:11211
      - ALLOWED_HOSTS
      - SECRET_KEY
      - DATABASE_URL
      - BROKER_URL
      - EMAIL_HOST
      - EMAIL_PORT
      - DEFAULT_FROM_EMAIL
      - EMAIL_HOST_USER
      - EMAIL_HOST_PASSWORD
      - STATIC_ROOT
    volumes:
      - /opt/volumes/staticfiles/:/opt/staticfiles
    ports:
      - 127.0.0.1:8000:8000

  api_backup:
    build:
      context: ./api
    restart: always
    depends_on:
      - memcached
      - db
    environment:
      - RUN_MODE=api
      - MEMCACHED_URL=memcached:11211
      - ALLOWED_HOSTS
      - SECRET_KEY
      - DATABASE_URL
      - BROKER_URL
      - EMAIL_HOST
      - EMAIL_PORT
      - DEFAULT_FROM_EMAIL
      - EMAIL_HOST_USER
      - EMAIL_HOST_PASSWORD
      - STATIC_ROOT
    volumes:
      - /opt/volumes/staticfiles/:/opt/staticfiles
    ports:
      - 127.0.0.1:8001:8000

  db:
    image: postgres:11
    restart: always
    expose:
      - "5432"
    environment:
      - POSTGRES_DB
      - POSTGRES_USER
      - POSTGRES_PASSWORD
    volumes:
      - /opt/volumes/data:/var/lib/postgresql/data

  # Auxiliary Services

  worker:
    build:
      context: ./api
    restart: always
    depends_on:
      - db
    environment:
      - RUN_MODE=worker
      - ALLOWED_HOSTS
      - SECRET_KEY
      - DATABASE_URL
      - BROKER_URL
      - EMAIL_HOST
      - EMAIL_PORT
      - DEFAULT_FROM_EMAIL
      - EMAIL_HOST_USER
      - EMAIL_HOST_PASSWORD
      - STATIC_ROOT

  beat:
    build:
      context: ./api
    restart: always
    depends_on:
      - db
    volumes:
      - /opt/volumes/scheduler/:/opt/scheduler
    environment:
      - RUN_MODE=beat
      - ALLOWED_HOSTS
      - SECRET_KEY
      - DATABASE_URL
      - BROKER_URL
      - EMAIL_HOST
      - EMAIL_PORT
      - DEFAULT_FROM_EMAIL
      - EMAIL_HOST_USER
      - EMAIL_HOST_PASSWORD
      - STATIC_ROOT
      
  memcached:
    image: bitnami/memcached:latest
    environment:
      - MEMCACHED_CACHE_SIZE=128

# Task Brokering

  broker:
    build:
      context: ./broker
    restart: always
    ports:
      - 127.0.0.1:15672:15672
    expose:
      - 5672
    environment:
      - BROKER_DEFAULT_USER
      - BROKER_DEFAULT_PASS
    volumes:
     - /opt/volumes/rabbitmq:/var/lib/rabbitmq

docker-entrypoint.sh

#! /bin/sh
# A basic entrypoint script
set -e;

log() {
    echo "[$(date)] $1";
}

start_api() {
    python manage.py collectstatic --no-input
    gunicorn <app name>.wsgi \
        -k gevent \
        -w 4 \
        --worker-connections=2000 \
        --backlog=1000 \
        -p gunicorn.pid \
        --bind=0.0.0.0:8000
}

start_monitor() {
    python manage.py monitor_cluster
}

start_beat() {
    celery -A <app name> beat -s /opt/scheduler/celerybeat-schedule
}

start_worker() {
    celery \
        -A <app name> worker \
        -l info \
        -Q <list all queues> \
        -E \
        --autoscale=20,3 \
        --max-tasks-per-child 100
}

# Begin Main

if [ -z "$RUN_MODE" ]; then
    log "No mode provided. Use: api, worker, beat, or monitor";
    exit 1;
fi

if [ "$RUN_MODE" = "worker" ]; then
    start_worker
elif [ "$RUN_MODE" = "monitor" ]; then
    start_monitor
elif [ "$RUN_MODE" = "beat" ]; then
    start_beat
elif [ "$RUN_MODE" = "api" ]; then
    start_api
else
    echo "Invalid RUN MODE $RUN_MODE";
fi