Can't use custom hostname for Django app with runserver_plus

Question

I'm running a Django application from a Docker container using docker compose. My goal is to run the application from a custom hostname, which I'll call myapp.com. Here are the steps I've taken thus far:

• Added 127.0.0.1 myapp.com to my /etc/hosts file
• Added a local CA using mkcert -install
• Created cert and key files using mkcert -cert-file cert.pem -key-file key.pem myapp.com 127.0.0.1
• Added 'django_extensions' to the INSTALLED_APPS list in settings.py
• Added 'myapp.com' to the ALLOWED_HOSTS list in settings.py
• Set the startup command in docker-compose.yaml to python manage.py runserver_plus --cert-file cert.pem --key-file key.pem myapp.com:8000

When I start up the project with docker compose up, the server boots up successfully and the console claims that it's running with no issues at https://myapp.com:8000. However, attempting to actually access my application by visiting that URL does not work, giving an error page that says this:

This site can't be reached
myapp.com unexpectedly closed the connection.

Attempting to curl that URL from my machine's command line also fails with this message, no matter what flags I use:

curl: (35) schannel: failed to receive handshake, SSL/TLS connection failed

However, running the curl command from within the docker container gives a different message (below), and running the command with the --insecure flag makes it work fine and return the main page of the app.

curl: (60) SSL certificate problem: unable to get local issuer certificate

Any ideas on how to debug this and/or solve this issue? The curl error messages mentioning SSL suggest that something might be wrong with the cert files, but I'm not sure what I would need to do to fix that.

The full contents of my settings.py and docker-compose.yaml files can be found below.

"""
Django settings for cas_testing_project project.

Generated by 'django-admin startproject' using Django 3.2.16.

For more information on this file, see
https://docs.djangoproject.com/en/3.2/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/3.2/ref/settings/
"""

from pathlib import Path

# Build paths inside the project like this: BASE_DIR / 'subdir'.
BASE_DIR = Path(__file__).resolve().parent.parent


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/3.2/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = 'CENSORED'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = [
    'localhost',
    'myapp.com',
    '.ngrok-free.app',
]


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'livereload',
    'uniauth',
    'django_extensions',
    'cas_testing',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

AUTHENTICATION_BACKENDS = [
    'django.contrib.auth.backends.ModelBackend',
    'uniauth.backends.CASBackend',
]

ROOT_URLCONF = 'cas_testing_project.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'cas_testing_project.wsgi.application'


# Database
# https://docs.djangoproject.com/en/3.2/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}


# Password validation
# https://docs.djangoproject.com/en/3.2/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/3.2/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/3.2/howto/static-files/

STATIC_URL = '/static/'

# Default primary key field type
# https://docs.djangoproject.com/en/3.2/ref/settings/#default-auto-field

DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'

LOGIN_URL = "/accounts/login/"
UNIAUTH_LOGIN_DISPLAY_STANDARD = False
UNIAUTH_LOGOUT_CAS_COMPLETELY = True

version: "3.9"
 
services:
  mssql_db:
    build:
      context: .
      dockerfile: mssql.Dockerfile
    volumes:
      - ./mssqldata:/var/opt/mssql/data
    ports:
      - "1433:1433"
    environment:
      - MSSQL_SA_PASSWORD=${SA_PASSWORD}
    env_file:
      - ./.env
  db:
    image: mysql
    volumes:
      - ./mysqldata/db:/var/lib/mysql
    restart: unless-stopped
    environment:
      - MYSQL_DATABASE=${RDS_GSB_DB}
      - MYSQL_USER=${RDS_GSB_USER}
      - MYSQL_PASSWORD=${RDS_GSB_PASS}
      - MYSQL_ROOT_PASSWORD=${RDS_GSB_PASS}
  web:
    build: .
    command: python manage.py runserver_plus --cert-file cert.pem --key-file key.pem myapp.com:8000
    volumes:
      - .:/code
    ports:
      - "8000:8000"
    env_file:
      - ./.env
    environment:
      - FIRST_RUN=${FIRST_RUN}
    depends_on:
      - db
      - mssql_db