Change all the configuration variables to ENVIRONMENT VARS.

Following 12factor principle for app development, all the configuration
variables for the docker images can now be setup using environment vars.

The default values are set using the run.sh script in both mailman-web
and mailman-core containers.

Mailman-core is now run by "run.sh" which traps SIGTERM and performs
mailman stop for graceful exit of mailman core.

web/mailman-web/settings.py

@@ -27,6 +27,7 @@ https://docs.djangoproject.com/en/1.8/ref/settings/
 
 # Build paths inside the project like this: os.path.join(BASE_DIR, ...)
 import os
+import dj_database_url
 
 BASE_DIR = os.path.dirname(os.path.abspath(__file__))
 
@@ -47,16 +48,17 @@ SITE_ID = 1
 ALLOWED_HOSTS = [
     "localhost",  # Archiving API from Mailman, keep it.
     # "lists.your-domain.org",
+    os.environ.get('SERVE_FROM_DOMAIN'),
     # Add here all production URLs you may have.
     "mailman-web",
 ]
 
 # Mailman API credentials
-MAILMAN_REST_API_URL = 'http://mailman-core:8001'
-MAILMAN_REST_API_USER = 'restadmin'
-MAILMAN_REST_API_PASS = 'restpass'
-MAILMAN_ARCHIVER_KEY = 'ASmallAPIKey'
-MAILMAN_ARCHIVER_FROM = ('mailman-web', '172.19.199.3')
+MAILMAN_REST_API_URL = os.environ.get('MAILMAN_REST_URL', 'http://mailman-core:8001')
+MAILMAN_REST_API_USER = os.environ.get('MAILMAN_REST_USER', 'restadmin')
+MAILMAN_REST_API_PASS = os.environ.get('MAILMAN_REST_PASSWORD', 'restpass')
+MAILMAN_ARCHIVER_KEY = os.environ.get('HYPERKITTY_API_KEY')
+MAILMAN_ARCHIVER_FROM = ('mailman-web', os.environ.get('DJANGO_HOST_IP', '172.19.199.3'))
 
 # Application definition
 
@@ -142,8 +144,12 @@ WSGI_APPLICATION = 'wsgi.application'
 # https://docs.djangoproject.com/en/1.8/ref/settings/#databases
 
 
-DATABASES['default'] = dj-database-url.config(conn_max_age=600)
-
+# This uses $DATABASE_URL from the environment variable to create a
+# django-style-config-dict.
+# https://github.com/kennethreitz/dj-database-url
+DATABASES = {
+    'default': dj_database_url.config(conn_max_age=600)
+}
 
 # If you're behind a proxy, use the X-Forwarded-Host header
 # See https://docs.djangoproject.com/en/1.8/ref/settings/#use-x-forwarded-host
@@ -262,13 +268,11 @@ SERVER_EMAIL = 'root@localhost.local'
 
 # Change this when you have a real email backend
 EMAIL_BACKEND = 'django.core.mail.backends.smtp.EmailBackend'
-EMAIL_HOST = '172.19.199.1'
-EMAIL_PORT = 25
+EMAIL_HOST = os.environ.get('SMTP_HOST', '172.19.199.1')
+EMAIL_PORT = os.environ.get('SMTP_PORT', 25)
 EMAIL_HOST_USER = ''
 EMAIL_HOST_PASSWORD = ''
 EMAIL_USE_TLS = False
-DEFAULT_FROM_EMAIL = 'Admin <admin@localhost.local>'
-
 
 # Compatibility with Bootstrap 3
 from django.contrib.messages import constants as messages  # flake8: noqa
@@ -404,6 +408,8 @@ LOGGING = {
             'class': 'logging.StreamHandler',
             'formatter': 'simple',
         },
+        # TODO: use an environment variable $DJ_LOG_URL to configure the logging
+        # using an environment variable.
     },
     'loggers': {
         'django.request': {