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.

README.md

@@ -188,6 +188,76 @@ exit 0
 
 Please do not forget to make the script executable (chmod +x certbot-renew.sh).
 
+Configuration
+=============
+
+Most of the configuraiton is supposed to be handled through environment
+variables in the `docker-compose.yaml`.
+
+### Mailman-web
+These are the settings that you MUST change before deploying:
+
+- `SERVE_FROM_DOMAIN`: The domain name from which Django will be served. To be
+  added to `ALLOWED_HOSTS` in django settings. Default value is not set.
+
+- `HYPERKITT_API_KEY`: Hyperkitty's API Key, should be set to the same value as
+  set for the mailman-core.
+
+These are the settings that are set to sane default and you do not need to
+change them unless you know what you want.
+
+- `DATABASE_URL`: URL of the type
+  `driver://user:password@hostname:port/databasename` for the django to use. If
+  not set, the default is set to
+  `sqlite:///opt/mailman-web-data/mailmanweb.db`. The standard
+  docker-compose.yaml comes with it set to a postgres database. It is not must
+  to change this if you are happy with postgresql.
+
+- `MAILMAN_REST_URL`: The URL to the Mailman core's REST API server.  Defaut
+  value is `http://mailman-core:8001`.
+
+- `MAILMAN_REST_USER`: Mailman's REST API username. Default value is `restadmin`
+
+- `MAILMAN_REST_PASSWORD`: Mailman's REST API user's password. Default value is
+  `restpass`
+
+- `DJANGO_HOST_IP`: IP of the container from which the django will be
+  served. Default value is `172.19.199.3`.
+
+- `SMTP_HOST`: IP Address/hostname from which you will be sending
+  emails. Default value is `172.19.199.1`, which is the address of the Host OS.
+
+- `SMTP_PORT`: Port used for SMTP. Default is `25`.
+
+
+### Mailman-Core
+
+These are the variables that you MUST change before deploying:
+
+- `HYPERKITT_API_KEY`: Hyperkitty's API Key, should be set to the same value as
+  set for the mailman-core.
+
+- `DATABASE_CLASS`: Default value is `mailman.database.sqlite.SQLiteDatabase`.
+
+These are the variables that you don't need to change if you are using a
+standard version of docker-compose.yaml from this repository.
+
+- `MM_HOSTNAME`: Default value is `mailman-core`
+
+- `SMTP_HOST`: IP Address/hostname from which you will be sending
+  emails. Default value is `172.19.199.1`, which is the address of the Host OS.
+
+- `SMTP_PORT`: Port used for SMTP. Default is `25`.
+
+- `HYPERKITTY_API_URL`: Default value is `http://mailman-web:8000/hyperkitty`
+
+- `DATABASE_URL`: URL of the type
+  `driver://user:password@hostname:port/databasename` for the django to use. If
+  not set, the default is set to
+  `sqlite:///opt/mailman-web-data/mailmanweb.db`. The standard
+  docker-compose.yaml comes with it set to a postgres database. It is not must
+  to change this if you are happy with postgresql.
+
 
 LICENSE
 =======