feat: add support for copying over additional data migrations

add docs for new env var and for how to load new data for different
environments.

Author: angela-tran

bin/init.sh

@@ -8,6 +8,14 @@ rm -f django.db
 
 # run database migrations
 
+if [[ ${DJANGO_LOAD_SAMPLE_DATA:-true} = false ]]; then
+    if [[ -d ${DJANGO_MIGRATIONS_DIR} ]]; then
+        cp ${DJANGO_MIGRATIONS_DIR}/0002_*.py ./benefits/core/migrations/
+    else
+        echo "Warning: DJANGO_MIGRATION_DIR needs to be a directory... not loading any data"
+    fi
+fi
+
 python manage.py migrate
 
 # create a superuser account for backend admin access

docs/configuration/data.md

@@ -68,6 +68,35 @@ Run these commands from within the repository root, inside the devcontainer:
 bin/init.sh
 ```
 
+## Loading new data for different environment
+
+Django will run all migration files found in an app's `migrations` module.
+
+To load new data for a different environment:
+
+1. (Optional) Set an environment variable `DJANGO_LOAD_SAMPLE_DATA` to `false` if you don't want the `core` app's sample data to be loaded.
+1. Create a data migration file, and make sure the name is prefixed with `0002`. (The migration process for Benefits expects data migration files to named as such). The basic structure for the contents of this file is:
+```python
+from django.db import migrations
+
+
+def load_data(app, *args, **kwargs):
+    pass
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("core", "0001_initial"),
+    ]
+
+    operations = [
+        migrations.RunPython(load_data),
+    ]
+```
+1. Put this file in the core app's `migrations` module
+1. If `DJANGO_LOAD_SAMPLE_DATA` is `false`, you can also set [`DJANGO_MIGRATIONS_DIR`](../environment-variables/#django_migrations_dir) to a directory path, and put your data migration there.
+
+
 [core-models]: https://github.com/cal-itp/benefits/blob/dev/benefits/core/models.py
 [django-load-initial-data]: https://docs.djangoproject.com/en/4.0/howto/initial-data/
 [eligibility-server]: https://docs.calitp.org/eligibility-server

docs/configuration/environment-variables.md

@@ -113,6 +113,15 @@ The log level used in the application's logging configuration.
 
 By default the application sends logs to `stdout`.
 
+
+### `DJANGO_MIGRATIONS_DIR`
+
+!!! warning "Deployment configuration"
+
+    You may change this setting when deploying the app to a non-localhost domain
+
+If [`DJANGO_LOAD_SAMPLE_DATA`](#django_load_sample_data) is `false`, then you can set `DJANGO_MIGRATIONS_DIR` to the path of a directory containing data migrations that you want to be run. Those data migration files need to be prefixed with `0002` so that the [helper migration file](data.md)) can find it. See [Configuration data](./data.md) for more on loading data for different environments.
+
 ### `DJANGO_SECRET_KEY`
 
 !!! warning "Deployment configuration"