Add support for proper database migrations (fix pwreset table) (compd…

…emocracy#542)

* Removed empty script file.

* Reorganized files for easier database migrations. Documented manual migrations.

* Improved inline comment for db init.

* Added disclaimer about backups.

docs/deployment.md

@@ -107,6 +107,41 @@ We use Google to automatically translate submitted comments into the language of
    [base64-encoder]: https://codepen.io/bsngr/pen/awuDh
 
 
+## Database Migrations
+
+When we need to update the Polis database, we use SQL migration files.
+
+During initial provisioning of your Docker containers, all the migrations will
+be applied in order, and you won't need to think about this.
+
+But if we update the database schema after your initial provisioning of your
+server via Docker, you'll need to manually apply each new SQL migration.
+
+- Please note: **Backups are your responsibility.** These instructions assume
+  the data is disposable, and do not attempt to make backups.
+    - Pull requests are welcome if you'd like to see more guidance on this.
+- Your database data is stored on a docker volume, which means that it will
+  persist even when you destroy all your docker containers. Be mindful of this.
+    - You can remove ALL volumes defined within a `docker-compose` file via: `docker-compose down --volumes`
+    - You can remove ONE volume via `docker volume ls` and `docker volume rm <name>`
+- SQL migrations can be found in [`server/postgres/migrations/`][] of this
+  repo.
+- The path to the SQL file will be relative to its location in the docker
+  container filesystem, not your host system.
+
+For example, if we add the migration file
+`server/postgres/migrations/000001_update_pwreset_table.sql`, you'd run on your
+host system:
+
+```
+docker-compose exec postgres psql --username postgres --dbname polis-dev --file=/docker-entrypoint-initdb.d/000001_update_pwreset_table.sql
+```
+
+You'd do this for each new file.
+
+   [`server/postgres/migrations/`]: /server/postgres/migrations
+
+
 ## Contribution notes
 
 Please help us out as you go in setting things up by improving the deployment code and documentation!

server/Dockerfile-db

@@ -1,3 +1,6 @@
 FROM postgres:12.4-alpine
 
-COPY ./postgres/db_setup_draft.sql /docker-entrypoint-initdb.d/
+# Used when no existing database on postgres volume, including first initialization.
+# See: docs/deployment.md#database-migrations
+# See: https://github.com/docker-library/docs/blob/master/postgres/README.md#initialization-scripts
+COPY ./postgres/migrations/*.sql /docker-entrypoint-initdb.d/

server/postgres/migrations/000001_update_pwreset_table.sql

@@ -0,0 +1,2 @@
+ALTER TABLE password_reset_tokens RENAME COLUMN pwresettoken TO token;
+ALTER TABLE password_reset_tokens RENAME TO pwreset_tokens;