added docker items for db

docs/docker/local-db-pg.md

@@ -0,0 +1,89 @@
+# Local Database With Scripts (PostgreSQL)
+
+When developing apps locally it can be really useful to have a dockerised database unique to the application.
+
+Often rather than just running a pre-built image, you'll want to run a database with some initial data, tables, or a schema.
+
+For this purpose we can create our own image that extends the base image and adds our own scripts.
+
+## Setup
+
+For most applications the directory structure will look something like this:
+
+```
+database/
+  Dockerfile
+  scripts/
+    01-create-tables.sql
+development/
+  compose.yml
+src/
+  ...
+tests/
+  ...
+```
+
+### Dockerfile
+
+Create a dockerfile in the `database/` directory:
+
+::: code-group
+
+```dockerfile [Dockerfile]
+FROM postgres:17
+
+# Setup the postgres environment variables
+ENV POSTGRES_USER=myuser
+ENV POSTGRES_PASSWORD=mypassword
+ENV POSTGRES_DB=mydatabase
+
+# Setup port
+EXPOSE 5432
+
+# Copy all the scripts into the container
+COPY ./scripts /docker-entrypoint-initdb.d/
+```
+
+:::
+
+::: danger
+
+As this is a local development database, we're using the a simple username and password. **Do not use this in production**.
+
+:::
+
+### Scripts
+
+Create any scripts you need in the `database/scripts/` directory. PostgreSQL will run these scripts in alphabetical order against the database specified in the `POSTGRES_DB` environment variable.
+
+::: code-group
+
+```sql [01-create-tables.sql]
+CREATE TABLE MyTable (
+    Id INT NOT NULL PRIMARY KEY,
+    Name VARCHAR(50) NOT NULL
+);
+```
+
+:::
+
+## Compose
+
+Lastly we need to create a `docker-compose.yml` file in the `development/` directory:
+
+::: code-group
+
+```yaml [compose.yml]
+services:
+  db:
+    build:
+      context: ../database
+      dockerfile: Dockerfile
+    volumes:
+      - db-data:/var/lib/postgresql/data
+    ports:
+      - "5432:5432"
+
+volumes:
+  db-data:
+```