chore: slightly simpler quick start setup (#10933)

Co-authored-by: Melinda Fekete <melinda.fekete@getunleash.io>

docker-compose.postgres.yml

@@ -0,0 +1,21 @@
+services:
+  unleash-postgres:
+    build:
+      context: ./docker/local-postgres
+    container_name: unleash-postgres
+    environment:
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: password
+      POSTGRES_DB: postgres
+    ports:
+      - "5432:5432"
+    volumes:
+      - unleash-postgres-data:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      interval: 5s
+      timeout: 5s
+      retries: 12
+
+volumes:
+  unleash-postgres-data:

docker/local-postgres/Dockerfile

@@ -0,0 +1,3 @@
+FROM postgres:15
+
+COPY init-unleash.sql /docker-entrypoint-initdb.d/init-unleash.sql

docker/local-postgres/init-unleash.sql

@@ -0,0 +1,24 @@
+\set ON_ERROR_STOP on
+
+DO
+$$
+BEGIN
+   IF NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles WHERE rolname = 'unleash_user') THEN
+      CREATE ROLE unleash_user LOGIN PASSWORD 'password';
+   END IF;
+END
+$$;
+
+ALTER ROLE unleash_user CREATEDB;
+
+SELECT 'CREATE DATABASE unleash WITH OWNER unleash_user'
+ WHERE NOT EXISTS (SELECT 1 FROM pg_database WHERE datname = 'unleash');
+\gexec
+
+SELECT 'CREATE DATABASE unleash_test WITH OWNER unleash_user'
+ WHERE NOT EXISTS (SELECT 1 FROM pg_database WHERE datname = 'unleash_test');
+\gexec
+
+SELECT 'ALTER DATABASE unleash_test SET timezone TO ''UTC'''
+ WHERE EXISTS (SELECT 1 FROM pg_database WHERE datname = 'unleash_test');
+\gexec

website/docs/contributing/backend/overview.md

@@ -30,7 +30,19 @@ To run and develop Unleash, you need to have PostgreSQL 14.0+ locally.
 
 Unleash currently also works with PostgreSQL v14.0+, but this might change in a future feature release, and we have stopped running automatic integration tests below PostgreSQL 14. The current recommendation is to use a role with Owner privileges since Unleash uses Postgres functions to simplify our database usage.
 
-### Create a local unleash databases in postgres {#create-a-local-unleash-databases-in-postgres}
+### Create a local Unleash database in Postgres
+
+Start the ready-to-use Postgres container (first run builds a small image that
+executes the required SQL automatically):
+
+```bash
+$ docker compose -f docker-compose.postgres.yml up -d
+```
+
+The container exposes Postgres on `localhost:5432` with the expected role and
+databases already created. Stop it with `docker compose -f docker-compose.postgres.yml down`.
+
+If you prefer to run the SQL manually outside of Docker, you can execute:
 
 ```bash
 $ psql postgres <<SQL