added database setup script

scripts/create_db_user.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+set -e # Exit immediately if a command exits with a non-zero status.
+
+# --- 1. Set up Connection Variables ---
+HOST=$POSTGRES_HOST
+PORT=$POSTGRES_PORT
+DB_NAME=$NEW_DB_NAME
+DB_USER=$NEW_DB_USER
+DB_PASSWORD=$NEW_DB_PASSWORD
+
+# --- 2. Build the SQL Commands ---
+# NOTE: The IF NOT EXISTS ensures the script can be run safely multiple times.
+SQL_COMMANDS=$(cat <<-END_SQL
+    -- Create user role with login and password
+    DO
+    \$body\$
+    BEGIN
+        IF NOT EXISTS (
+            SELECT
+            FROM   pg_catalog.pg_user
+            WHERE  usename = '$DB_USER') THEN
+            CREATE ROLE $DB_USER WITH LOGIN PASSWORD '$DB_PASSWORD';
+        END IF;
+    END
+    \$body\$;
+
+    -- Create database owned by the new user (if it doesn't exist)
+    SELECT 'CREATE DATABASE $DB_NAME OWNER $DB_USER'
+    WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = '$DB_NAME')\gexec
+END_SQL
+)
+
+# --- 3. Execute the SQL Commands ---
+echo "Attempting to connect to $HOST to execute SQL..."
+echo "$SQL_COMMANDS" | psql \
+    --host=$HOST \
+    --port=$PORT \
+    --username=$POSTGRES_ADMIN_USER \
+    --dbname=postgres \
+    --set ON_ERROR_STOP=on
+
+echo "PostgreSQL database '$DB_NAME' and user '$DB_USER' created/verified successfully."