add startup command example

Author: Philipp Kübler

README.md

@@ -69,6 +69,37 @@ Make sure to adjust your `.env` accordingly and set `APP_URL` to `http://localho
 
 Run `docker-compose up` to start the services.
 
+### Startup Commands
+
+Further commands can be defined via ENV variable `STARTUP_COMMANDXXX`, which are executed at container start before the actual command.
+
+The commands must be numbered sequentially and start with 1 (e.g. `STARTUP_COMMAND1=command`, `STARTUP_COMMAND2=...`).
+
+```yml
+version: '3.7'
+services:
+  app:
+    image: sourceboat/docker-laravel
+    command: /home/app/run-prod.sh
+    restart: unless-stopped
+    environment:
+      - PHP_OPCACHE_VALIDATE_TIMESTAMPS=1
+      - PHP_MEMORY_LIMIT=1G
+      - STARTUP_COMMAND1=php artisan migrate --force
+      - STARTUP_COMMAND2=php artisan horizon:restart
+    volumes:
+      - ./:/opt/app:cached
+    ports:
+      - "8080:8080"
+    depends_on:
+      - mysql
+  mysql:
+    image: mysql:8.0
+    environment:
+      - "MYSQL_ROOT_PASSWORD=secret"
+      - "MYSQL_DATABASE=default"
+```
+
 ### Production
 
 `WIP`
@@ -80,6 +111,7 @@ Check [releases](https://github.com/sourceboat/docker-laravel/releases) for all
 ## Credits
 
 - [Phil-Bastian Berndt](https://github.com/pehbehbeh)
+- [Philipp Kübler](https://github.com/PKuebler)
 - [All Contributors](https://github.com/sourceboat/docker-laravel/graphs/contributors)
 
 ## License