Add script to wait for a service

docker-compose.yml

@@ -5,43 +5,48 @@ services:
     ports:
       - "8000:8000"
     environment:
-      DATABASE_HOST: 'db'
+      DATABASE_HOST: 'database'
       CELERY_BROKER: 'redis://redis:6379/0'
       CELERY_BACKEND: 'redis://redis:6379/1'
     depends_on:
-      - db
+      - database
     command: >
-      sh -c "sleep 5 &&
+      sh -c "./scripts/wait_for_service database 3306 &&
              python manage.py migrate &&
              python manage.py runserver 0.0.0.0:8000"
+
   celery-worker:
     build: .
     environment:
-      DATABASE_HOST: 'db'
+      DATABASE_HOST: 'database'
       CELERY_BROKER: 'redis://redis:6379/0'
       CELERY_BACKEND: 'redis://redis:6379/1'
     depends_on:
       - web
       - redis
     command: >
-      sh -c "celery -A KeRS worker -l info"
+      sh -c "./scripts/wait_for_service web 8000 &&
+             celery -A KeRS worker -l info"
+
   celery-beat:
     build: .
     environment:
-      DATABASE_HOST: 'db'
+      DATABASE_HOST: 'database'
       CELERY_BROKER: 'redis://redis:6379/0'
       CELERY_BACKEND: 'redis://redis:6379/1'
     depends_on:
       - web
       - redis
     command: >
-      sh -c "celery -A KeRS beat -l info --scheduler django_celery_beat.schedulers:DatabaseScheduler"
+      sh -c "./scripts/wait_for_service web 8000 &&
+             celery -A KeRS beat -l info --scheduler django_celery_beat.schedulers:DatabaseScheduler"
+
   redis:
-    image: redis
+    image: redis:latest
+
   # Db stuff
-  db:
-    image: mysql:8.0.21
-    command: --default-authentication-plugin=mysql_native_password
+  database:
+    image: mariadb:10.5.4-focal
     environment:
       MYSQL_ROOT_PASSWORD: example
       MYSQL_DATABASE: kers
@@ -51,6 +56,6 @@ services:
   adminer:
     image: adminer:latest
     depends_on:
-      - db
+      - database
     ports:
       - 8080:8080

scripts/wait_for_service

@@ -0,0 +1,7 @@
+if [ $# -ne 2 ]
+  then
+    echo "Hostname and port of the service was not specified"
+    exit 1
+fi
+
+while ! nc -z $1 $2; do echo "Not yet available, waiting" && sleep 1; done; echo "Done"