Add healthcheck & bump compose version

compose.yml

@@ -1,4 +1,4 @@
-version: '3.3'
+version: '3.8'
 
 services:
   app:
@@ -11,7 +11,16 @@ services:
     networks:
       - net
       - proxy
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8080"]
+      interval: 30s
+      timeout: 10s
+      retries: 10
+      start_period: 1m
     deploy:
+      update_config:
+        failure_action: rollback
+        order: start-first
       resources:
         limits:
           cpus: '0.50'