test: wait for mosquitto before starting server; add mosquitto healthcheck

test/docker-compose.yml

@@ -16,6 +16,8 @@ services:
       - MQTT_TOPIC=lambdaiot
     depends_on:
       - mosquitto
+    # ensure mosquitto is reachable before launching the server
+    command: sh -c "apk add --no-cache netcat-openbsd >/dev/null 2>&1 || true; until nc -z mosquitto 1883; do echo waiting for mosquitto...; sleep 1; done; /usr/local/bin/server"
 
   mosquitto:
     image: eclipse-mosquitto:2.0
@@ -24,6 +26,11 @@ services:
     volumes:
       - mosquitto_data:/mosquitto/data
       - mosquitto_log:/mosquitto/log
+    healthcheck:
+      test: ["CMD", "sh", "-c", "nc -z localhost 1883 || exit 1"]
+      interval: 2s
+      timeout: 2s
+      retries: 10
 
   subscriber:
     image: python:3.11-slim