fix: update Prometheus datasource URL and improve Grafana setup logic

makefile

@@ -227,8 +227,8 @@ setup-grafana:
 	{ \
 	echo "Setting up grafana config on host..." ;\
 	mkdir -p /var/data/grafana/provisioning/datasources /var/data/grafana/dashboards ;\
-	cp -n ./swarm/grafana/grafana.ini /var/data/grafana/grafana.ini 2>/dev/null || echo "grafana.ini already exists, skipping" ;\
-	cp -n ./swarm/grafana/provisioning/datasources/prometheus.yml /var/data/grafana/provisioning/datasources/prometheus.yml 2>/dev/null || echo "prometheus datasource already exists, skipping" ;\
+	cmp -s ./swarm/grafana/grafana.ini /var/data/grafana/grafana.ini 2>/dev/null || cp ./swarm/grafana/grafana.ini /var/data/grafana/grafana.ini ;\
+	cmp -s ./swarm/grafana/provisioning/datasources/prometheus.yml /var/data/grafana/provisioning/datasources/prometheus.yml 2>/dev/null || cp ./swarm/grafana/provisioning/datasources/prometheus.yml /var/data/grafana/provisioning/datasources/prometheus.yml ;\
 	}
 deploy-grafana: pull setup-grafana
 	{ \
@@ -250,7 +250,7 @@ setup-prometheus:
 	{ \
 	echo "Setting up prometheus config on host..." ;\
 	mkdir -p /var/data/prometheus ;\
-	cp -n ./swarm/prometheus/prometheus.yml /var/data/prometheus/prometheus.yml 2>/dev/null || echo "prometheus.yml already exists, skipping" ;\
+	cmp -s ./swarm/prometheus/prometheus.yml /var/data/prometheus/prometheus.yml 2>/dev/null || cp ./swarm/prometheus/prometheus.yml /var/data/prometheus/prometheus.yml ;\
 	}
 deploy-monitoring: pull setup-grafana setup-prometheus
 	{ \

swarm/grafana/provisioning/datasources/prometheus.yml

@@ -1,13 +1,13 @@
 # Provisioning config for the Prometheus datasource in Grafana.
-# Both services are on the traefik-public overlay network,
-# so 'prometheus' resolves via Swarm DNS.
+# The service VIP for 'prometheus' on traefik-public is not reliably routing
+# in this stack, so use task DNS to reach the live Prometheus task directly.
 apiVersion: 1
 
 datasources:
   - name: Prometheus
     type: prometheus
     access: proxy
-    url: http://prometheus:9090
+    url: http://tasks.prometheus:9090
     isDefault: true
     editable: true
     jsonData:

swarm/prometheus-grafana.yml

@@ -18,7 +18,6 @@ services:
       - '--web.enable-lifecycle'
     volumes:
       - prometheus_data:/prometheus
-      - /var/data/prometheus/rules:/etc/prometheus/rules:ro
       - /var/data/prometheus/prometheus.yml:/etc/prometheus/prometheus.yml:ro
     networks:
       - traefik-public

swarm/prometheus.yml

@@ -17,7 +17,6 @@ services:
       - '--web.enable-lifecycle'
     volumes:
       - prometheus_data:/prometheus
-      - /var/data/prometheus/rules:/etc/prometheus/rules:ro
       - /var/data/prometheus/prometheus.yml:/etc/prometheus/prometheus.yml:ro
     networks:
       - traefik-public