Add hostname to default tracing scope

ai_web_common/flask_ai/tracing.py

 import json
 import os
+import socket
 
 from opentelemetry import trace
 from opentelemetry.exporter.zipkin.json import ZipkinExporter
 from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import BatchSpanProcessor
-from opentelemetry.sdk.resources import SERVICE_NAME, Resource
+from opentelemetry.sdk.resources import SERVICE_NAME, HOST_NAME, Resource
 
 
 tracing_config_file = os.getenv('TRACING_CONFIG', '/etc/tracing/client.conf')
@@ -22,6 +23,7 @@ def setup_tracing(service_name):
 
     resource = Resource(attributes={
         SERVICE_NAME: service_name,
+        HOST_NAME: socket.gethostname(),
     })
 
     zipkin_exporter = ZipkinExporter(endpoint=config['report_url'])