• If you are collecting application logs from file, ensure you emit the trace_id and span_id to those logs.
• Once you have trace_id and span_id in your logs, parse them using the pipelines trace parser. See documentation here.

The best way to do this is using Logs Pipeline. Refer to:

• Logs Pipeline Introduction
• Parse JSON logs with Pipelines

If you have a application/service which is emitting similar kind of logs but there are multiple instances of it running on different hosts you can identify them by adding a resource attribute.

There are different ways to add a resource attribute.

1. By passing it as an environment variable if you are using the opentelemetry SDK or auto-instrumentation

   OTEL_RESOURCE_ATTRIBUTES=service.name=<service_name>,host.name=<host_name>
   

   Replace the value of <service_name> with the actual service name and <host_name> with the actual hostname
2. If you have a otel collector running on each host you can add a processor to add the hostname.

   processors:
       resource/add_hostname:
           attributes:
               - key: host.name
                 value: <host_name>
                 action: upsert
   ...
   service:
       logs:
           processors: [resource/add_hostname, batch]
   

   replace the value of <host_name> with the actual hostname

• Add a console exporter at the application level (if using SDK) or at the local collector level.
• If the issue persists, reach out to us via chatbox at the bottom right corner of your SigNoz Cloud interface.

You can get your mdc attributes by using the [appender settings][def] and passing it as -D<property>=<value> format.

For example, for logback use:
otel.instrumentation.logback-appender.experimental.capture-mdc-attributes=*
For log4j use:
otel.instrumentation.log4j-appender.experimental.capture-mdc-attributes=*
See [this documentation][def] for more system properties.