Managed Service for OpenTelemetry:Write trace IDs and span IDs to logs

Java

logging.pattern.level=trace_id=%mdc{trace_id} span_id=%mdc{span_id} %5p

2024-06-26 10:56:31.200 trace_id=8f7ebd8a73f9a8f50e6a00a87a20952a span_id=1b08f18b8858bb9a  INFO 53724 --- [nio-8081-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2024-06-26 10:56:31.201 trace_id=8f7ebd8a73f9a8f50e6a00a87a20952a span_id=1b08f18b8858bb9a  INFO 53724 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2024-06-26 10:56:31.209 trace_id=8f7ebd8a73f9a8f50e6a00a87a20952a span_id=1b08f18b8858bb9a  INFO 53724 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 8 ms
2024-06-26 10:56:31.296 trace_id=8f7ebd8a73f9a8f50e6a00a87a20952a span_id=5743699405074f4e  INFO 53724 --- [nio-8081-exec-1] com.example.httpserver.ot.OTServer       : hello world

Go

OpenTelemetry in Go does not support automatic writing of trace IDs and span IDs to logs. If you do not perform extra development operations such as the following ones, you need to manually record trace IDs and span IDs.

Use logrus

1. Add dependencies.

   import (
       oteltrace "go.opentelemetry.io/otel/trace"
       "github.com/sirupsen/logrus"
   )

2. Create a tool function to extract trace IDs and span IDs from spans and add them to the Logrus log field.

   func LogrusFields(span oteltrace.Span) logrus.Fields {
       return logrus.Fields{
           "trace_id": span.SpanContext().TraceID().String(),
           "span_id": span.SpanContext().SpanID().String(),
       }
   }

3. After a span is created, a log with a trace ID and a span ID is generated.

   ...
   _, span := tracer.Start(ctx, "spanName")
   defer span.End()
   logEntry := logrus.WithFields(LogrusFields(span))
   logEntry.Info("This is an info message with trace and span ID")
   ...

Python

OpenTelemetry in Python supports automatic writing of trace IDs and span IDs to logs. For more information, see OpenTelemetry Logging Instrumentation.

Use logging

1. Set the OTEL_PYTHON_LOG_CORRELATION environment variable to true to enable automatic writing of trace IDs and span IDs to logs.

   export OTEL_PYTHON_LOG_CORRELATION=true

2. Add %(otelTraceID)s and %(otelSpanID)s to the log format. OpenTelemetry automatically replaces %(otelTraceID)s and %(otelSpanID)s in logs with trace IDs and span IDs.

   • The following example shows a log format:

     formatter = logging.Formatter(
         '%(asctime)s %(levelname)s [%(name)s] [%(filename)s:%(lineno)d] [trace_id=%(otelTraceID)s span_id=%(otelSpanID)s resource.service.name=%(otelServiceName)s] - %(message)s'
     )

   • The following example shows a log:

     2024-06-25 10:00:55,494 INFO [app] [app.py:80] [trace_id=70561de6a164ac991bfff2281b7f**** span_id=4b7f3c798460**** resource.service.name=ot-python-demo] - hello world

Operation example

In the following example, a demo application named Helloword is used to show how to automatically write trace IDs and span IDs to logs in Python.

Before you start, make sure that Python and pip are installed. In this example, Python 3.12.4 and pip 24.1.1 are used.

1. Install the Flask framework.

   pip3 install flask

   Expected output:

   Successfully installed Jinja2-3.1.4 MarkupSafe-2.1.5 Werkzeug-3.0.3 blinker-1.8.2 click-8.1.7 flask-3.0.3 itsdangerous-2.2.0

   If information similar to the preceding output is displayed, the installation is successful.

2. Install the required OpenTelemetry Python packages and tools.

   pip3 install opentelemetry-distro \
           opentelemetry-exporter-otlp
   opentelemetry-bootstrap -a install

   Expected output:

   Successfully installed opentelemetry-instrumentation-dbapi-0.46b0
   Successfully installed opentelemetry-instrumentation-requests-0.46b0
   Successfully installed opentelemetry-instrumentation-urllib3-0.46b0

   If information similar to the preceding output is displayed, the installation is successful.

3. Create an application by using the sample code.

   import logging
   from logging.handlers import RotatingFileHandler
   from flask import Flask
   
   import os
   
   app = Flask(__name__)
   
   # Create a formatter that contains the OpenTelemetry context.
   formatter = logging.Formatter(
       '%(asctime)s %(levelname)s [%(name)s] [%(filename)s:%(lineno)d] [trace_id=%(otelTraceID)s span_id=%(otelSpanID)s resource.service.name=%(otelServiceName)s] - %(message)s'
   )
   
   # Create a RotatingFileHandler to write logs to a file.
   # Replace /path/to/app.log with the actual path of the log file.
   file_handler = RotatingFileHandler('/path/to/app.log', maxBytes=10000, backupCount=1)  
   file_handler.setLevel(logging.INFO)
   file_handler.setFormatter(formatter)
   app.logger.addHandler(file_handler)
   
   @app.route('/')
   def hello_world():
       app.logger.info('Hello World!!!')
       return 'Hello, World!'
   
   if __name__ == '__main__':
       app.run()
   

   Run the demo application. Expected output:

   * Running on http://127.0.**.**:5000

   If information similar to the preceding output is displayed, the application deployment is successful.

4. Set environment variables to enable automatic writing of trace IDs and span IDs to logs and use OpenTelemetry to automatically instrument the demo application.

   export OTEL_PYTHON_LOG_CORRELATION=true
   export OTEL_SERVICE_NAME=ot-python-demo
   export OTEL_TRACES_EXPORTER=otlp
   export OTEL_METRICS_EXPORTER=none
   
   # Replace test.py with the actual file name.
   opentelemetry-instrument python3 test.py

5. View the log file. The following example shows a log:

   2024-06-25 10:00:55,494 INFO [app] [test.py:80] [trace_id=70561de6a164ac991bfff2281b7f**** span_id=4b7f3c798460**** resource.service.name=ot-python-demo] - hello world

   In this example, a trace ID and a span ID are recorded in the log.

Bilateral association between traces and Simple Log Service

Associate logs with traces. For more information, see Log association.

Associate traces with logs in Simple Log Service. For more information, see Associate application logs with trace IDs in Simple Log Service.