Flask Sleuth

Spring Cloud Sleuth logging implementation for Flask in Python 2/3.

Purpose

Implement a Spring-style logging format to support interoperability and distributed tracing with Spring applications.

What's in the box?

This project provides:

• Logging in Spring Boot format using standard Python logging.
• Distributed trace information (B3) in Spring Cloud Sleuth format.
• regex.regex.py Regexes that document the log format, which is based on Spring Boot and Spring Cloud Sleuth.
• app.py Python code to generate example log messages.

NB: this repo includes a copy of the B3 code in order to log tracing information.

Usage

Careful design has gone in to making this code as simple as possible to use. To add this to your project, you'll need to copy flask_logging/__init__.py and b3/__init__.py. Once imported, you should be able to use completely standard Python logging:

import logging
import flask_logging
app = Flask("My app")

That should be all you need. Simply importing the flask_logging module calls logging.basicConfig and configures Python logging.

NB basicConfig does nothing once the logging system is initialised. If you currently call basicConfig, you'll need to think about how to work with this.

You can run app.py to see logging in action.

Here are the two intended use cases:

Basic Spring Boot format

logger = logging.getLogger("demo_logger")
logger.setLevel(logging.DEBUG)
logger.debug("Logging without tracing information")

With B3 tracing information (Spring Cloud Sleuth format)

logger = logging.getLogger("demo_logger")
logger.setLevel(logging.DEBUG)
b3.start_span()
logger.debug("Logging with added tracing information")
b3.end_span()

NB You'll likely want to call start_span() and end_span() using Flask.before_request() and Flask.after_request(). See the flask_b3 README for details.