Handling "X-Request-ID" tracing in flask with logger

flask_tracing_request_id.py

#! /usr/bin/env python3
from flask import Flask, request
# Need python 3.7+
from contextvars import ContextVar
import logging

request_id_context = ContextVar("request_id")

# Flask app
app = Flask(__name__)
@app.route("/")
def hello_world():
  logging.info("Hello, World!")
  return "<p>Hello, World!</p>"

@app.before_request
def before_request():
  if request.headers.get('X-Request-ID') is not None:
    request_id_context.set(request.headers.get('X-Request-ID').strip())

class LoggingFilter(logging.Filter):
  """
  Filter to add request id into the log record.
  This will read the X_REQUEST_ID from request object and set in log record.
  """
  def filter(self, log_record):
    log_record.request_id = request_id_context.get("NA")
    return log_record


if __name__ == "__main__":
  # Setup your logger
  handler = logging.StreamHandler()
  handler.setFormatter(logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(request_id)s - %(message)s"))
  handler.addFilter(LoggingFilter())
  logging.getLogger().addHandler(handler)
  logging.getLogger().setLevel("INFO")

  app.run('0.0.0.0', 5000)

Handing tracing header in flask

This requires python 3.7+. We use contextvars to store the value based on thread.

To start flask server

• Download this file wget https://gist.githubusercontent.com/arulrajnet/f8ed114b5b6bc60823b5e83b47aee139/raw/flask_tracing_request_id.py
• Then python3 flask_tracing_request_id.py
• Then curl -v -H "x-request-id: $(date +%s)" http://localhost:5000/