Logging request IDs with Tornado https://quanttype.net/posts/2020-02-05-request-id-logging.html
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import contextvars | |
import logging | |
import uuid | |
import tornado.ioloop | |
import tornado.web | |
logger = logging.getLogger(__name__) | |
request_id_var = contextvars.ContextVar("request_id") | |
# Let's have an async function for the sake of demonstration | |
async def generate_number(): | |
logger.info("generate a number") | |
return 4 | |
class MyHandler(tornado.web.RequestHandler): | |
# prepare is called at the beginning of request handling | |
def prepare(self): | |
# If the request headers do not include a request ID, let's generate one. | |
request_id = self.request.headers.get("request-id") or str(uuid.uuid4()) | |
request_id_var.set(request_id) | |
async def get(self): | |
number = await generate_number() | |
self.write(f"Here's a number: {number}") | |
def make_app(): | |
return tornado.web.Application([(r"/", MyHandler),]) | |
class MyFilter(logging.Filter): | |
def filter(self, record): | |
record.request_id = request_id_var.get("-") | |
return True | |
if __name__ == "__main__": | |
logging.basicConfig( | |
format="%(levelname)s %(request_id)s %(message)s", level=logging.INFO | |
) | |
# Log filters do not propagate, but handlers do. Thus we add the filter | |
# to the handlers of the root logger so that the messages of child loggers | |
# get filtered as well. | |
my_filter = MyFilter() | |
for handler in logging.getLogger().handlers: | |
handler.addFilter(my_filter) | |
port = 8000 | |
app = make_app() | |
app.listen(port) | |
logger.info("Listening at http://localhost:%d/", port) | |
tornado.ioloop.IOLoop.current().start() |
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