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https://github.com/workable/flask-log-request-id

Flask extension to track and log Request-ID headers produced by PaaS like Heroku and load balancers like Amazon ELB
https://github.com/workable/flask-log-request-id

celery flask python request-id web

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Flask extension to track and log Request-ID headers produced by PaaS like Heroku and load balancers like Amazon ELB

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README 

        

# Flask-Log-Request-Id



[![CircleCI](https://img.shields.io/circleci/project/github/Workable/flask-log-request-id.svg)](https://circleci.com/gh/Workable/flask-log-request-id)



**Flask-Log-Request-Id** is an extension for [Flask](http://flask.pocoo.org/) that can parse and handle the

request-id sent by request processors like [Amazon ELB](http://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-request-tracing.html),

[Heroku Request-ID](https://devcenter.heroku.com/articles/http-request-id) or any multi-tier infrastructure as the one used

at microservices. A common usage scenario is to inject the request_id in the logging system so that all log records,

even those emitted by third party libraries, have attached the request_id that initiated their call. This can

greatly improve tracing and debugging of problems.



## Installation



The easiest way to install it is using ``pip`` from PyPI



```bash

pip install flask-log-request-id

```



## Usage



Flask-Log-Request-Id provides the `current_request_id()` function which can be used at any time to get the request

id of the initiated execution chain.



### Example 1: Parse request id and print to stdout

```python

from flask_log_request_id import RequestID, current_request_id



[...]



RequestID(app)



@app.route('/')

def hello():

    print('Current request id: {}'.format(current_request_id()))

```



### Example 2: Parse request id and send it to to logging



In the following example, we will use the `RequestIDLogFilter` to inject the request id on all log events, and

a custom formatter to print this information. If all these sounds unfamiliar please take a look at [python's logging

system](https://docs.python.org/3/library/logging.html)



```python

import logging

import logging.config

from random import randint

from flask import Flask

from flask_log_request_id import RequestID, RequestIDLogFilter



def generic_add(a, b):

    """Simple function to add two numbers that is not aware of the request id"""

    logging.debug('Called generic_add({}, {})'.format(a, b))

    return a + b



app = Flask(__name__)

RequestID(app)



# Setup logging

handler = logging.StreamHandler()

handler.setFormatter(logging.Formatter("%(asctime)s - %(name)s - level=%(levelname)s - request_id=%(request_id)s - %(message)s"))

handler.addFilter(RequestIDLogFilter())  # << Add request id contextual filter

logging.getLogger().addHandler(handler)



@app.route('/')

def index():

    a, b = randint(1, 15), randint(1, 15)

    logging.info('Adding two random numbers {} {}'.format(a, b))

    return str(generic_add(a, b))

```



The above will output the following log entries:



```

2017-07-25 16:15:25,912 - __main__ - level=INFO - request_id=7ff2946c-efe0-4c51-b337-fcdcdfe8397b - Adding two random numbers 11 14

2017-07-25 16:15:25,913 - __main__ - level=DEBUG - request_id=7ff2946c-efe0-4c51-b337-fcdcdfe8397b - Called generic_add(11, 14)

2017-07-25 16:15:25,913 - werkzeug - level=INFO - request_id=None - 127.0.0.1 - - [25/Jul/2017 16:15:25] "GET / HTTP/1.1" 200 -

```



### Example 3: Forward request_id to celery tasks



Flask-Log-Request-Id comes with extras to forward the context of current request_id to the workers of celery tasks.

In order to use this feature you need to enable the celery plugin and configure the `Celery` instance. Then you can

use `current_request_id()` from inside your worker



```python

from flask_log_request_id.extras.celery import enable_request_id_propagation

from flask_log_request_id import current_request_id

from celery.app import Celery

import logging



celery = Celery()

enable_request_id_propagation(celery)  # << This step here is critical to propagate request-id to workers



app = Flask()



@celery.task()

def generic_add(a, b):

    """Simple function to add two numbers that is not aware of the request id"""



    logging.debug('Called generic_add({}, {}) from request_id: {}'.format(a, b, current_request_id()))

    return a + b



@app.route('/')

def index():

    a, b = randint(1, 15), randint(1, 15)

    logging.info('Adding two random numbers {} {}'.format(a, b))

    return str(generic_add.delay(a, b))  # Calling the task here, will forward the request id to the workers

```



You can follow the same logging strategy for both web application and workers using the `RequestIDLogFilter` as shown in

example 1 and 2.



### Example 4: If you want to return request id in response



This will be useful while integrating with frontend where in you can get the request id from the response (be it 400 or 500) and then trace the request in logs.



```python

from flask_log_request_id import current_request_id



@app.after_request

def append_request_id(response):

    response.headers.add('X-REQUEST-ID', current_request_id())

    return response

```



## Configuration



The following parameters can be configured through Flask's configuration system:



| Configuration Name | Description |

| ------------------ | ----------- |

| **LOG_REQUEST_ID_GENERATE_IF_NOT_FOUND**| In case the request does not hold any request id, the extension will generate one. Otherwise `current_request_id` will return None. |

| **LOG_REQUEST_ID_LOG_ALL_REQUESTS** | If True, it will emit a log event at the request containing all the details as `werkzeug` would done along with the `request_id` . |

| **LOG_REQUEST_ID_G_OBJECT_ATTRIBUTE** | This is the attribute of `Flask.g` object to store the current request id. Should be changed only if there is a problem. Use `current_request_id()` to fetch the current id. |



## License



See the [LICENSE](LICENSE.md) file for license rights and limitations (MIT).