spin up a simple web server that prints post data to console

Question

I've found a number of simple web servers in python that will spin up a quick server and respond to requests simply. What I need is a server that won't just print the IP address, timestamp, method, and response code of each request (127.0.0.1 - - [28/Aug/2017 10:42:11] "POST / HTTP/1.1" 200 -), but also, if a POST request, I need it to print out the POST data.

So for example, if I send a POST request with {"foo":"bar"} in the body of the message, I want the server to print 127.0.0.1 - - [28/Aug/2017 10:42:11] "POST / HTTP/1.1" 200 - {"foo":"bar"} to the console before responding.

I'm not sure how to modify any of the linked options above to do this. If there's another simple option, that would work as well.

What kind of data? Just JSON? Form? File? Anything specific, or all of the above? — scnerd, Aug 28 '17 at 14:58
Web.py using [this answer?](https://stackoverflow.com/a/33771012/2759780) Printing instead of returning the data. — atwalsh, Aug 28 '17 at 15:26

scnerd · Accepted Answer · 2017-08-28T16:00:05.887

To just print out whatever JSON gets sent to a server, build yourself a basic catch-all endpoint and just print the JSON from it. In flask, this looks like the following:

import logging
from flask import Flask, request
app = Flask(__name__)

@app.route('/', methods=['POST', 'GET'], defaults={'path': ''})
@app.route('/<path:path>', methods=['POST', 'GET'])
def index(path):
    print("HTTP {} to URL /{} received JSON {}".format(request.method, path, request.get_json()))
    return "True"

Here's my calls to the server:

In [15]: requests.post('http://localhost:5000/', json={'a': 1})
Out[15]: <Response [200]>

In [16]: requests.post('http://localhost:5000/some/endpoint', json={'a': 1})
Out[16]: <Response [200]>

In [17]: requests.get('http://localhost:5000/', json={'a': 1})
Out[17]: <Response [200]>

Here's the server output:

In [7]: app.run(host='0.0.0.0')
 * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)
HTTP POST to URL / received JSON {'a': 1}
127.0.0.1 - - [28/Aug/2017 11:57:49] "POST / HTTP/1.1" 200 -
HTTP POST to URL /some/endpoint received JSON {'a': 1}
127.0.0.1 - - [28/Aug/2017 11:57:51] "POST /some/endpoint HTTP/1.1" 200 -
HTTP GET to URL / received JSON {'a': 1}
127.0.0.1 - - [28/Aug/2017 11:57:55] "GET / HTTP/1.1" 200 -

Original Answer

A simple decorator should do the trick:

from flask import Flask, request
app = Flask(__name__)

def print_if_post(*args, **kwargs):
    def inner_decorator(f):
        def inner(*args, **kwargs):
            if request.method == 'POST':
                json = request.get_json()
                print("JSON Data: {}".format(json))

            return f(*args, **kwargs)

        return app.route(*args, **kwargs)(inner)
    return inner_decorator

This decorator will function exactly like app.route, but will print any JSON data sent to its endpoint:

@print_if_post('/', methods=['POST', 'GET'])
def index():
    return "True"

Called with the following code:

In [4]: requests.get('http://localhost:5000/')
Out[4]: <Response [200]>

In [5]: requests.post('http://localhost:5000/', json={'a': 1})
Out[5]: <Response [200]>

Server outputs:

In [2]: app.run(host='0.0.0.0')
 * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)
127.0.0.1 - - [28/Aug/2017 11:03:11] "GET / HTTP/1.1" 200 -
JSON Data: {'a': 1}
127.0.0.1 - - [28/Aug/2017 11:03:23] "POST / HTTP/1.1" 200 -

Like the examples that you link, with [some help from here](https://stackoverflow.com/questions/4233218/python-basehttprequesthandler-post-variables), you may be able to write a minimal server that parses and prints the JSON data in POST requests. Without more details about the server you're trying to write, I'm not sure I can give you a good answer. Are you mainly trying to serve files? If so, why do you care about JSON POST data? Are you writing a basic web application? If so, why aren't you using a more complete server like flask, django, or web.py (as per @atwalsh04)? — scnerd, Aug 28 '17 at 15:35
I'm literally trying to write a server that accepts requests, prints the POST data to the console, if there is any, responds with a 20X, and does absolutely nothing else. The point is to monitor what kinds of requests are being sent by another application I wrote. — ewok, Aug 28 '17 at 15:41
Just use Flask or Web.py like suggested then. It hides a lot of the "server" crap, and lets you just write the logic you want. If dependencies are really not an option, you're probably going to have a bit of a tough time. I'll edit the answer with a more general suggestion for that use case. — scnerd, Aug 28 '17 at 15:52

spin up a simple web server that prints post data to console

1 Answers1

Original Answer