Simple Python HTTP(S) Server With GET/POST Examples

Mar 20, 2016 13:17 · 889 words · 5 minute read python web

The standard Python library has a built-in module that can be used as minimalistic HTTP/HTTPS web server. It provides support of the protocol and allows you to extend capabilities by subclassing.

Serve static HTML/CSS files to outside world can be very helpful and handy in many real life situations. For example, to show a client HTML pages you’ve created or stub an API by creating a static file.

Example of static HTTP web server

Yet another purpose that static web server can serve is to create a dummy API by creating json or/and xml files. The structure of resources organized in sub-folders will provide RESTful-like URLs. E.g. /users/all.json.json may contain dummy records of users. This approach even faster then creating, for instance, a Flask application. No database required, works everywhere.

To download data from a remote server. Let’s say there are some difficulties with scp command. It is possible to run simple server on the remote machine and download necessary contents via HTTP.

Python 3.x

python3 -m http.server 8000 --bind 127.0.0.1 
Both port and bind address are optional. For more details, please read the official docs.

Python 2.x

python -m SimpleHTTPServer 8000
Python 2.x can only accept port as a parameter Bind address parameter is not available. Python 2.x Docs.

In both cases contents of the current folder will be accessible via http://127.0.0.1:8000

Example with SSL support

To run secure HTTPs server create a following module:

Python 3.x

from http.server import HTTPServer, BaseHTTPRequestHandler
import ssl


httpd = HTTPServer(('localhost', 4443), BaseHTTPRequestHandler)

httpd.socket = ssl.wrap_socket (httpd.socket, 
        keyfile="path/to/key.pem", 
        certfile='path/to/cert.pem', server_side=True)

httpd.serve_forever()

Python 2.x

import BaseHTTPServer, SimpleHTTPServer
import ssl


httpd = BaseHTTPServer.HTTPServer(('localhost', 4443),
        SimpleHTTPServer.SimpleHTTPRequestHandler)

httpd.socket = ssl.wrap_socket (httpd.socket,
        keyfile="path/tp/key.pem",
        certfile='path/to/cert.pem', server_side=True)

httpd.serve_forever()

To generate key and cert files with OpenSSL use following command

openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365

Further examples will assume Python 3.5+ as an interpreter.

Advanced Python HTTP server

Let’s make our web server a little more advanced by handling requests.

do_GET

Consider the following code:

from http.server import HTTPServer, BaseHTTPRequestHandler


class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):

    def do_GET(self):
        self.send_response(200)
        self.end_headers()
        self.wfile.write(b'Hello, world!')


httpd = HTTPServer(('localhost', 8000), SimpleHTTPRequestHandler)
httpd.serve_forever()

This is a very trivial HTTP server that responds Hello, world! to the requester. Note, that self.send_response(200) and self.end_headers() are mandatory, otherwise the response wont be considered as valid. We can check that it actually works by sending a request using HTTPie:

$ http http://127.0.0.1:8000

HTTP/1.0 200 OK
Date: Sun, 25 Feb 2018 17:26:20 GMT
Server: BaseHTTP/0.6 Python/3.6.1

Hello, world!

Note, that self.wfile is a file like object, thus expects a byte-like objects to the write function. Another way of feeding the wfile is by using BytesIO object (see example below).

do_POST

Let’s handle a POST request now. Full example:

from http.server import HTTPServer, BaseHTTPRequestHandler

from io import BytesIO


class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):

    def do_GET(self):
        self.send_response(200)
        self.end_headers()
        self.wfile.write(b'Hello, world!')

    def do_POST(self):
        content_length = int(self.headers['Content-Length'])
        body = self.rfile.read(content_length)
        self.send_response(200)
        self.end_headers()
        response = BytesIO()
        response.write(b'This is POST request. ')
        response.write(b'Received: ')
        response.write(body)
        self.wfile.write(response.getvalue())


httpd = HTTPServer(('localhost', 8000), SimpleHTTPRequestHandler)
httpd.serve_forever()

The request body can be accessed via self.rfile. It is a BufferedReader so read([size]) method should be executed in order to get the contents. Note, that size should be explicitly passed to the function, otherwise the request will hang and never end.

This is why obtaining content_length is necessary. It could be retrieved via self.headers and converted into an integer. An example above just prints back whatever he receives, like follows:

http http://127.0.0.1:8000 key=value
HTTP/1.0 200 OK
Date: Sun, 25 Feb 2018 17:46:06 GMT
Server: BaseHTTP/0.6 Python/3.6.1

This is POST request. Received: {"key": "value"} 

You may consider to parse the JSON if you like.

Twiseted as a simple web HTTP(S) server

Another great example of a web server is Twiseted. Clearly, it is much faster than one built in Python and provides lots of features out of the box. It supports SSL without a need to write a single line of code. It supports both Python 3.x and 2.x.

Installation

pip install twisted

Usage

To run a twisted as a web server to serve current directory:

twistd -no web --path

You will see the output like follows:

(.venv) andrey@work$ ~/Projects/test_app  twistd -no web --path=.
2016-10-23T19:05:02+0300 [twisted.scripts._twistd_unix.UnixAppLogger#info] twistd 16.4.1 (/Users/andrey/Projects/anvileight/.venv/bin/python3.5 3.5.1) starting up.
2016-10-23T19:05:02+0300 [twisted.scripts._twistd_unix.UnixAppLogger#info] reactor class: twisted.internet.selectreactor.SelectReactor.
2016-10-23T19:05:02+0300 [-] Site starting on 8080
2016-10-23T19:05:02+0300 [twisted.web.server.Site#info] Starting factory <twisted.web.server.Site object at 0x110b96c50>

Options

-n, –nodaemon don’t daemonize, don’t use default umask of 0077

-o, –no_save do not save state on shutdown

–path= is either a specific file or a directory to be set as the root of the web server. Use this if you have a directory full of HTML, cgi, epy, or rpy files or any other files that you want to be

Commands

web A general-purpose web server which can serve from a filesystem or application resource.

If you are looking for HTTPS and SSL support, consider the following options:

–https= Port to listen on for Secure HTTP.

-c, –certificate= SSL certificate to use for HTTPS. [default: server.pem]

-k, –privkey= SSL certificate to use for HTTPS. [default: server.pem]

Docker Example

Here are an example of Dockerfile I use to serve simple html pages to outside world.

FROM python:3.5

VOLUME ["/code"]
ADD . /code
WORKDIR /code

EXPOSE 5000
CMD ["python", "-m", "http.server", "5000"]

It is possible to write custom handlers and extend the basic functionality. Including creating HTTPS server etc. Find official documentation for python 3 http server is here. Python 2 documentation is here

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