====== WebAPI ======

Let's try to make a quick win. We have to make a Proof Of Concept about something and writing a Web RestFul API is a good candidate.


===== Request =====

All Windows laptops in your company are supposed to execute a script every day. However you have a lot of tickets that may be explained by the fact that this daily script is not executed or too long and raises a kind of timeout.

Your idea is to log when the script starts and when it ends. A good one! However you have no idea how to quickly centralize these log files from all laptops. Why not a Web RestFul API? :-)

Before going further: yes I know that a lot of solutions may solve this issue but the target is to make the POC in less than one hour. As I used to develop Web Restful API then it is my choice.

===== Architecture =====

{{ :en:python:web-api.png?600 |Architecture WebAPI}}

{{ :en:python:web-api.dia |Source DIA}}
===== Client side =====

From client side, we are going to use Powershell command as it is native to Windows 10.

<file powershell client_side.ps1 >
# init
$who=whoami
$computer=hostname
$server="my-server.domain.com"

# before the main command, let's call the API
Invoke-WebRequest ("http://{2}:5000/my_command/start/{0}/{1}" -f ($who -replace "\\", "@"), $computer, $server) -Method POST

# main command
my_action

# after the main command, let's call the API
Invoke-WebRequest ("http://{2}:5000/my_command/end/{0}/{1}" -f ($who -replace "\\", "@"), $computer, $server) -Method POST

</file>

API returns something like this:

<code>
StatusCode        : 201
StatusDescription : Created
Content           : {"user": "my_user", "action": "start", "ip_remote": "0.1.2.3", "computer":
                    "my_computer"}

RawContent        : HTTP/1.1 201 Created
                    Connection: close
                    Content-Length: 115
                    Content-Type: application/json
                    Date: Tue, 26 May 2020 13:46:28 GMT
                    Server: gunicorn/20.0.4

                    {"user": "my_user", "action": "star...
Forms             : {}
Headers           : {[Connection, close], [Content-Length, 115], [Content-Type, application/json], [Date, Tue, 26 May 2020 13:46:28
                    GMT]...}
Images            : {}
InputFields       : {}
Links             : {}
ParsedHtml        : mshtml.HTMLDocumentClass
RawContentLength  : 115
</code>

If you are running linux laptop you can adapt the script with curl.

<code bash>
curl -i -XPOST --silent http://localhost:5000/my_command/start/toto/computer
HTTP/1.1 201 CREATED
Server: gunicorn
Date: Fri, 16 Apr 2021 03:07:27 GMT
Connection: close
Content-Type: application/json
Content-Length: 86

{"user": "toto", "action": "start", "ip_remote": "127.0.0.1", "computer": "computer"}
</code>
===== Server side =====

==== Run it ====


<code bash>
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt
gunicorn  --bind 0.0.0.0:5000 wsgi:app
</code>
==== Logger ====

<file python logger.py>
import logging

logger = logging.getLogger('api')
logger.setLevel(logging.DEBUG)
# create file handler which logs even debug messages
fh = logging.FileHandler('api.log')
fh.setLevel(logging.INFO)
# create console handler with a higher log level
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)
# create formatter and add it to the handlers
formatter = logging.Formatter(
    '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
)
ch.setFormatter(formatter)
fh.setFormatter(formatter)
# add the handlers to logger
logger.addHandler(ch)
logger.addHandler(fh)
</file>

==== WSGI ====

<file python wsgi.py>
from api import app

if __name__ == "__main__":
    app.run()
</file>
==== API ====

<file python api.py>
from flask import Flask, request
from flask_restful import Resource, Api
from logger import logger


app = Flask(__name__)
api = Api(app)


class HelloWorld(Resource):
    def post(self, user, action, computer):
        logger.info(f"{computer},{action},{user},{request.remote_addr}")
        return {
            "user": user,
            "action": action,
            "ip_remote": request.remote_addr,
            "computer": computer
        }


api.add_resource(
    HelloWorld,
    '/my_command/<string:action>/<string:user>/<string:computer>'
)

if __name__ == '__main__':
    app.run(debug=True, host="0.0.0.0")
</file>

==== Requirements ====

<file text requirements.txt>
flake8
flask_restful
gunicorn
</file>