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Python3_aiohttp plugin tutorial

Let's create a plugin based on the python3_aiohttp plugin template. We will called it foo_nodejs.

First, bootstrap the plugin with the command : 

bootstrap_plugin.py create --template=python3_aiohttp foo_aiohttp

Once you have entered this command, you will be asked to fill in some fields to configure and customize your plugin: for now, press [ENTER] to set the default values. The plugin is created in the current directory, inside the directory named foo_aiohttp.

Check this directory, it contains few files, including:

  • main directory: the Python package for your project. Its name is the Python package name you’ll need to use to import anything inside it. This directory contains:
    • application.py: An entry-point for WSGI-compatible web servers to serve your project.

Let's now build the plugin by entering the command from the foo_aiohttp plugin directory:

make develop

Now, you can check your application works by invoking the following URL: http://localhost:18868/foo_aiohttp (you may replace localhost by your remote host if needed). A HTML page must display Hello World from aiohttp app.

Set the debug parameter to 1 (instead of 0) in the [app_...] section of the plugin config.ini file, in order to get an interactive debugger in your browser: check Interactive debugger.

Check the foo_aiohttp/application.py script. It is a basic aiohttp application (app) which create, start the application. It routes all incoming HTTP GET requests to a unique handler which return an "Hello World" HTTP response.

You will also see some calls to start and stop functions and callbacks from metwork_tools module to neatly start and stop the application: When creating the application, you will see MetWork middlewares are passed to the middlewares parameter:

def get_app(timeout=int(os.environ['MFSERV_NGINX_TIMEOUT']) - 2):
    app = web.Application(middlewares=[timeout_middleware_factory(timeout),
                                       mflog_middleware])
    app.router.add_get('/{tail:.*}', handle)
    return app

You can disable some (or all) middlewares by changing (omitting) the middlewares parameter. See aiohttp API

We will extend our "Hello World!" application to handle more types of HTTP requests. Edit the the foo_aiohttp/application.py script as below: 

import sys
import os
from aiohttp import web
from aiohttp_metwork_middlewares import mflog_middleware
from aiohttp_metwork_middlewares import timeout_middleware_factory

app_name = os.environ.get('MFSERV_CURRENT_PLUGIN_NAME', "unknown")

def get_url_prefix():
    return '/{}'.format(app_name)

async def home_get(request):
    log = request['mflog_logger']
    log.info("this is an info message from home_get")
    return web.Response(text="Hello World from a GET request")


async def home_post(request):
    log = request['mflog_logger']
    log.info("this is an info message from home_post")
    return web.Response(text="Hello World from a POST request")

async def pattern(request):
    log = request['mflog_logger']
    log.info("this is an info message from pattern")
    return web.Response(text="Hello World from a Pattern Match")


def get_app(timeout=int(os.environ['MFSERV_NGINX_TIMEOUT']) - 2):
    app = web.Application(middlewares=[timeout_middleware_factory(timeout),
                                       mflog_middleware])
    app.router.add_get(get_url_prefix(), home_get)
    # This responds a POST request for the home url
    app.router.add_post(get_url_prefix(), home_post)
    # This responds a GET request for wxy, waxy, w1234bxy, and so on...
    app.router.add_get(get_url_prefix() + '/{tail:w.*xy}', pattern)
    return app


if __name__ == '__main__':
    if len(sys.argv) == 3:
        web.run_app(get_app(int(sys.argv[2])), path=sys.argv[1])
    elif len(sys.argv) == 2:
        web.run_app(get_app(), path=sys.argv[1])
    else:
        web.run_app(get_app())

Build the plugin with make develop command.

Check your application works by invoking the relevant URLs you added.

You may also doing the same with decorators:

import sys
import os
from aiohttp import web
from aiohttp_metwork_middlewares import mflog_middleware
from aiohttp_metwork_middlewares import timeout_middleware_factory

routes = web.RouteTableDef()
app_name = os.environ.get('MFSERV_CURRENT_PLUGIN_NAME', "unknown")


def get_url_prefix():
    return '/{}'.format(app_name)

@routes.get(get_url_prefix())
async def home_get(request):
    log = request['mflog_logger']
    log.info("this is an info message from home_get")
    return web.Response(text="Hello World from a GET request")

@routes.post(get_url_prefix())
async def home_post(request):
    log = request['mflog_logger']
    log.info("this is an info message from home_post")
    return web.Response(text="Hello World from a POST request")

@routes.get(get_url_prefix() + '/{tail:w.*xy}')
async def pattern(request):
    log = request['mflog_logger']
    log.info("this is an info message from pattern")
    return web.Response(text="Hello World from a Pattern Match")


def get_app(timeout=int(os.environ['MFSERV_NGINX_TIMEOUT']) - 2):
    app = web.Application(middlewares=[timeout_middleware_factory(timeout),
                                       mflog_middleware])
    app.add_routes(routes)
    return app


if __name__ == '__main__':
    if len(sys.argv) == 3:
        web.run_app(get_app(int(sys.argv[2])), path=sys.argv[1])
    elif len(sys.argv) == 2:
        web.run_app(get_app(), path=sys.argv[1])
    else:
        web.run_app(get_app())

See also :