How To Use An Aiohttp Clientsession With Sanic?
I am trying to understand what is the right way to use aiohttp with Sanic. From aiohttp documentation, I find the following: Don’t create a session per request. Most likely you
Solution 1:
In order to use a single aiohttp.ClientSession
we need to instantiate the session only once and use that specific instance in the rest of the application.
To achieve this we can use a before_server_start
listener which will allow us to create the instance before the app serves the first byte.
from sanic import Sanic
from sanic.response import json
import aiohttp
app = Sanic(__name__)
@app.listener('before_server_start')definit(app, loop):
app.aiohttp_session = aiohttp.ClientSession(loop=loop)
@app.listener('after_server_stop')deffinish(app, loop):
loop.run_until_complete(app.aiohttp_session.close())
loop.close()
@app.route("/")asyncdeftest(request):
"""
Download and serve example JSON
"""
url = "https://api.github.com/repos/channelcat/sanic"asyncwith app.aiohttp_session.get(url) as response:
returnawait response.json()
app.run(host="0.0.0.0", port=8000, workers=2)
Breakdown of the code:
- We are creating an
aiohttp.ClientSession
, passing as argument the loop thatSanic
apps create at the start, avoiding this pitfall in the process. - We store that session in the Sanic
app
. - Finally, we are using this session to make our requests.
Solution 2:
That is essentially what I am doing.
I created a module (interactions.py
) that has, for example a function like this:
asyncdefget(url, headers=None, **kwargs):
asyncwith aiohttp.ClientSession() as session:
log.debug(f'Fetching {url}')
asyncwith session.get(url, headers=headers, ssl=ssl) as response:
try:
returnawait response.json()
except Exception as e:
log.error(f'Unable to complete interaction: {e}')
returnawait response.text()
Then I just await
on that:
results = await interactions.get(url)
I am not sure why that is not the "right way". The session (at least for my needs) can be closed as soon as my request is done.
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