Push API & Websockets

tiltti · December 21, 2020, 7:44pm

Hi,

I'm back with my silly project on displaying statuses via Python websocket API so I can show something going on in my big screen attached totally unnecessarily to my OctoPi setup next to the printer.

However since I last made a progress on this API it did work and I managed to receive all GCODE commands via the push, but now I can't get it to work at all.

I saw @Fabian 's post on the authentication needed to be double-wrapped in json but even that does not work. I am also confused whether an additional header is needed for web-socket in top of the authentication message?

There was a reference to documentation on messaging @foosel directly in case someone is planning on using this API and get the latest plans. Well, here we go I guess

So the question is: how to do the authentication with Python3 to the PUSH API via websocket using the websocket-client library and get the GCODE notifications (or anything for that matter) after socket has been initiated?

Cheers

PrintedWeezl · December 21, 2020, 8:36pm

I can't help you with your question - I just want to inform you that @foosel is on vacation right now. She will be back approximately around the 10th of January.

jneilliii · December 21, 2020, 9:17pm

I posted in the other thread, but I think you might just be missing the API auth process that needs to happen ahead of the websocket auth, in order to get a session key.

Fabian · December 21, 2020, 9:28pm

The code I used is public, you can see it at the following address:

github.com

fabian-h/gcode-viewer/blob/5f9b33f63a602893b1864ca401853a77e35a709c/src/app/OctoprintConnection.ts

/* 
Copyright 2019 Fabian Hiller

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License. 
*/

import { observable, action } from "mobx";

export default class OctoprintConnection {
  // http://sockjs.github.io/sockjs-protocol/sockjs-protocol-0.3.3.html#section-37

This file has been truncated. show original

Line 45 is the most important one where the authentication is done.

It's Javascript, and I haven't done anything there in a while, so I can't guarantee that this code works in recent Octoprint versions.

My experience is with a browser client, which reacts very sensitively to stuff like CORS or mixed content (using unencrypted websockets from an encrypted page). This should be less problematic in a Python client, but I'd still try both the ws: and the wss: version, in case one version is not allowed. You might also run into issues with self-signed certificates, in which case you either need to disable certificate validation in Python or use a certifate that your computer will regard as valid.

tiltti · December 22, 2020, 4:58am

Thanks for the heads up Likewise I am on holiday until January, but in my case this is the time I have finally time for my hobby projects from work

Fishpig · December 23, 2020, 4:06pm

Wait what.....Foosel is a lady?
I totally did not know that!

jneilliii · December 23, 2020, 7:17pm

lol, you've never watched an octoprint video...

Ewald_Ikemann · December 23, 2020, 7:25pm

tiltti · January 3, 2021, 4:10pm

Here I am, back from my own holidays eager to see how my 3 new replies to the thread help me onwards with my problem, but all I see was a discovery of Foosel's gender

Anyway, couldn't get Fabian's code to work with my python version, so still something missing. Will give it another look next week.

tiltti · January 3, 2021, 5:25pm

Well, I put some effort to this now after sauna (which always helps), and managed to get this working!

Essentially I guess I was getting mixed with different tokens and in what form to send them, of which finally the following snippet worked.

Especially the format of auth_message was the key: use username + session token. Nothing else worked. I'm sure there is a prettier way but if someone else is stuck with this, here's one way of getting it work.

Cheers.

import websocket, json, requests

try:
    import thread
except ImportError:
    import _thread as thread
import time

HOST = "ws://octopi/sockjs/websocket"

def on_open(ws):
    auth_message = "{ \"auth\": \"xxx:"+session+"\" }"
    ws.send(auth_message)

def on_message(ws, message):
    print("Incoming message: ")
    print(message)

def on_error(ws, error):
    print(error)

def on_close(ws):
    print("Closing Socket...")

if __name__ == "__main__":
    logindata = { 'user': 'xxx', 'pass': 'yyy' }
    r = requests.post('http://octopi:80/api/login', json=logindata, verify=False)
    data = r.json()
    session = data['session']
    websocket.enableTrace(True)
    ws = websocket.WebSocketApp(HOST,
        on_open = on_open,
        on_message = on_message,
        on_error = on_error,
        on_close = on_close)
    ws.run_forever()```

pj298 · January 21, 2021, 9:04am

I wanted to do something similar and spent a little bit of time looking into it, but decide to search if someone else had already done it and was very pleased to see this . turns out I forgot the need to authenticate lol. so thanks!

Here is the prettier way how to send the auth message (works for me using this package https://github.com/websocket-client/websocket-client)

auth_message = json.dumps({"auth": f"{user}:{session}"})

I suggest setting the user name variable, so that you can use it here and later on when you post the logindata.

Did you have plans to send messages to the websocket? That's what I want to do next if I get time to look into.