问题描述
在上篇博文“【Azure 应用服务】App Service for Linux 中实现 WebSocket 功能 (Python SocketIO)”中，实现了通过 HTTP 方式访问部署在Azure App Service For Linux上的Python Flask Web Socket项目, 但是当使用HTTPS访问时候，socket.io所发送的GET请求都能正常。
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但是POST请求全部返回400 Bad Request
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那么，如何来解决并实现HTTPS呢？
问题解决
使用 eventlet.monkey_patch() ： 猴子补丁，在运行时动态修改已有的代码，而不需要修改原始代码。对应 “模块运行时替换的功能” 来进行理解。
- Monkey patch就是在运行时对已有的代码进行修改，达到hot patch的目的。
- Eventlet中大量使用了该技巧，以替换标准库中的组件，比如socket。
在创建socketio对象时候，指定使用eventlet模块，然后设置cors_allowed_origins为*。
socketio = SocketIO(app, async_mode="eventlet",cors_allowed_origins='*')
一个简单的Socket Test项目（服务端+客户端）实例代码如下：
pythonsockettest(Folder Name)
----templates
--------index.html
----app.py
----requirements.txt
Templates/Index.html
<!DOCTYPE HTML>
<html>
<head>
<title>Socket-Test</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/3.1.3/socket.io.min.js"></script>
<script type="text/javascript" charset="utf-8">
$(document).ready(function() {
namespace = '/test';
var socket = io(namespace);
socket.on('connect', function() {
socket.emit('my_event', {data: 'connected to the SocketServer...'});
});
socket.on('my_response', function(msg, cb) {
$('#log').append('<br>' + $('<div/>').text('logs #' + msg.count + ': ' + msg.data).html());
if (cb)
cb();
});
$('form#emit').submit(function(event) {
socket.emit('my_event', {data: $('#emit_data').val()});
return false;
});
$('form#broadcast').submit(function(event) {
socket.emit('my_broadcast_event', {data: $('#broadcast_data').val()});
return false;
});
$('form#disconnect').submit(function(event) {
socket.emit('disconnect_request');
return false;
});
});
</script>
</head>
<body style="background-color:white;">
<h1 style="background-color:white;">Socket</h1>
<form id="emit" method="POST" action='#'>
<input type="text" name="emit_data" id="emit_data" placeholder="Message">
<input type="submit" value="Send Message">
</form>
<form id="broadcast" method="POST" action='#'>
<input type="text" name="broadcast_data" id="broadcast_data" placeholder="Message">
<input type="submit" value="Send Broadcast Message">
</form>
<form id="disconnect" method="POST" action="#">
<input type="submit" value="Disconnect Server">
</form>
<h2 style="background-color:white;">Logs</h2>
<div id="log" ></div>
</body>
</html>
app.py
import eventlet
eventlet.monkey_patch()
from flask import Flask, render_template, session, copy_current_request_context
from flask_socketio import SocketIO, emit, disconnect
from threading import Lock
import os
async_mode = None
app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
## For http
#socketio = SocketIO(app, async_mode=async_mode)
## For https
socketio = SocketIO(app, async_mode="eventlet",cors_allowed_origins='*')
thread = None
thread_lock = Lock()
## Used by App Service For linux
PORT = os.environ["PORT"]
serverIP = "0.0.0.0"
# # Used by Local debug.
# PORT = 5000
# serverIP = "127.0.0.1"
@app.route('/')
def index():
return render_template('index.html', async_mode=socketio.async_mode)
@socketio.on('my_event', namespace='/test')
def test_message(message):
print('receive message:' + message['data'],)
session['receive_count'] = session.get('receive_count', 0) + 1
emit('my_response',
{'data': message['data'], 'count': session['receive_count']})
@socketio.on('my_broadcast_event', namespace='/test')
def test_broadcast_message(message):
print('broadcast message:' + message['data'],)
session['receive_count'] = session.get('receive_count', 0) + 1
emit('my_response',
{'data': message['data'], 'count': session['receive_count']},
broadcast=True)
@socketio.on('disconnect_request', namespace='/test')
def disconnect_request():
@copy_current_request_context
def can_disconnect():
disconnect()
session['receive_count'] = session.get('receive_count', 0) + 1
emit('my_response',
{'data': 'Disconnected!', 'count': session['receive_count']},
callback=can_disconnect)
if __name__ == '__main__':
socketio.run(app,port=PORT, host=serverIP, debug=True)
print('socket io start')
requirements.txt
Flask==2.0.2
Flask-SocketIO==5.1.1
eventlet==0.30.2
部署在Azure App Service后，需要设置启动命令：
gunicorn --bind=0.0.0.0 --timeout 600 --worker-class "eventlet" app:app
配置方法可见：https://www.cnblogs.com/lulight/p/15501015.html （第五段：修改App Service的启动命令）
附录：部署上Azure App的代码
#设置登录环境为中国区Azure
az cloud set -n AzureChinaCloud
az login
#部署代码，如果pythonlinuxwebsocket01不存在，则自动创建定价层位B1的App Service
az webapp up --sku B1 --name pythonlinuxwebsocket01
测试效果
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遇见的问题
1： eventlet worker requires eventlet 0.24.1 or higher
2021-12-14T03:31:30.581051185Z Error: class uri 'eventlet' invalid or not found:
2021-12-14T03:31:30.581056185Z
2021-12-14T03:31:30.581059786Z [Traceback (most recent call last):
2021-12-14T03:31:30.581063086Z File "/opt/python/3.7.9/lib/python3.7/site-packages/gunicorn/workers/geventlet.py", line 10, in <module>
2021-12-14T03:31:30.581067386Z import eventlet
2021-12-14T03:31:30.581070686Z ModuleNotFoundError: No module named 'eventlet'
2021-12-14T03:31:30.581073986Z
2021-12-14T03:31:30.581077187Z During handling of the above exception, another exception occurred:
2021-12-14T03:31:30.581081587Z
2021-12-14T03:31:30.581084787Z Traceback (most recent call last):
2021-12-14T03:31:30.581088187Z File "/opt/python/3.7.9/lib/python3.7/site-packages/gunicorn/util.py", line 99, in load_class
2021-12-14T03:31:30.581107988Z mod = importlib.import_module('.'.join(components))
2021-12-14T03:31:30.581111389Z File "/opt/python/3.7.9/lib/python3.7/importlib/__init__.py", line 127, in import_module
2021-12-14T03:31:30.581114489Z return _bootstrap._gcd_import(name[level:], package, level)
2021-12-14T03:31:30.581117589Z File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
2021-12-14T03:31:30.581120689Z File "<frozen importlib._bootstrap>", line 983, in _find_and_load
2021-12-14T03:31:30.581123789Z File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
2021-12-14T03:31:30.581126890Z File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
2021-12-14T03:31:30.581130090Z File "<frozen importlib._bootstrap_external>", line 728, in exec_module
2021-12-14T03:31:30.581133190Z File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
2021-12-14T03:31:30.581136290Z File "/opt/python/3.7.9/lib/python3.7/site-packages/gunicorn/workers/geventlet.py", line 12, in <module>
2021-12-14T03:31:30.581139490Z raise RuntimeError("eventlet worker requires eventlet 0.24.1 or higher")
2021-12-14T03:31:30.581142690Z RuntimeError: eventlet worker requires eventlet 0.24.1 or higher
2：cannot import name 'ALREADY_HANDLED' from 'eventlet.wsgi'
2021-12-14T05:14:28.142182566Z Error: class uri 'eventlet' invalid or not found:
2021-12-14T05:14:28.142189566Z
2021-12-14T05:14:28.142194867Z [Traceback (most recent call last):
2021-12-14T05:14:28.142199767Z File "/opt/python/3.7.9/lib/python3.7/site-packages/gunicorn/util.py", line 99, in load_class
2021-12-14T05:14:28.142212168Z mod = importlib.import_module('.'.join(components))
2021-12-14T05:14:28.142217368Z File "/opt/python/3.7.9/lib/python3.7/importlib/__init__.py", line 127, in import_module
2021-12-14T05:14:28.142222569Z return _bootstrap._gcd_import(name[level:], package, level)
2021-12-14T05:14:28.142239170Z File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
2021-12-14T05:14:28.142244870Z File "<frozen importlib._bootstrap>", line 983, in _find_and_load
2021-12-14T05:14:28.142249471Z File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
2021-12-14T05:14:28.142254171Z File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
2021-12-14T05:14:28.142258771Z File "<frozen importlib._bootstrap_external>", line 728, in exec_module
2021-12-14T05:14:28.142263371Z File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
2021-12-14T05:14:28.142268172Z File "/opt/python/3.7.9/lib/python3.7/site-packages/gunicorn/workers/geventlet.py", line 20, in <module>
2021-12-14T05:14:28.142272972Z from eventlet.wsgi import ALREADY_HANDLED as EVENTLET_ALREADY_HANDLED
2021-12-14T05:14:28.142277472Z ImportError: cannot import name 'ALREADY_HANDLED' from 'eventlet.wsgi' (/tmp/8d9bebfefe8421c/antenv/lib/python3.7/site-packages/eventlet/wsgi.py)
2021-12-14T05:14:28.142282173Z ]
以上两个问题都是通过修改 requirements.txt 中 eventlet==0.30.2 后，重新部署。问题解决。
参考资料
App Service for Linux 中实现 WebSocket 功能 (Python SocketIO) : https://www.cnblogs.com/lulight/p/15501015.html
当在复杂的环境中面临问题，格物之道需：浊而静之徐清，安以动之徐生。 云中，恰是如此!
分类: 【Azure 应用服务】
标签: App Service, Azure Developer, Python flask, Python Websocket HTTP/HTTPS
