問題描述

在成功的部署Python flask應(yīng)用到App Service (Windows)后漆撞，如果需要把當(dāng)前項(xiàng)目（如：hiflask）作為一個(gè)子項(xiàng)目(子站點(diǎn)），把web.config文件從wwwroot中移動(dòng)到項(xiàng)目文件夾中挚歧。訪問時(shí)扛稽，確遇見了404 Not Found的錯(cuò)誤。

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查看flask項(xiàng)目的啟動(dòng)日志滑负，可以看見項(xiàng)目啟動(dòng)已經(jīng)成功庇绽。但是為什么請(qǐng)求一直都是404的問題呢？

2021-09-10 05:29:58.224796: wfastcgi.py will restart when files in D:\home\site\wwwroot\hiflask\ are changed: .*((\.py)|(\.config))$
2021-09-10 05:29:58.240445: wfastcgi.py 3.0.0 initialized

問題解決

在搜索 flask return 404問題后橙困，發(fā)現(xiàn)是因?yàn)?URL前綴（prefixed ）的問題。因?yàn)楫?dāng)前的flask應(yīng)用訪問路徑不再是根目錄（/）耕餐，而是(/hiflask)凡傅。 所以需要 flask項(xiàng)目中使用 中間件 來(lái)處理 url前綴的問題。

原文內(nèi)容為：https://stackoverflow.com/questions/18967441/add-a-prefix-to-all-flask-routes/36033627#36033627

You have to do is to write a middleware to make the following changes:

1. modify PATH_INFO to handle the prefixed url.
2. modify SCRIPT_NAME to generate the prefixed url.

Like this:

class PrefixMiddleware(object):

    def __init__(self, app, prefix=''):
        self.app = app
        self.prefix = prefix

    def __call__(self, environ, start_response):

        if environ['PATH_INFO'].startswith(self.prefix):
            environ['PATH_INFO'] = environ['PATH_INFO'][len(self.prefix):]
            environ['SCRIPT_NAME'] = self.prefix
            return self.app(environ, start_response)
        else:
            start_response('404', [('Content-Type', 'text/plain')])
            return ["This url does not belong to the app.".encode()]

Wrap your app with the middleware, like this:

from flask import Flask, url_for

app = Flask(__name__)
app.debug = True
app.wsgi_app = PrefixMiddleware(app.wsgi_app, prefix='/foo')

@app.route('/bar')
def bar():
    return "The URL for this page is {}".format(url_for('bar'))

if __name__ == '__main__':
    app.run('0.0.0.0', 9010)

Visit http://localhost:9010/foo/bar,

You will get the right result: The URL for this page is /foo/bar

而在App Service中的解決方式就是添加了 PrefixMiddleware肠缔，并指定prefix為 /hiflask 夏跷。 附上完成的hiflask/app.py 代碼和web.config內(nèi)容。

hiflask/app.py

from flask import Flask
from datetime import datetime
from flask import render_template

import re

class PrefixMiddleware(object):
    def __init__(self, app, prefix=''):
        self.app = app
        self.prefix = prefix

    def __call__(self, environ, start_response):
        if environ['PATH_INFO'].startswith(self.prefix):
            environ['PATH_INFO'] = environ['PATH_INFO'][len(self.prefix):]
            environ['SCRIPT_NAME'] = self.prefix
            return self.app(environ, start_response)
        else:
            start_response('404', [('Content-Type', 'text/plain')])
            return ["This url does not belong to the app.".encode()]

#if __name__ =="__name__"
app = Flask(__name__)
app.debug = True
app.wsgi_app = PrefixMiddleware(app.wsgi_app, prefix='/hiflask')
# @app.route("/")
# def home():
#     return "Hello, Flask!"

print("flask applicaiton started and running..." +datetime.now().strftime("%m/%d/%Y, %H:%M:%S"))

# Replace the existing home function with the one below
@app.route("/")
def home():
    return render_template("home.html")

# New functions
@app.route("/about/")
def about():
    return render_template("about.html")

@app.route("/contact/")
def contact():
    return render_template("contact.html")

@app.route("/hello/")
@app.route("/hello/<name>")
def hello_there(name = None):
    return render_template(
        "hello_there.html",
        name=name,
        date=datetime.now()
    )

@app.route("/api/data")
def get_data():
    return app.send_static_file("data.json")

if __name__ == '__main__':
    app.run(debug=True)

hiflask/web.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <appSettings>
    <add key="WSGI_HANDLER" value="app.app"/>
    <add key="PYTHONPATH" value="D:\home\site\wwwroot\hiflask"/>
    <add key="WSGI_LOG" value="D:\home\site\wwwroot\hiflask\hiflasklogs.log"/>
  </appSettings>
  <system.webServer>
    <handlers>
    <add name="PythonHandler" path="*" verb="*" modules="FastCgiModule" scriptProcessor="D:\home\python364x64\python.exe|D:\home\python364x64\wfastcgi.py" resourceType="Unspecified" requireAccess="Script"/>
    </handlers>
  </system.webServer>
</configuration>

最終效果(作為子項(xiàng)目部署完成成功明未，所以一個(gè)app service就可以部署多個(gè)站點(diǎn))

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提醒一點(diǎn)：App Service中如果要部署多站點(diǎn)槽华，需要在Configration 中配置 Virtual Applications。

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參考資料：

https://stackoverflow.com/questions/18967441/add-a-prefix-to-all-flask-routes/36033627#36033627

https://www.cnblogs.com/lulight/p/15220297.html

https://www.cnblogs.com/lulight/p/15227028.html

當(dāng)在復(fù)雜的環(huán)境中面臨問題趟妥，格物之道需：濁而靜之徐清猫态，安以動(dòng)之徐生。 云中披摄，恰是如此!

分類: 【Azure 應(yīng)用服務(wù)】

標(biāo)簽: flask項(xiàng)目作為子應(yīng)用的404問題, 使用Flask框架部署Python應(yīng)用, Python web.config, App Service, Python Flask 404 Not Found