Flask应用程序在开发服务器上工作，但在使用mod_wsgi部署在httpd上时遇到问题 [英] Flask app working on dev server but facing issues when deployed on httpd with mod_wsgi

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本文介绍了Flask应用程序在开发服务器上工作，但在使用mod_wsgi部署在httpd上时遇到问题的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我在参加的一次Python培训中得到了一项任务。我使用Flask1.0/python3.6为我的一个项目构建了一个简单的应用程序。我的应用程序需要实现以下功能：

  1. 从学院内部应用调用接口
  2. 在Oracle数据库上运行数据库查询并在网页上显示数据。

我在后端(Python)编写了一组函数来实现这一点，并使用Ajax来调用这些函数。flask dev服务器上一切运行正常。现在我需要将其移动到生产服务器，我使用mod_wsgi和httpd来实现这一点。经过一番努力，我让我的应用程序在生产服务器上运行，但是在运行这两个函数时，我的python代码失败，出现500个错误。

jquery.min.js:4 POST http://server.com/flaskprod/requestbots 500 (INTERNAL SERVER ERROR)

POST http://server.com/flaskprod/home 500 (INTERNAL SERVER ERROR)

我检查了Apache httpd error_log，看到以下错误。

调用接口错误：

  [Mon Jul 02 13:48:41.302510 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]   File "/var/www/flask-prod/flaskprod.py", line 230, in createCM
[Mon Jul 02 13:48:41.302513 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]     r = requests.post(URL, auth=creds, data=json.dumps(DATAS), proxies=proxies, headers=headers)
[Mon Jul 02 13:48:41.302515 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]   File "/usr/local/lib/python3.6/site-packages/requests/api.py", line 112, in post
[Mon Jul 02 13:48:41.302517 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]     return request('post', url, data=data, json=json, **kwargs)
[Mon Jul 02 13:48:41.302519 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]   File "/usr/local/lib/python3.6/site-packages/requests/api.py", line 58, in request
[Mon Jul 02 13:48:41.302522 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]     return session.request(method=method, url=url, **kwargs)
[Mon Jul 02 13:48:41.302524 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]   File "/usr/local/lib/python3.6/site-packages/requests/sessions.py", line 508, in request
[Mon Jul 02 13:48:41.302526 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]     resp = self.send(prep, **send_kwargs)
[Mon Jul 02 13:48:41.302528 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]   File "/usr/local/lib/python3.6/site-packages/requests/sessions.py", line 618, in send
[Mon Jul 02 13:48:41.302530 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]     r = adapter.send(request, **kwargs)
[Mon Jul 02 13:48:41.302532 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]   File "/usr/local/lib/python3.6/site-packages/requests/adapters.py", line 502, in send
[Mon Jul 02 13:48:41.302539 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212]     raise ProxyError(e, request=request)
[Mon Jul 02 13:48:41.302546 2018] [wsgi:error] [pid 18202] [remote 1.1.1.1:1212] requests.exceptions.ProxyError: HTTPSConnectionPool(host='exampleee.com', port=443): Max retries exceeded with url: /api/now/change/change_req (Caused by ProxyError('Cannot connect to proxy.', NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fac76d37eb8>: Failed to establish a new connection: [Errno 13] Permission denied',)))

查询数据库时出错：

    [Mon Jul 02 13:51:23.148685 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]   File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 2292, in wsgi_app
[Mon Jul 02 13:51:23.148687 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]     response = self.full_dispatch_request()
[Mon Jul 02 13:51:23.148690 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]   File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1815, in full_dispatch_request
[Mon Jul 02 13:51:23.148693 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]     rv = self.handle_user_exception(e)
[Mon Jul 02 13:51:23.148695 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]   File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1718, in handle_user_exception
[Mon Jul 02 13:51:23.148698 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]     reraise(exc_type, exc_value, tb)
[Mon Jul 02 13:51:23.148700 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]   File "/usr/local/lib/python3.6/site-packages/flask/_compat.py", line 35, in reraise
[Mon Jul 02 13:51:23.148702 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]     raise value
[Mon Jul 02 13:51:23.148705 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]   File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1813, in full_dispatch_request
[Mon Jul 02 13:51:23.148707 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]     rv = self.dispatch_request()
[Mon Jul 02 13:51:23.148709 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]   File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1799, in dispatch_request
[Mon Jul 02 13:51:23.148711 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]     return self.view_functions[rule.endpoint](**req.view_args)
[Mon Jul 02 13:51:23.148714 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]   File "/var/www/flask-prod/flaskprod.py", line 97, in get_cms_requested_for_approval
[Mon Jul 02 13:51:23.148716 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]     CMREQ = connect_bcc(queryCMREQ)
[Mon Jul 02 13:51:23.148718 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]   File "/var/www/flask-prod/flaskprod.py", line 86, in connect_bcc
[Mon Jul 02 13:51:23.148721 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]     connection = cx_Oracle.connect(bccConnectionString)
[Mon Jul 02 13:51:23.148725 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212] cx_Oracle.DatabaseError: DPI-1047: 64-bit Oracle Client library cannot be loaded: "libclntsh.so: cannot open shared object file: No such file or directory". See https://oracle.github.io/odpi/doc/installation.html#linux for help
[Mon Jul 02 13:51:23.148750 2018] [wsgi:error] [pid 18200] [remote 1.1.1.1: 1212]
附注：flask dev服务器中一切运行正常。那里没有问题。我将在下面添加更多信息。

这是我的配置文件：

WSGIPassAuthorization On

WSGIScriptAlias /flaskprod /var/www/flask-prod/flaskprod.wsgi

WSGIDaemonProcess flaskprod user=cld group=users processes=5 threads=5 maximum-requests=1000 umask=0007
WSGIProcessGroup flaskprod
WSGISocketPrefix /var/run/wsgi

<Directory /var/www/flask-prod/>
Order allow,deny
Allow from all
</Directory>

我的python代码片段：

def connect_bcc(query):
    connectionString = 'bla bla'
    connection = cx_Oracle.connect(connectionString)
    cursor = connection.cursor()
    cursor.execute(query)
    return cursor.fetchall()
    cursor.close()
    connection.close()

 @app.route('/requestbots', methods=['GET','POST'])
 def get_cms_requested_for_approval():
    if request.method == "POST":
        queryCMREQFORAPPRVL = "SELECT * FROM....."
        CMREQ = connect_bcc(queryCMREQ)

        print (CM)
        return json.dumps({'CM': CM})

js代码片段：

function getResult() {
        $.ajax({
                type: "POST",
                url: $SCRIPT_ROOT + "/requestbots".....bla bla
         })
}

推荐答案

所以，我想出来了。互联网太棒了！我花了一段时间寻找此问题的答案，因此在下面提及所有详细信息。

这两个问题都与SELinux有关。如果您想知道那是什么-安全增强的Linux是一个Linux内核安全模块，它提供了一种支持访问控制安全策略的机制。

如果遇到类似问题，请检查与您的Web服务器相关的各种布尔值的SELinux布尔值：

getsebool -a | grep httpd

对我而言，以下两个参数处于关闭状态。

httpd_can_network_connect --> off
httpd_can_network_connect_db --> off

我使用下面的命令打开了它们。

setsebool httpd_can_network_connect on -P

setsebool httpd_can_network_connect_db on -P

 (-P is used to make the change persisting)

就是这样。现在，一切都运行得如鱼得水。

这篇关于Flask应用程序在开发服务器上工作，但在使用mod_wsgi部署在httpd上时遇到问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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