与Flask应用程序一起运行代码 [英] Run code alongside a Flask application

问题描述

我已经为我的python应用程序编写了一个Web界面.在运行 export FLASK_APP = main.py 然后运行 flask run 时，此功能可以很好地运行.现在，我希望实际的应用程序也能运行，因此该界面可能会很有用.

I've written a web interface for my python application. This functions beautifully when running export FLASK_APP=main.py followed by flask run. Now I want the actual application to also run, so the interface can be useful.

下面的代码是我的main.py，在这里我将烧瓶应用程序称为工厂函数.

The code below is my main.py, where I call the flask applications factory function.

from webinterface import create_app

if __name__ == '__main__':
    create_app()
    while(True):
        # Some code logging different things

我想在无限循环内做一些事情，但是，当我尝试运行该应用程序时，它要么只运行Web界面，要么运行无限循环，具体取决于我是否使用 flask run 或 python main.py .

I want to do stuff inside the infinite loop, however when I try to run the application, it either runs only the web interface or the infinte loop, depending if I start it using flask run or python main.py.

我如何最好地做到这一点?

How do I best accomplish this?

推荐答案

在前台应用程序的线程中运行Flask是可能的，并且有时很方便.有一个窍门，一个大陷阱和一个约束.

It's possible, and sometime convenient, to run Flask in a thread off of a foreground application. There is a trick, a big pitfall, and a constraint.

约束是，这是您要在安全"环境中执行的操作(例如，在便携式计算机上以本地浏览器为服务器，或在家庭Intranet上)，因为这涉及到运行开发服务器，即您不想在敌对环境中做的事情.您也不能使用自动页面重新加载(但可以启用调试).

The constraint is that this is something you'll want to do in a "safe" environment (e.g. on your laptop to server a local browser, or on your home intranet), as it involves running the development server, which is something you don't want to be doing in a hostile environment. You also can't use automatic page reloading (but you can enable debug).

陷阱是，如果UI与前景应用程序共享任何不平凡的状态(包括字典)，则需要使用共享的 threading.Lock()来保护此类访问一次只有一个线程正在读取或写入数据.

The pitfall is that if the UI is sharing any non-trivial state (including dicts) with the foreground app, you'll need to use a shared threading.Lock() to guard access such that only one thread at a time is reading or writing data.

诀窍是在创建共享状态之后但在启动之前，将对共享状态的引用注入到应用程序的配置中，例如:

The trick is to inject a reference to shared state into the app's config after you create it but before you start it, doing something like:

def webserver(state):
    app.config['STATE'] = state
    # If running on, say, a Raspberry Pi, use 0.0.0.0 so that
    # you can connect to the web server from your intranet.
    app.run(host='0.0.0.0', use_reloader=False, debug=True)

def main():
    state = SharedState()
    web_thread = threading.Thread(target=webserver, args=(state,))
    web_thread.start()

    state.set('counter' 0)
    while True:
        # Do whatever you want in the foreground thread
        state.set('counter', state.get('counter') + 1)

class SharedState():
    def __init__(self):
        self.lock = threading.Lock()
        self.state = dict()

    def get(self, key):
        with self.lock:
            return self.state.get(key)

    def set(self, key, value):
        with self.lock:
            self.state[key] = value

然后，在Flask视图功能中执行类似的操作

Then, from within Flask view functions, do something like

@app.route('/')
def home():
    state = app.config['STATE']
    counter = state.get(counter)
    return render_template("index.html", counter=counter)

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