Detailed introduction to deployment in Python

I have been learning flask for a while, but I have never deployed it, so I was thinking about how to deploy it. Think about it, let’s get the service started first, so I thought about getting the service started first. Here is the choice It is Flask+uwsgi+Nginx+Ubuntu. The Python option is 2.7.2. This is the one that comes with the Ubuntu system. It feels simple to learn without having to go through the software connection. Currently, my own flask is written in python3, and I will slowly transition to it. , let’s get this figured out first, then it will be very easy to optimize. In fact, I don't know much about many principles. Let's set this up first and slowly understand the logic inside.

Nginx

Nginx is an efficient web server and reverse proxy server that can be used as a load balancing (when n users access the server, it can achieve offloading and share the server's load. pressure), compared with Apache, Nginx supports high concurrency, can support millions of TCP connections, and hundreds of thousands of concurrent connections. It is simple to deploy, consumes less memory, and has low cost. However, Nginx does not have as many modules as Apache. Nginx supports uWSGI's uwsgi protocol, so we can combine Nginx with uWSGI, and Nginx hands over dynamic content to uWSGI for processing through uwsgi_pass.

Official documentation is here

The best Nginx tutorial is here

uwsgi

uWSGI is a web server that implements WSGI protocol, uwsgi, http and other protocols. The function of HttpUwsgiModule in Nginx is to exchange with uWSGI server.

Pay attention to the distinction between the three concepts of WSGI / uwsgi / uWSGI.

• Those who have read the previous section will know that WSGI is a communication protocol.
• uwsgi is a line protocol rather than a communication protocol. It is often used for data communication between the uWSGI server and other network servers.
• uWSGI is a web server that implements two protocols, uwsgi and WSGI.

uwsgi protocol is a uWSGI server's own protocol. It is used to define the type of information to be transmitted. The first 4 bytes of each uwsgi packet is a description of the type of information to be transmitted. It Compared with WSGI, they are two different things.

Preparation, first, let’s install the packages we need. First of all, this is my newly installed system, so there is no pip, so I will install pip first

sudo apt-get install python-pip

Use the following command to install flask

pip install flask

After installation, we can test it,

import flask

No error is reported, which proves that our flask is installed successfully. So the next thing we have to do is install ngnix and uwsgi.

sudo apt-get install nginx

After installation, we can start it first, nginx start directly starts from the command line, simple and crude

This way we nginx has started successfully. Next, we use pip to install uwsgi

After we install it, let’s start working.

First I create an app under hellowflak Python package,

#app/__init__.pyfrom flask import Flask
app = Flask(__name__)from app import view

Next we create view.py

from app import app
@app.route('/')def index():return 'hellow'

Then we create hello in the same directory as app. py

from app import appif __name__ == "__main__":
    app.run()

, then we can use Python to debug our program locally,

then we can use the browser to Take a look, enter the address and you can get this. From this point of view, there is no problem with our flask program.

Then what we have to do next is to let nginx take on the web service.

What I did here was to delete the nginx configuration file simply and rudely

$ sudo rm /etc/nginx/sites-enabled/default

Next, I created a configuration file under hellowflask

server {
    listen      8081;
    server_name 127.0.0.1;
    charset     utf-8;
    client_max_body_size 75M;

    location / { try_files $uri @app; }
    location @app {
        include uwsgi_params;
        uwsgi_pass 127.0.0.1:9000;
    }
}

A brief explanation: server_name can be a domain name or an IP address. uwsgi_pass indicates the communication method between Nginx and uwsgi. What I chose here is the specified port number.

Then let’s soft-connect our configuration to nginx.

sudo ln -s <span class="hljs-regexp"><span class="hljs-regexp">/home/liwanlei/Desktop/hellowflask/<span class="hljs-regexp">helloflask_nginx.conf /etc<span class="hljs-regexp">/nginx/conf.d/<br/>这样我们再去启动我们的nginx，</span></span></span></span>

sudo /etc/init.d/nginx restart

What’s here is not a welcome, but a 502 error, because our current uwsgi file has not been configured yet, and we have not started uwsgi, so the next step is to get it out For this uwsgi, the example below is my configuration.

[uwsgi]    
    base = /home/liwanlei/Desktop/hellowflask
    app = hello#module = %(app)pidfile = /var/run/uwsgi.pid
    master = true
    wsgi-file = /home/liwanlei/Desktop/hellowflask/hello.py
    pythonpath = /usr/bin/python
    chdir = /home/liwanlei/Desktop/hellowflask
    socket = 127.0.0.1:9000callable = app
    logto = %n.log
    plugins = python
    processes = 8master = true

At this time our uwsgi has been configured, so let’s start it,

sudo /usr/bin/uwsgi --ini/home/liwanlei/Desktop/hellowflask/helloflask_uwsgi.ini

我们去重新启动我们的nginx，

sudo nginx <span class="hljs-_">reload<br/>平滑重启可以用用，重新加载配置文件，用新的工作进程代替旧的工作进程。<br/></span>

sudo nginx -s reload

<span class="hljs-_"><br/>启动后，我这里修改了地址，这里就可以直接访问了，那么我们的部署这样就算可以了，简单的。<br/><img src="/static/imghwm/default1.png"  data-src="https://img.php.cn/upload/article/000/000/001/25f4d9be3a729ae5fc17c2fefb915c9c-3.jpg?x-oss-process=image/resize,p_40"  class="lazy" alt=""/></span>

 <br>

完工之后，感觉还是很简单的 有问题那么就去看log，只要log配置得当，那么排除错误是很快的。

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