选用 CentOS 7.5 版本部署 Flask 站点，需要安装的 Software Packages 有:

• nginx
• gunicorn
• supervisor
• flask

Nginx

Nginx是一个异步框架的Web服务器，也可以用作反向代理，负载均衡器和 HTTP 缓存。该软件由 Igor Sysoev 创建，并于2004年首次公开发布。

安装

# yum -y install epel-release
# yum -y install nginx

启动

# systemctl enable nginx
# systemctl start nginx
# systemctl status nginx

操作
在修改 nginx.conf 配置后，先测试修改后的配置文件是否正确。

# nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

如果返回 ok, 再执行 nginx -s reload 重新加载配置文件。
默认的配置文件位于 /etc/nginx/nginx.conf, 也可以设置配置文件: nginx -c filename。

Gunicorn

Green Unicorn 是用于 UNIX 的 Python WSGI HTTP，是 pre-fork 多进程工作模型。

安装

# yum -y install python-pip
# pip install gunicorn
# pip install gevent

示例

# cat test.py
def app(environ, start_response):
    """Simplest possible application object"""
    data = b'Hello Dragon!\n'
    status = '200 OK'
    response_headers = [
        ('Content-type', 'text/plain'),
        ('Content-Length', str(len(data)))
    ]
    start_response(status, response_headers)
    return iter([data])
# gunicorn --workers=2 test:app

Supervisor

Supervisor 是一个使用 Python 写的 C/S 架构的进程管理工具，它可以很方便的启动、停止、重启一个或多个进程。如果 Supervisor 管理的进程意外被杀死，它会将该进程重新拉起。

安装

# pip install supervisor
# yum -y install supervisor

启动

# systemctl enable supervisord
# systemctl start supervisord

Flask

Flask 是一个使用 Python 编写的轻量级 Web应用框架。基于 Werkzeug WSGI 工具箱和 Jinja2 模板引擎。

安装

# pip install Flask

Example

项目部署目录结构:

# mkdir -p /feiran/{etc,lib,log,run}
# tree /feiran
/feiran
├── etc
├── lib
├── log
└── run

项目命名为 dragon

# cat /feiran/lib/dragon/dragon.py
from flask import Flask
app = Flask("Dragon")

@app.route("/")
def dragon():
    return "Hi, Dragon!"

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

使用 Supervisor 管理 Gunicorn 进程

# cat /etc/supervisord.d/dragon.ini
[program:dragon]
environment=PYTHONPATH='/feiran/lib/dragon'
stdout_logfile=/feiran/log/dragon_gunicorn.log
autostart=true
autorestart=unexpected
redirect_stderr=true
stopsignal=QUIT
command=gunicorn -c /feiran/etc/dragon_gunicorn.py dragon:app

Gunicorn 的配置文件, Async Workers:gevent

# cat /feiran/etc/dragon_gunicorn.py
import multiprocessing

workers = multiprocessing.cpu_count() * 2 + 1
worker_class = "gunicorn.workers.ggevent.GeventWorker"
worker_connections = 4096

# Wait keepalive connection for 30 seconds
keepalive = 30
timeout = 600
graceful_timeout = 12000
loglevel = "error"
access_logfile = "/feiran/log/dragon_gunicorn.log"
bind = ["unix:/feiran/run/dragon_gunicorn.sock", "0.0.0.0:8080"]
pidfile = "/feiran/run/dragon_gunicorn.pid"

执行 systemctl restart supervisord
执行 supervisorctl start dragon 启动 dragon 服务
执行 supervisorctl status dragon 查看 dragon 状态

最后一步,使用 Nginx 作为反向代理

# cat /etc/nginx/nginx.conf
# For more information on configuration, see:
#   * Official English Documentation: http://nginx.org/en/docs/
#   * Official Russian Documentation: http://nginx.org/ru/docs/

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;

events {
    worker_connections 1024;
}

http {
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile            on;
    tcp_nopush          on;
    tcp_nodelay         on;
    keepalive_timeout   65;
    types_hash_max_size 2048;

    include             /etc/nginx/mime.types;
    default_type        application/octet-stream;

    upstream gunicorn {
        server unix:/feiran/run/dragon_gunicorn.sock fail_timeout=5;
    }

    server {
        listen       80 default_server;
        listen       [::]:80 default_server;
        server_name  _;
        root         /usr/share/nginx/html;

        location / {
            set $upstream 'gunicorn';

            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;

            proxy_pass http://$upstream;
        }

        error_page 404 /404.html;
            location = /40x.html {
        }

        error_page 500 502 503 504 /50x.html;
            location = /50x.html {
        }
    }
}

修改 nginx.conf 修改后，记得执行 nginx -t 和 nginx -s reload

测试 Flask 站点

dragon.png

Flask 站点上线后的目录结构

# tree /feiran/
/feiran/
├── etc
│   └── dragon_gunicorn.py
├── lib
│   └── dragon
│       ├── dragon.py
│       └── dragon.pyc
├── log
│   └── dragon_gunicorn.log
└── run
    ├── dragon_gunicorn.pid
    └── dragon_gunicorn.sock

5 directories, 6 files

参考资料

http://nginx.org/en/docs/
https://gunicorn.org/
http://docs.gunicorn.org/en/stable/
http://supervisord.org/
http://flask.pocoo.org/