使用Python自动生成Docker Nginx反向代理配置

由于在测试环境上用docker部署了多个应用，而且他们的端口有的相同，有的又不相同，数量也比较多，在使用jenkins发版本的时候，不好配置，于是想要写一个脚本，能在docker 容器创建、停止的时候，自动生成nginx反向代理，然后reload nginx

我的原则是尽量简单，轻量，内存占用少

目标很明确，只要能监听到docker的容器启动/停止事件，即可

网上查了一下可以用docker events来监听docker事件，试了一下，发现基本可以满足，于是用Python写了一段程序，用来监听docker事件

python
#!/usr/bin/python
# coding: utf8
import os
import json
import re
import subprocess

def override(path, text):
    if not os.path.exists(path) and os.path.exists(path+"_temp"):
        os.rename(path+"_temp",path)
    fw = open(path+"_temp", 'wb')
    fw.write(text)
    fw.close()
    if os.path.exists(path):
        os.remove(path)
    os.rename(path+"_temp", path)

def read(path):
    try:
        fr = open(path, "rb")
    except IOError:
        print "The file don't exist, Please double check!"
        return
    lines = fr.readlines()
    ret = ''
    for line in lines:
        ret += line
    return ret

def read_jsonfile(path):
    return json.loads(read(path))

def cmd(command):
    return os.popen(command).read()

def get_name(container):
    return cmd("docker inspect -f '{{.Name}}' " + container).replace("/", "").replace('\n', '')

def get_ip(container):
    return cmd("docker inspect -f '{{.NetworkSettings.IPAddress}}' " + container).replace('\n', '')

def get_port(container):
    return cmd("docker inspect -f '{{.Config.ExposedPorts}}' " + container).replace('/tcp:{}]', '').replace('map[', '').replace('\n', '')

def get_info(container):
    filename = "/var/lib/docker/containers/" + container + "/config.v2.json"
    config = read_jsonfile(filename)

name = config['Name'].replace("/", "")
    port = config['Config']['ExposedPorts'].keys()[0].replace('/tcp', '')
    ip = cmd("docker inspect -f '{{.NetworkSettings.IPAddress}}' " + name)
    # ip = config['NetworkSettings']['Networks']['bridge']['IPAddress']

ret = {'name': name, 'port': port, 'ip': ip}
    return ret

tpl = """
    server {
        listen 80;
        server_name $name.test.com;
        location / {
        proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header Host $http_host;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_pass $ip:$port;
        }
    }
"""

def generate_conf():
    print "generate_conf"
    out = cmd("docker ps | grep -v CONTAINER | awk '{print $1}'")
    containers = out.split("\n")
    servers = ''
    hosts = ''
    for con in containers:
        if con != '':
            name = get_name(con)
            ip = get_ip(con)
            port = get_port(con)
            print ip, port
            if len(port) >= 2:
                servers += tpl.replace("$name", name).replace("$ip", ip).replace("$port", port)
                hosts += "11.12.13.14 " + name + ".test.com\n"
    override('/usr/local/openresty/nginx/conf/vhost.conf', servers)
    override('/usr/local/openresty/nginx/html/vhost.html', "<pre>" + hosts + "</pre>")

def reload_nginx():
    print "reload nginx"
    cmd('nginx -s reload')

def auto_reload():
    generate_conf()
    reload_nginx()

print " ==================== docker events ==================== "

# auto_reload()

proc = subprocess.Popen(["docker", "events"],
                        # shell=True,  # windows: true, linux: false
                        stdout=subprocess.PIPE)