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211 lines
6.2 KiB
Markdown
211 lines
6.2 KiB
Markdown
## 使用
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### 术语
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首先介绍几个术语。
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* 服务 (service)：一个应用容器，实际上可以运行多个相同镜像的实例。
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* 项目 (project)：由一组关联的应用容器组成的一个完整业务单元。
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可见，一个项目可以由多个服务（容器）关联而成，Compose 面向项目进行管理。
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### 场景
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下面，我们创建一个经典的 Web 项目：一个 [Haproxy](http://www.haproxy.org/)，挂载三个 Web 容器。
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创建一个 `compose-haproxy-web` 目录，作为项目工作目录，并在其中分别创建两个子目录：`haproxy` 和 `web`。
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### web 子目录
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这里用 Python 程序来提供一个简单的 HTTP 服务，打印出访问者的 IP 和 实际的本地 IP。
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#### index.py
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编写一个 `index.py` 作为服务器文件，代码为
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```python
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#!/usr/bin/python
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#authors: yeasy.github.com
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#date: 2013-07-05
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import sys
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import BaseHTTPServer
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from SimpleHTTPServer import SimpleHTTPRequestHandler
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import socket
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import fcntl
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import struct
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import pickle
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from datetime import datetime
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from collections import OrderedDict
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class HandlerClass(SimpleHTTPRequestHandler):
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def get_ip_address(self,ifname):
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s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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return socket.inet_ntoa(fcntl.ioctl(
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s.fileno(),
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0x8915, # SIOCGIFADDR
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struct.pack('256s', ifname[:15])
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)[20:24])
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def log_message(self, format, *args):
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if len(args) < 3 or "200" not in args[1]:
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return
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try:
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request = pickle.load(open("pickle_data.txt","r"))
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except:
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request=OrderedDict()
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time_now = datetime.now()
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ts = time_now.strftime('%Y-%m-%d %H:%M:%S')
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server = self.get_ip_address('eth0')
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host=self.address_string()
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addr_pair = (host,server)
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if addr_pair not in request:
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request[addr_pair]=[1,ts]
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else:
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num = request[addr_pair][0]+1
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del request[addr_pair]
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request[addr_pair]=[num,ts]
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file=open("index.html", "w")
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file.write("<!DOCTYPE html> <html> <body><center><h1><font color=\"blue\" face=\"Georgia, Arial\" size=8><em>HA</em></font> Webpage Visit Results</h1></center>")
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for pair in request:
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if pair[0] == host:
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guest = "LOCAL: "+pair[0]
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else:
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guest = pair[0]
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if (time_now-datetime.strptime(request[pair][1],'%Y-%m-%d %H:%M:%S')).seconds < 3:
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file.write("<p style=\"font-size:150%\" >#"+ str(request[pair][1]) +": <font color=\"red\">"+str(request[pair][0])+ "</font> requests " + "from <<font color=\"blue\">"+guest+"</font>> to WebServer <<font color=\"blue\">"+pair[1]+"</font>></p>")
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else:
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file.write("<p style=\"font-size:150%\" >#"+ str(request[pair][1]) +": <font color=\"maroon\">"+str(request[pair][0])+ "</font> requests " + "from <<font color=\"navy\">"+guest+"</font>> to WebServer <<font color=\"navy\">"+pair[1]+"</font>></p>")
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file.write("</body> </html>")
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file.close()
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pickle.dump(request,open("pickle_data.txt","w"))
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if __name__ == '__main__':
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try:
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ServerClass = BaseHTTPServer.HTTPServer
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Protocol = "HTTP/1.0"
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addr = len(sys.argv) < 2 and "0.0.0.0" or sys.argv[1]
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port = len(sys.argv) < 3 and 80 or int(sys.argv[2])
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HandlerClass.protocol_version = Protocol
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httpd = ServerClass((addr, port), HandlerClass)
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sa = httpd.socket.getsockname()
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print "Serving HTTP on", sa[0], "port", sa[1], "..."
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httpd.serve_forever()
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except:
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exit()
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```
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#### index.html
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生成一个临时的 `index.html` 文件，其内容会被 index.py 更新。
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```bash
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$ touch index.html
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```
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#### Dockerfile
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编写 `Dockerfile` 文件，内容为
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```docker
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FROM python:2.7
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WORKDIR /code
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ADD . /code
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EXPOSE 80
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CMD python index.py
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```
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### haproxy 目录
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编写 `haproxy.cfg` 文件，内容为
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```bash
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global
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log 127.0.0.1 local0
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log 127.0.0.1 local1 notice
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defaults
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log global
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mode http
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option httplog
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option dontlognull
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timeout connect 5000ms
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timeout client 50000ms
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timeout server 50000ms
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listen stats
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bind 0.0.0.0:70
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stats enable
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stats uri /
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frontend balancer
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bind 0.0.0.0:80
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mode http
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default_backend web_backends
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backend web_backends
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mode http
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option forwardfor
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balance roundrobin
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server weba weba:80 check
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server webb webb:80 check
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server webc webc:80 check
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option httpchk GET /
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http-check expect status 200
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```
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### docker-compose.yml
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编写 docker-compose.yml 文件，这个是 Compose 使用的主模板文件。内容十分简单，指定 3 个 web 容器，以及 1 个 haproxy 容器。
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```yaml
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version: "3"
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services:
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weba:
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build: ./web
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expose:
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- 80
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webb:
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build: ./web
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expose:
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- 80
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webc:
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build: ./web
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expose:
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- 80
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haproxy:
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image: haproxy:latest
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volumes:
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- ./haproxy:/haproxy-override
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- ./haproxy/haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg:ro
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links:
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- weba
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- webb
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- webc
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ports:
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- "80:80"
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- "70:70"
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expose:
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- "80"
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- "70"
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```
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### 运行 compose 项目
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现在 compose-haproxy-web 目录结构如下：
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```bash
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compose-haproxy-web
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├── docker-compose.yml
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├── haproxy
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│ └── haproxy.cfg
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└── web
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├── Dockerfile
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├── index.html
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└── index.py
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```
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在该目录下执行 `docker-compose up` 命令，会整合输出所有容器的输出。
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```bash
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$ docker-compose up
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Recreating composehaproxyweb_webb_1...
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Recreating composehaproxyweb_webc_1...
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Recreating composehaproxyweb_weba_1...
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Recreating composehaproxyweb_haproxy_1...
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Attaching to composehaproxyweb_webb_1, composehaproxyweb_webc_1, composehaproxyweb_weba_1, composehaproxyweb_haproxy_1
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```
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此时访问本地的 80 端口，会经过 haproxy 自动转发到后端的某个 web 容器上，刷新页面，可以观察到访问的容器地址的变化。
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访问本地 70 端口，可以查看到 haproxy 的统计信息。
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当然，还可以使用 consul、etcd 等实现服务发现，这样就可以避免手动指定后端的 web 容器了，更为灵活。
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