摘要：在使用的過程中，一般我們常用的方式是手工填寫主機列表或者是角色列表，但是這樣當服務器數量超級多的時候，你會有想死的感覺的。

在使用 Fabric 的過程中，一般我們常用的方式是手工填寫主機列表或者是角色列表，但是這樣當服務器數量超級多的時候，你會有想死的感覺的。正好公司有 cmdb 的話，就可以結合 CMDB 來做。

  
PS：如果公司沒有開發 CMDB 系統，也自己盡量弄個簡單的系統錄入服務器數據吧，不要那么復雜，提供 API，能獲取主機列表即可。

通過參考 Fabric 的官方文檔的 Using execute with dynamically-set host lists，其中有這么一段示例代碼：

from fabric.api import run, execute, task

# For example, code talking to an HTTP API, or a database, or ...
from mylib import external_datastore

# This is the actual algorithm involved. It does not care about host
# lists at all.
def do_work():
    run("something interesting on a host")

# This is the user-facing task invoked on the command line.
@task
def deploy(lookup_param):
    # This is the magic you don"t get with @hosts or @roles.
    # Even lazy-loading roles require you to declare available roles
    # beforehand. Here, the sky is the limit.
    host_list = external_datastore.query(lookup_param)
    # Put this dynamically generated host list together with the work to be
    # done.
    execute(do_work, hosts=host_list)

然后執行命令：

$ fab deploy:app
$ fab deploy:db

其生成主機列表的格式如下：

["10.2.5.1", "10.2.5.2", "10.2.5.3", "10.2.5.4", "10.2.5.5", "10.2.5.6", "10.2.5.7", "10.2.5.8", "10.2.5.9", "10.2.5.10"]

現在我們就可以根據 CMDB 接口來動態生成主機列表了。具體見代碼吧

方法一：

#!/usr/bin/env python
#encoding=utf-8
import sys
import os
import requests


from fabric.api import env
from fabric.api import run
from fabric.api import put
from fabric.api import execute
from fabric.api import roles
from fabric.api import parallel
from fabric.api import cd
from fabric.api import task

env.user = "test"
env.password = "test"



cmdburl = "http://cmdb.test.com/test/listServer.do"


def find_ips_by_domain(domain_name):
     ips=[]
     payload={"domain":domain_name}
     res = requests.get(cmdburl, params=payload)
     hosts=res.json()["object"][0]["servers"]
     for host in hosts:
         host_ip=host["ip"]
         ips.append(host_ip)
     return ips 




def do_work():
    run("echo "Running stress test..."")

@task
def set_hosts(domain):
    # Update env.hosts instead of calling execute()
    host_list = find_ips_by_domain(domain)
    execute(do_work, hosts=host_list)

# 調用
fab set_hosts:app
fab set_hosts:db

方法二：

#!/usr/bin/env python
#encoding=utf-8
import sys
import os
import requests

from fabric.api import env
from fabric.api import run
from fabric.api import put
from fabric.api import execute
from fabric.api import roles
from fabric.api import parallel
from fabric.api import cd
from fabric.api import task

env.user = "test"
env.password = "test"



cmdburl = "http://cmdb.test.com/test/listServer.do"


def find_ips_by_domain(domain_name):
     ips=[]
     payload={"domain":domain_name}
     res = requests.get(cmdburl, params=payload)
     hosts=res.json()["object"][0]["servers"]
     for host in hosts:
         host_ip=host["ip"]
         ips.append(host_ip)
     return ips 



@task
def do_work():
    run("echo "Running stress test..."")

@task
def set_hosts(domain):
    # Update env.hosts instead of calling execute()
    env.hosts = find_ips_by_domain(domain)

#調用
fab set_hosts:test.com do_work

上面兩種方法的區別是，第二種方法更容易替換執行其他任務

#!/usr/bin/env python
#encoding=utf-8
import sys
import os
import requests

from fabric.api import env
from fabric.api import run
from fabric.api import put
from fabric.api import execute
from fabric.api import roles
from fabric.api import parallel
from fabric.api import cd
from fabric.api import task

env.user = "test"
env.password = "test"


cmdburl = "http://cmdb.test.com/test/listServer.do"

## 根據域名（服務名）查詢該域的所有服務器列表
def find_ips_by_domain(domain_name):
     ips=[]
     payload={"domain":domain_name}
     res = requests.get(cmdburl, params=payload)
     hosts=res.json()["object"][0]["servers"]
     for host in hosts:
         host_ip=host["ip"]
         ips.append(host_ip)
     return ips 

@task
def gener_roles(domain_name):
    ips = find_ips_by_domain(domain_name)  
    ### 動態生成角色列表
    **env.roledefs["ips"] = map(lambda x: x, ips)**
    ### 根據生成的角色列表處理任務
    execute(do_work)

@roles("ips")
def do_work():
    run("echo "Running stress test..."")

執行任務的方式為：

 fab gener_roles:test.com

Using execute with dynamically-set host lists

http://my.oschina.net/indestiny/blog/290239