Django【设计】可插拔的插件方式实现
需求：
在CMDB系统中，我们需要对资产进行采集和资产入库，包括serverBasic、disk、memory、nic信息等，客户端需要采集这些硬件的信息，服务端则负责资产入库，但是需要采集的硬件并不是固定不变的，我们需要根据实际情况适当的添加或者减少硬件信息的采集，所以在生产环境中，我们把每个硬件信息的采集和入库做成插件，相互独立，可在配置文件中增减或者移除。
知识点：
字符串的形式导入插件方式：（字符串的格式也就是插件这个类的路径，这种格式正好也是类的导入格式）
# 根据字符串形式导入模块，并且找到其中的类并执行
import importlib
v = "src.plugins.nic.Nic"
module_path,cls_name = v.rsplit('.',maxsplit=1)
m = importlib.import_module(module_path)
cls = getattr(m,cls_name)
obj = cls()
obj.process()
设计： （参考django中间件的加载方式）
在settings配置文件中做好插件配置，在加载插件的方法中，使用字符串形式导入类的方法，循环加载各个插件。
settings.py
plugins/__init__.py下的加载插件方法：
def exec_plugin(self): server_info = {} for k,v in self.plugin_items.items(): # 找到v字符串：src.plugins.nic.Nic， # src.plugins.disk.Disk info = {'status':True,'data': None,'msg':None} try: module_path,cls_name = v.rsplit('.',maxsplit=1) module = importlib.import_module(module_path) cls = getattr(module,cls_name) if hasattr(cls,'initial'): obj = cls.initial() else: obj = cls() ret = obj.process(self.exec_cmd,self.test) info['data'] = ret except Exception as e: info['status'] = False info['msg'] = traceback.format_exc() server_info[k] = info return server_info
应用实例（及整个业务逻辑）：
客户端：
执行流程：run.py >> script.py >> client.py >> plugins
run.py，设置全局变量，主函数启动
import sys import os BASEDIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__))) sys.path.append(BASEDIR) # 设置全局变量（手动配置路径） os.environ['AUTO_CLIENT_SETTINGS'] = "conf.settings" # # 导入插件管理类 # from src.plugins import PluginManager from src import script if __name__ == '__main__': script.start()
script.py，约束采集信息模式(agent,ssh,salt)，兼容三种模式
from lib.config import settings from .client import AgentClient from .client import SaltSshClient def start(): # 这个函数用来判断模式，并约束可选模式 if settings.MODE == 'AGENT': obj = AgentClient() elif settings.MODE == "SSH" or settings.MODE == 'SALT': obj = SaltSshClient() else: raise Exception('模式仅支持：AGENT/SSH/SALT') obj.exec()
client.py，三种模式的调用插件，API验证
import requests,json,time,hashlib from src.plugins import PluginManager from lib.config import settings from concurrent.futures import ThreadPoolExecutor class BaseClient(object): def __init__(self): self.api = settings.API def post_server_info(self,server_dict): # requests.post(self.api,data=server_dict) # 1. k=v&k=v, 2. content-type: application/x-www-form-urlencoded response = requests.post(self.api,json=server_dict,headers={'auth-api':auth_header_val}) # 1. 字典序列化；2. 带请求头 content-type: application/json def exec(self): raise NotImplementedError('必须实现exec方法') class AgentClient(BaseClient): # 继承BaseClient类 def exec(self): obj = PluginManager() server_dict = obj.exec_plugin() print('采集到的服务器信息：',server_dict) self.post_server_info(server_dict) class SaltSshClient(BaseClient): # 继承BaseClient类 def task(self,host): obj = PluginManager(host) server_dict = obj.exec_plugin() self.post_server_info(server_dict) def get_host_list(self): response = requests.get(self.api,headers={'auth-api':auth_header_val}) print(response.text) # [{"hostname":"c1.com"}] return json.loads(response.text) # return ['c1.com',] def exec(self): pool = ThreadPoolExecutor(10) host_list = self.get_host_list() for host in host_list: # 注意格式，如果host_list为字典，用host.hostname取值 pool.submit(self.task,host)
plugins
__init__.py，初始化插件
import importlib import requests from lib.config import settings import traceback class PluginManager(object): def __init__(self,hostname=None): self.hostname = hostname self.plugin_items = settings.PLUGIN_ITEMS self.mode = settings.MODE self.test = settings.TEST if self.mode == "SSH": self.ssh_user = settings.SSH_USER self.ssh_port = settings.SSH_PORT self.ssh_pwd = settings.SSH_PWD def exec_plugin(self): server_info = {} for k,v in self.plugin_items.items(): # 找到v字符串：src.plugins.nic.Nic， # src.plugins.disk.Disk info = {'status':True,'data': None,'msg':None} try: module_path,cls_name = v.rsplit('.',maxsplit=1) module = importlib.import_module(module_path) cls = getattr(module,cls_name) if hasattr(cls,'initial'): obj = cls.initial() else: obj = cls() ret = obj.process(self.exec_cmd,self.test) info['data'] = ret except Exception as e: info['status'] = False info['msg'] = traceback.format_exc() server_info[k] = info return server_info def exec_cmd(self,cmd): # 调用插件方法时，会把执行命令的方法作为参数传到插件，line:48 if self.mode == "AGENT": import subprocess result = subprocess.getoutput(cmd) elif self.mode == "SSH": import paramiko ssh = paramiko.SSHClient() ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy()) ssh.connect(hostname=self.hostname, port=self.ssh_port, username=self.ssh_user, password=self.ssh_pwd) stdin, stdout, stderr = ssh.exec_command(cmd) result = stdout.read() ssh.close() elif self.mode == "SALT": import subprocess result = subprocess.getoutput('salt "%s" cmd.run "%s"' %(self.hostname,cmd)) else: raise Exception("模式选择错误：AGENT,SSH,SALT") return result
服务端：
执行流程：views.py >> plugins
settings.py
PLUGIN_ITEMS = { "nic": "api.plugins.nic.Nic", "disk": "api.plugins.disk.Disk", "memory": "api.plugins.memory.Memory", }
views.py：获取未采集列表，调用写入数据库插件
manager = PluginManager() response = manager.exec(server_dict) return HttpResponse(json.dumps(response))
plugins
__init__.py，初始化插件
for k,v in self.plugin_items.items(): print(k,v) # try: module_path,cls_name = v.rsplit('.',maxsplit=1) md = importlib.import_module(module_path) cls = getattr(md,cls_name) obj = cls(server_obj,server_dict[k]) obj.process() print(k,v)
