# 函数计算
阿里云[函数计算](https://help.aliyun.com/document_detail/52895.html?spm=a2c4g.11186623.6.539.AdoN1O)是一个事件驱动的全托管计算服务。通过函数计算，您无需管理服务器等基础设施，只需编写代码并上传。函数计算会为您准备好计算资源，以弹性、可靠的方式运行您的代码，并提供日志查询，性能监控，报警等功能。借助于函数计算，您可以快速构建任何类型的应用和服务，无需管理和运维。更棒的是，您只需要为代码实际运行消耗的资源付费，而代码未运行则不产生费用。

# 云监控
阿里云[云监控](https://help.aliyun.com/document_detail/35170.html?spm=a2c4g.11186623.6.541.1aae3846sRz4Rb)为云上用户提供开箱即用的企业级开放型一站式监控解决方案。涵盖IT设施基础监控，外网网络质量拨测监控，基于事件、自定义指标、日志的业务监控。为您全方位提供更高效、更全面、更省钱的监控服务。<br />云监控提供了丰富事件，并且事件还在不断丰富中（[云产品系统事件监控](https://help.aliyun.com/document_detail/66940.html?spm=a2c4g.11186623.6.644.7f1d6db3pfgDf3)）， 丰富的事件触发自定义处理的函数，可以实现更加完美的的自动化运维。

## 专题传送门 => [函数计算进行自动化运维专题](https://yq.aliyun.com/articles/581073)

# 示例场景
假设两台ECS机器A, B, A 机器出现了宕机，这个时候需要把A机器上的eip迁移到备用机器B上，这个利用云监控的报警和函数计算可以实现EIP的自动迁移， 云监控检测到A宕机这个事件，然后触发函数执行，函数实现eip的自动迁移

# 操作步骤

- 创建函数(函数代码在文末),函数创建可参考[函数计算helloworld](https://yq.aliyun.com/articles/226545?spm=a2c4g.11186623.2.3.sIm7jp)
> 注：记得给函数的service的role设置操作ecs和eip的权限
![1](https://yqfile.alicdn.com/969096ef4233ea658e1ccf75686a7c4620269329.png)

- 登录[云监控控制台](https://cloudmonitor.console.aliyun.com/), 创建报警规则, 监控的事件为ecs 重启开始

![2](https://yqfile.alicdn.com/aa106a9216361cce089ba1b1e851252c044ba12f.png)

![3](https://yqfile.alicdn.com/b2ca42429c8774906ff672d3820c12faa8ac8a0c.png)

![4](https://yqfile.alicdn.com/9d38df1ab87c784e4d5eccb51b788a96f3e0dae9.png)

- mock调试

![5](https://yqfile.alicdn.com/66f42c2d910565dac54392154c1e306d4646cf63.png)

![6](https://yqfile.alicdn.com/56243348976b51cbc1be870858f523f563421630.png)

- 模拟真实的ecs事件<br />请参考[演练系统事件处理程序？ So Easy~](https://yq.aliyun.com/articles/627964)

![7](https://yqfile.alicdn.com/0f3ad88bde19c858c003c8bd9a7b8e3cc11a19d6.png)

## 代码
```
# -*- coding: utf-8 -*-
import logging
import json, random, string, time
from aliyunsdkcore import client
from aliyunsdkvpc.request.v20160428.AssociateEipAddressRequest import AssociateEipAddressRequest
from aliyunsdkvpc.request.v20160428.UnassociateEipAddressRequest import UnassociateEipAddressRequest
from aliyunsdkvpc.request.v20160428.DescribeEipAddressesRequest import DescribeEipAddressesRequest
from aliyunsdkcore.auth.credentials import StsTokenCredential
LOGGER = logging.getLogger()
clt = None
def handler(event, context):
  creds = context.credentials
  sts_token_credential = StsTokenCredential(creds.access_key_id, creds.access_key_secret, creds.security_token)
  '''
  {
    "product": "ECS",
    "content": {
        "executeFinishTime": "2018-06-08T01:25:37Z",
        "executeStartTime": "2018-06-08T01:23:37Z",
        "ecsInstanceName": "timewarp",
        "eventId": "e-t4nhcpqcu8fqushpn3mm",
        "eventType": "InstanceFailure.Reboot",
        "ecsInstanceId": "i-bp18l0uopocfc98xxxx" 
    },
    "resourceId": "acs:ecs:cn-hangzhou:123456789:instance/i-bp18l0uopocfc98xxxx",
    "level": "CRITICAL",
    "instanceName": "instanceName",
    "status": "Executing",
    "name": "Instance:SystemFailure.Reboot:Executing", 
    "regionId": "cn-hangzhou"
  }
  '''
  evt = json.loads(event)
  content = evt.get("content");
  ecsInstanceId = content.get("ecsInstanceId");
  regionId = evt.get("regionId");
  
  global clt
  clt = client.AcsClient(region_id=regionId, credential=sts_token_credential)
  
  name = evt.get("name");
  eipId = "eip-bp1nexxxc7zjfnex6i0";
  standbyEcsId = "i-bp19yycxx7yroukxpv"
  name = name.lower()
  
  if name in ['Disk:Stalled:Executing'.lower(), 'Instance:SystemFailure.Reboot:Executing'.lower(), "Instance:InstanceFailure.Reboot:Executing".lower()]:
    print("move eip to standbyEcs");
    move_eip(ecsInstanceId, standbyEcsId, eipId) # move eip to standbyEcs
  else:
    # other event to do 
    pass
  
def getEipStatus(eip):
  request = DescribeEipAddressesRequest()
  request.set_AllocationId(eip)
  request.add_query_param("RegionId", "cn-hangzhou")
  response = _send_request(request)
  if isinstance(response, dict) and "RequestId" in response:
    EipAddresses = response.get('EipAddresses', {})
    EipAddress = EipAddresses['EipAddress'][0]
    status = EipAddress['Status']
    return status
  else:
    LOGGER.error("getEipAddressDesc {} fail".format(eip))
def unAssociateEip(ecs_id, eip):
  request = UnassociateEipAddressRequest()
  request.set_AllocationId(eip)
  request.set_InstanceType('EcsInstance')
  request.set_InstanceId(ecs_id)
  response = _send_request(request)
  if isinstance(response, dict) and "RequestId" in response:
    LOGGER.info("UnassociateEipAddress {} from {} succ".format(ecs_id, eip))
  else:
    LOGGER.error("UnassociateEipAddress {} from {} fail".format(ecs_id, eip))
def associateEip(ecs_id, eip):
  associte_request = AssociateEipAddressRequest()
  associte_request.set_AllocationId(eip)
  associte_request.set_InstanceType('EcsInstance')
  associte_request.set_InstanceId(ecs_id)
  associte_response = _send_request(associte_request)
  if isinstance(associte_response, dict) and "RequestId" in associte_response:
    LOGGER.info("AssociateEipAddress {} to {} succ".format(eip, ecs_id))
    return True
  return False
def move_eip(from_ecs, to_ecs, eip):
  unAssociateEip(from_ecs, eip)
  # wait unAssociateEip ...
  time.sleep(3)
  # retry 30s util sucess
  for i in xrange(10):
    eip_status = getEipStatus(eip).lower()
    if eip_status == 'available':
      if associateEip(to_ecs, eip):
        LOGGER.info("AssociateEipAddress {} to {} succ".format(eip, to_ecs))
        return
    else:
      LOGGER.info("eip status = {}".format(eip_status))
      time.sleep(3)
  LOGGER.info("AssociateEipAddress {} to {} fail".format(eip, to_ecs))
# send open api request
def _send_request(request):
    request.set_accept_format('json')
    try:
        response_str = clt.do_action_with_exception(request)
        LOGGER.info(response_str)
        response_detail = json.loads(response_str)
        return response_detail
    except Exception as e:
        LOGGER.error(e)
```

ITPub博客

函数计算自动化运维实战2 -- 事件触发eip自动转移

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