# 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
在本文中，重点关注函数计算对ecs的重启事件处理，因为这些ecs重启事件是目前用户需要很高优先级用户优先级去响应的；假设之前一台ecs 发生因系统错误而重启，用户可能会紧急起来做一些验证或者创建快照的处理， 在本示例中，我们对一台因为系统错误实例重启或者因实例错误而重启的机器进行自动化处理，比如成功重启后创建快照处理。

[ecs 系统事件](https://help.aliyun.com/document_detail/66574.html)
![1](https://yqfile.alicdn.com/31eeef9826151824881ec02ea99b81c2962a640c.png)

[云产品系统事件监控](https://help.aliyun.com/document_detail/66940.html?spm=a2c4g.11186623.6.644.7f1d6db3pfgDf3)
![2](https://yqfile.alicdn.com/24e706ab04aafd1baed544571b5e6956462fb41c.png)

# 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的权限

![3](https://yqfile.alicdn.com/a9aadfdf81f6ef4dd26f8053ee4e52299691783e.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 因实例错误或西戎错误重启开始和结束
![4](https://yqfile.alicdn.com/aa106a9216361cce089ba1b1e851252c044ba12f.png)

![5](https://yqfile.alicdn.com/0f433297385ecb7f80742120ed1674a372766089.png)
![6](https://yqfile.alicdn.com/9d38df1ab87c784e4d5eccb51b788a96f3e0dae9.png)

- mock调试
![7](https://yqfile.alicdn.com/66f42c2d910565dac54392154c1e306d4646cf63.png)
![8](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)

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

## 代码
```
# -*- coding: utf-8 -*-
import logging
import json, random, string, time
from aliyunsdkcore import client
from aliyunsdkecs.request.v20140526.DeleteSnapshotRequest import DeleteSnapshotRequest
from aliyunsdkecs.request.v20140526.CreateSnapshotRequest import CreateSnapshotRequest
from aliyunsdkecs.request.v20140526.DescribeDisksRequest import DescribeDisksRequest
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");
  name = name.lower()
  if name in ['Instance:SystemFailure.Reboot:Executing'.lower(), "Instance:InstanceFailure.Reboot:Executing".lower()]:
    pass
    # do other things
  
  if name in ['Instance:SystemFailure.Reboot:Executed'.lower(), "Instance:InstanceFailure.Reboot:Executed".lower()]:
    request = DescribeDisksRequest()
    request.add_query_param("RegionId", "cn-shenzhen")
    request.set_InstanceId(ecsInstanceId)
    response = _send_request(request)
    disks = response.get('Disks').get('Disk', [])
    for disk in disks:
      diskId = disk["DiskId"]
      SnapshotId = create_ecs_snap_by_id(diskId)
      LOGGER.info("Create ecs snap sucess, ecs id = %s , disk id = %s ", ecsInstanceId, diskId)
    
def create_ecs_snap_by_id(disk_id):
    LOGGER.info("Create ecs snap, disk id is %s ", disk_id)
    request = CreateSnapshotRequest()
    request.set_DiskId(disk_id)
    request.set_SnapshotName("reboot_" + ''.join(random.choice(string.ascii_lowercase) for _ in range(6)))
    response = _send_request(request)
    return response.get("SnapshotId")
# 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3 -- 事件触发自动创建快照

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