# 函式計算
阿里雲[函式計算](https://help.aliyun.com/document_detail/52895.html?spm=a2c4g.11186623.6.539.AdoN1O)是一個事件驅動的全託管計算服務。透過函式計算，您無需管理伺服器等基礎設施，只需編寫程式碼並上傳。函式計算會為您準備好計算資源，以彈性、可靠的方式執行您的程式碼，並提供日誌查詢，效能監控，報警等功能。藉助於函式計算，您可以快速構建任何型別的應用和服務，無需管理和運維。更棒的是，您只需要為程式碼實際執行消耗的資源付費，而程式碼未執行則不產生費用。

# 雲監控
阿里雲[雲監控](https://help.aliyun.com/document_detail/35170.html?spm=a2c4g.11186623.6.541.1aae3846sRz4Rb)為雲上使用者提供開箱即用的企業級開放型一站式監控解決方案。涵蓋IT設施基礎監控，外網網路質量撥測監控，基於事件、自定義指標、日誌的業務監控。為您全方位提供更高效、更全面、更省錢的監控服務。<br>雲監控提供了豐富事件，並且事件還在不斷豐富中（[雲產品系統事件監控](https://help.aliyun.com/document_detail/66940.html?spm=a2c4g.11186623.6.644.7f1d6db3pfgDf3)）， 豐富的事件觸發自定義處理的函式，可以實現更加完美的的自動化運維。

## 專題傳送門 => [函式計算進行自動化運維專題](https://yq.aliyun.com/articles/581073)

# 示例場景
在本文中，重點關注函式計算對ecs的重啟事件處理，因為這些ecs重啟事件是目前使用者需要很高優先順序使用者優先順序去響應的；假設之前一臺ecs 發生因系統錯誤而重啟，使用者可能會緊急起來做一些驗證或者建立快照的處理， 在本示例中，我們對一臺因為系統錯誤例項重啟或者因例項錯誤而重啟的機器進行自動化處理，比如成功重啟後建立快照處理。

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

[雲產品系統事件監控](https://help.aliyun.com/document_detail/66940.html?spm=a2c4g.11186623.6.644.7f1d6db3pfgDf3)
![2](https://yqfile.alicdn.com/24e706ab04aafd1baed544571b5e6956462fb41c.png)

# 操作步驟

- 建立函式(函式程式碼在文末),函式建立可參考[函式計算helloworld](https://yq.aliyun.com/articles/226545?spm=a2c4g.11186623.2.3.sIm7jp)
> 注：記得給函式的service的role設定操作ecs的許可權

![3](https://yqfile.alicdn.com/a9aadfdf81f6ef4dd26f8053ee4e52299691783e.png)

- 登入[雲監控控制檯](https://cloudmonitor.console.aliyun.com/), 建立報警規則, 監控的事件為ecs 因例項錯誤或西戎錯誤重啟開始和結束
![4](https://yqfile.alicdn.com/aa106a9216361cce089ba1b1e851252c044ba12f.png)

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

- mock除錯
![7](https://yqfile.alicdn.com/66f42c2d910565dac54392154c1e306d4646cf63.png)
![8](https://yqfile.alicdn.com/56243348976b51cbc1be870858f523f563421630.png)

- 模擬真實的ecs事件<br>請參考[演練系統事件處理程式？ So Easy~](https://yq.aliyun.com/articles/627964)

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

## 程式碼
```
# -*- 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)
```

函式計算自動化運維實戰3 -- 事件觸發自動建立快照

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