# 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
假設兩臺ECS機器A, B, A 機器出現了當機，這個時候需要把A機器上的eip遷移到備用機器B上，這個利用雲監控的報警和函式計算可以實現EIP的自動遷移， 雲監控檢測到A當機這個事件，然後觸發函式執行，函式實現eip的自動遷移

# 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和eip的許可權
![1](https://yqfile.alicdn.com/969096ef4233ea658e1ccf75686a7c4620269329.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 重啟開始

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

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

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

- mock除錯

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

![6](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)

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

## 程式碼
```
# -*- 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)
```

函式計算自動化運維實戰2 -- 事件觸發eip自動轉移

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