如何在AWS Lambda中使用python访问事件对象？

就这一问题采取后续行动：

我认为这个问题不完整，因为它没有说明如何使用python访问事件对象

我的目标是：

• 读取由运行状态更改触发的实例
• 获取与实例关联的标记值
• 启动具有相同标记的所有其他实例

Cloudwatch触发事件是：

{
  "source": [
    "aws.ec2"
  ],
  "detail-type": [
    "EC2 Instance State-change Notification"
  ],
  "detail": {
    "state": [
      "running"
    ]
  }
}

我可以看到这样的例子：

def lambda_handler(event, context):

    # here I want to get the instance tag value
    # and set the tag filter based on the instance that 
    # triggered the event

    filters = [{
            'Name': 'tag:StartGroup',
            'Values': ['startgroup1'] 
        },
        {
            'Name': 'instance-state-name', 
            'Values': ['running']
        }
    ]

    instances = ec2.instances.filter(Filters=filters)

我可以看到event对象，但看不到如何深入到状态更改为running的实例的标记

请问，我可以通过什么对象属性从触发的实例获取标记

我怀疑是这样的：

myTag = event.details.instance-id.tags["startgroup1"]

---

在事件的详细信息部分，您将获得实例Id。使用实例id和AWS SDK可以查询标记。下面是示例事件

{
  "version": "0",
  "id": "ee376907-2647-4179-9203-343cfb3017a4",
  "detail-type": "EC2 Instance State-change Notification",
  "source": "aws.ec2",
  "account": "123456789012",
  "time": "2015-11-11T21:30:34Z",
  "region": "us-east-1",
  "resources": [
    "arn:aws:ec2:us-east-1:123456789012:instance/i-abcd1111"
  ],
  "detail": {
    "instance-id": "i-abcd1111",
    "state": "running"
  }
}

---

传递给Lambda的事件数据包含实例ID

然后需要调用

descripe_tags（）

来检索标签字典

import boto3
client = boto3.client('ec2')

client.describe_tags(Filters=[
        {
            'Name': 'resource-id',
            'Values': [
                event['detail']['instance-id']
            ]
        }
    ]
)

---

这就是我想到的

请让我知道如何做得更好。谢谢你的帮助

# StartMeUp_Instances_byOne
#
# This lambda script is triggered by a CloudWatch Event, startGroupByInstance.
# Every evening a separate lambda script is launched on a schedule to stop
# all non-essential instances.
# 
# This script will turn on all instances with a LaunchGroup tag that matches 
# a single instance which has been changed to the running state.
#
# To start all instances in a LaunchGroup, 
# start one of the instances in the LaunchGroup and wait about 5 minutes.
# 
# Costs to run: approx. $0.02/month
# https://s3.amazonaws.com/lambda-tools/pricing-calculator.html
# 150 executions per month * 128 MB Memory * 60000 ms Execution Time
# 
# Problems: talk to chrisj
# ======================================

# test system
# this is what the event object looks like (see below)
# it is configured in the test event object with a specific instance-id
# change that to test a different instance-id with a different LaunchGroup

# {  "version": "0",
#   "id": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
#   "detail-type": "EC2 Instance State-change Notification",
#   "source": "aws.ec2",
#   "account": "999999999999999",
#   "time": "2015-11-11T21:30:34Z",
#   "region": "us-east-1",
#   "resources": [
#     "arn:aws:ec2:us-east-1:123456789012:instance/i-abcd1111"
#   ],
#   "detail": {
#     "instance-id": "i-0aad9474",  # <---------- chg this
#     "state": "running"
#   }
# }
# ======================================

import boto3
import logging
import json

ec2 = boto3.resource('ec2')

def get_instance_LaunchGroup(iid):
    # When given an instance ID as str e.g. 'i-1234567', 
    # return the instance LaunchGroup.
    ec2 = boto3.resource('ec2')
    ec2instance = ec2.Instance(iid)
    thisTag = ''
    for tags in ec2instance.tags:
        if tags["Key"] == 'LaunchGroup':
            thisTag = tags["Value"]
    return thisTag

# this is the entry point for the cloudwatch trigger
def lambda_handler(event, context):

    # get the instance id that triggered the event
    thisInstanceID = event['detail']['instance-id']
    print("instance-id: " + thisInstanceID)

    # get the LaunchGroup tag value of the thisInstanceID
    thisLaunchGroup = get_instance_LaunchGroup(thisInstanceID)
    print("LaunchGroup: " + thisLaunchGroup)
    if thisLaunchGroup == '':
        print("No LaunchGroup associated with this InstanceID - ending lambda function")
        return

    # set the filters
    filters = [{
            'Name': 'tag:LaunchGroup',
            'Values': [thisLaunchGroup] 
        },
        {
            'Name': 'instance-state-name', 
            'Values': ['stopped']
        }
    ]

    # get the instances based on the filter, thisLaunchGroup and stopped
    instances = ec2.instances.filter(Filters=filters)

    # get the stopped instance IDs
    stoppedInstances = [instance.id for instance in instances]

    # make sure there are some instances not already started
    if len(stoppedInstances) > 0:
        startingUp = ec2.instances.filter(InstanceIds=stoppedInstances).start()

    print ("Finished launching all instances for tag: " + thisLaunchGroup)

#逐个启动MEUP#U实例
#
#此lambda脚本由CloudWatch事件startGroupByInstance触发。
#每天晚上，一个单独的lambda脚本按计划启动以停止
#所有非必要的实例。
# 
#此脚本将打开具有匹配的LaunchGroup标记的所有实例
#已更改为运行状态的单个实例。
#
#要启动启动组中的所有实例，
#启动LaunchGroup中的一个实例并等待大约5分钟。
# 
#运行成本：约0.02美元/月
# https://s3.amazonaws.com/lambda-tools/pricing-calculator.html
#每月执行150次*128 MB内存*60000毫秒执行时间
# 
#问题：与克里斯对话
# ======================================
#测试系统
#这就是事件对象的外观（见下文）
#它在测试事件对象中使用特定实例id进行配置
#将其更改为使用不同的启动组测试不同的实例id
#{“版本”：“0”，
#“id”：“XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX”，
#“详细信息类型”：“EC2实例状态更改通知”，
#“来源”：“aws.ec2”，
#“账户”：“999999999999”，
#“时间”：“2015-11-11T21:30:34Z”，
#“区域”：“us-east-1”，
#“资源”：[
#“arn:aws:ec2:us-east-1:123456789012:instance/i-abcd1111”
#   ],
#“细节”：{
#“实例id”：“i-0aad9474”，#0:
startingUp=ec2.instances.filter（instanceId=stoppedInstances.start（））
打印（“已完成启动标记“+thisLaunchGroup”的所有实例）

因此，下面是如何在Python代码中为Lambda函数获取标记的

  ec2 = boto3.resource('ec2')
  instance = ec2.Instance(instanceId)

# get image_id from instance-id
  imageId = instance.image_id
  print(imageId)

  for tags in instance.tags:
    if tags["Key"] == 'Name':
      newName = tags["Value"] + ".mydomain.com"
  print(newName)

---

因此，使用

instance.tags

，然后检查与我的

Name

标记匹配的

“Key”

，并拉出

“Value”

，以创建FQDN（完全限定域名）.

谢谢，Vaisakh。这实际上很有帮助。我看到了事件对象和详细信息部分，但请注意，如何使用python获取此实例id的特定标记。这是一个json解析练习吗？还是可以使用对象属性来完成？实例的标记值似乎不在事件对象中。谢谢，Chris、 John，我在boto3文档中看到了对客户端对象的引用，但没有看到descripe_tags方法。我已经发布了我的工作（可能不是最好的）代码。虽然在使用不存在的实例id进行测试时会抛出错误，但它工作得很快。我认为这没关系，因为我可能不会从不存在的实例列表中启动实例。实际上，我认为它可能会被终止，仍然在列表中，并且我意外地选择了它。哦，好吧。