如何过滤Boto3 client.describe_volumes响应提取指定字段？

问题描述 #

我正在尝试使用Boto3从EBS卷中提取Device、InstanceId和AvailabilityZone字段。

现有代码：

import boto3

AWS_REGION = "us-east-1"
client = boto3.client('ec2', region_name=AWS_REGION)


volume_id_list = ['vol-02e15c9d70exxxxx', 'vol-0bbcb1b0e98xxxxx'] 


for vol_id in volume_id_list:

    response = client.describe_volumes(
        VolumeIds=[
        vol_id,
        ],
    )

    print(response)

调用后得到的响应格式复杂，虽然包含目标数据，但无法直接提取：

{'Volumes': [{'Attachments': [{'AttachTime': datetime.datetime(2022, 11, 23, 18, 18, 9, tzinfo=tzutc()), 'Device': '/dev/xvda', 'InstanceId': 'i-xxxxxxxxxxx', 'State': 'attached', 'VolumeId': 'vol-02e15c9xxxxxxx', 'DeleteOnTermination': True}], 'AvailabilityZone': 'us-east-1a', 'CreateTime': datetime.datetime(2022, 11, 23, 18, 18, 9, 713000, tzinfo=tzutc()), 'Encrypted': False, 'Size': 8, 'SnapshotId': 'snap-xxxxxxxxxxx', 'State': 'in-use', 'VolumeId': 'vol-xxxxxxxxxxx', 'Iops': 100, 'VolumeType': 'gp2', 'MultiAttachEnabled': False}], 'ResponseMetadata': {'RequestId': 'xxxxxxx-eb66-4be9-a2c6-0xxxxxxxxx', 'HTTPStatusCode': 200, 'HTTPHeaders': {'x-amzn-requestid': 'xxxxxx-eb66-4be9-a2c6-xxxxxxxx', 'cache-control': 'no-cache, no-store', 'strict-transport-security': 'max-age=31536000; includeSubDomains', 'content-type': 'text/xml;charset=UTF-8', 'content-length': '1201', 'date': 'Wed, 07 Dec 2022 17:07:50 GMT', 'server': 'AmazonEC2'}, 'RetryAttempts': 0}}

请问是否有办法过滤该响应，仅获取Device、InstanceId和AvailabilityZone字段？

解决方案 #

你可以通过逐层遍历响应的嵌套字典和列表结构来提取目标字段，以下是优化后的代码：

通用版（支持多实例挂载场景） #

import boto3

AWS_REGION = "us-east-1"
client = boto3.client('ec2', region_name=AWS_REGION)

volume_id_list = ['vol-02e15c9d70exxxxx', 'vol-0bbcb1b0e98xxxxx'] 

for vol_id in volume_id_list:
    response = client.describe_volumes(VolumeIds=[vol_id])
    # 遍历每个卷的信息
    for volume in response['Volumes']:
        availability_zone = volume['AvailabilityZone']
        # 遍历卷的所有挂载记录
        for attachment in volume['Attachments']:
            device = attachment['Device']
            instance_id = attachment['InstanceId']
            
            # 输出提取结果
            print(f"Volume ID: {vol_id}")
            print(f"Device: {device}")
            print(f"InstanceId: {instance_id}")
            print(f"AvailabilityZone: {availability_zone}\n")

简化版（仅单实例挂载场景） #

如果你的EBS卷只会挂载到一个EC2实例，可以直接通过索引取值，简化代码：

import boto3

AWS_REGION = "us-east-1"
client = boto3.client('ec2', region_name=AWS_REGION)

volume_id_list = ['vol-02e15c9d70exxxxx', 'vol-0bbcb1b0e98xxxxx'] 

for vol_id in volume_id_list:
    response = client.describe_volumes(VolumeIds=[vol_id])
    volume = response['Volumes'][0]
    attachment = volume['Attachments'][0]
    
    device = attachment['Device']
    instance_id = attachment['InstanceId']
    availability_zone = volume['AvailabilityZone']
    
    print(f"Device: {device}, InstanceId: {instance_id}, AvailabilityZone: {availability_zone}")

关键说明 #

• 响应的顶层结构是Volumes列表，每个元素对应一个EBS卷的完整信息字典
• AvailabilityZone直接存储在卷信息字典中，可直接提取
• Device和InstanceId存储在卷信息字典的Attachments列表里，每个列表元素对应一条挂载记录，因此需要遍历（或通过索引定位）该列表来获取字段

内容的提问来源于stack exchange，提问作者Naxxio