或者是类名的比较。

except ClientError as e:
    if 'EntityAlreadyExistsException' == e.__class__.__name__:
        # handle specific error

因为它们是动态创建的，所以永远不能导入类并使用真正的Python捕获它。

使用异常中包含的响应。这里有一个例子:

import boto3
from botocore.exceptions import ClientError

try:
    iam = boto3.client('iam')
    user = iam.create_user(UserName='fred')
    print("Created user: %s" % user)
except ClientError as e:
    if e.response['Error']['Code'] == 'EntityAlreadyExists':
        print("User already exists")
    else:
        print("Unexpected error: %s" % e)

异常中的响应字典将包含以下内容:

(“错误”)(“代码”)。'EntityAlreadyExists'或'ValidationError' [' responsemetdata ']['HTTPStatusCode']例:400 [“ResponseMetadata”][' RequestId ']。“d2b06652 - 88 - d7 - 11 - e5 - 99 - d0 - 812348583 - a35” (“错误”)(“信息”)。"发生错误(EntityAlreadyExists)…" ['错误']['类型']。“发送”

有关更多信息，请参阅:

Boto3错误处理 Botocore错误处理

(更新:2018-03-07)

AWS Python SDK已经开始公开客户端上的服务异常(虽然不是资源上的异常)，你可以显式地捕获这些异常，所以现在可以像这样编写代码:

import botocore
import boto3

try:
    iam = boto3.client('iam')
    user = iam.create_user(UserName='fred')
    print("Created user: %s" % user)
except iam.exceptions.EntityAlreadyExistsException:
    print("User already exists")
except botocore.exceptions.ParamValidationError as e:
    print("Parameter validation error: %s" % e)
except botocore.exceptions.ClientError as e:
    print("Unexpected error: %s" % e)

不幸的是，目前没有关于这些错误/异常的文档，但你可以得到一个核心错误列表，如下所示:

import botocore
import boto3
[e for e in dir(botocore.exceptions) if e.endswith('Error')]

注意，必须同时导入botocore和boto3。如果你只导入botocore，你会发现botocore没有名为exceptions的属性。这是因为异常被boto3动态地填充到botocore中。

您可以获得以下特定于服务的异常列表(根据需要将iam替换为相关的服务):

import boto3
iam = boto3.client('iam')
[e for e in dir(iam.exceptions) if e.endswith('Exception')]

(更新:2021-09-07)

除了前面提到的客户端异常方法之外，还有一个名为aws-error-utils的第三方帮助包。

只是更新了@jarmod指出的“资源上没有例外”问题(如果下面似乎适用，请随时更新您的答案)

我已经测试了下面的代码，它运行良好。它使用“资源”来做事情，但捕获客户端。例外-尽管它“看起来”有点错误…它测试得很好，在异常时使用调试器查看异常类时显示和匹配……

它可能不适用于所有资源和客户端，但适用于数据文件夹(又名s3桶)。

lab_session = boto3.Session() 
c = lab_session.client('s3') #this client is only for exception catching

try:
    b = s3.Bucket(bucket)
    b.delete()
except c.exceptions.NoSuchBucket as e:
    #ignoring no such bucket exceptions
    logger.debug("Failed deleting bucket. Continuing. {}".format(e))
except Exception as e:
    #logging all the others as warning
    logger.warning("Failed deleting bucket. Continuing. {}".format(e))

希望这对你有所帮助……

只需要一个导入。 不需要if语句。 按预期使用客户端内置异常。

Ex:

from boto3 import client

cli = client('iam')
try:
    cli.create_user(
        UserName = 'Brian'
    )
except cli.exceptions.EntityAlreadyExistsException:
    pass

CloudWatch示例:

cli = client('logs')
try:
    cli.create_log_group(
        logGroupName = 'MyLogGroup'
    )
except cli.exceptions.ResourceAlreadyExistsException:
    pass

如果您正在使用Python3调用sign_up API (AWS Cognito)，您可以使用以下代码。

def registerUser(userObj):
    ''' Registers the user to AWS Cognito.
    '''

    # Mobile number is not a mandatory field. 
    if(len(userObj['user_mob_no']) == 0):
        mobilenumber = ''
    else:
        mobilenumber = userObj['user_country_code']+userObj['user_mob_no']

    secretKey = bytes(settings.SOCIAL_AUTH_COGNITO_SECRET, 'latin-1')
    clientId = settings.SOCIAL_AUTH_COGNITO_KEY 

    digest = hmac.new(secretKey,
                msg=(userObj['user_name'] + clientId).encode('utf-8'),
                digestmod=hashlib.sha256
                ).digest()
    signature = base64.b64encode(digest).decode()

    client = boto3.client('cognito-idp', region_name='eu-west-1' ) 

    try:
        response = client.sign_up(
                    ClientId=clientId,
                    Username=userObj['user_name'],
                    Password=userObj['password1'],
                    SecretHash=signature,
                    UserAttributes=[
                        {
                            'Name': 'given_name',
                            'Value': userObj['given_name']
                        },
                        {
                            'Name': 'family_name',
                            'Value': userObj['family_name']
                        },
                        {
                            'Name': 'email',
                            'Value': userObj['user_email']
                        },
                        {
                            'Name': 'phone_number',
                            'Value': mobilenumber
                        }
                    ],
                    ValidationData=[
                        {
                            'Name': 'email',
                            'Value': userObj['user_email']
                        },
                    ]
                    ,
                    AnalyticsMetadata={
                        'AnalyticsEndpointId': 'string'
                    },
                    UserContextData={
                        'EncodedData': 'string'
                    }
                )
    except ClientError as error:
        return {"errorcode": error.response['Error']['Code'],
            "errormessage" : error.response['Error']['Message'] }
    except Exception as e:
        return {"errorcode": "Something went wrong. Try later or contact the admin" }
    return {"success": "User registered successfully. "}

错误。response['Error']['Code']将是InvalidPasswordException, UsernameExistsException等。因此，在主函数中或在调用函数的地方，可以编写逻辑以向用户提供有意义的消息。

一个响应(error.response)的例子:

{
  "Error": {
    "Message": "Password did not conform with policy: Password must have symbol characters",
    "Code": "InvalidPasswordException"
  },
  "ResponseMetadata": {
    "RequestId": "c8a591d5-8c51-4af9-8fad-b38b270c3ca2",
    "HTTPStatusCode": 400,
    "HTTPHeaders": {
      "date": "Wed, 17 Jul 2019 09:38:32 GMT",
      "content-type": "application/x-amz-json-1.1",
      "content-length": "124",
      "connection": "keep-alive",
      "x-amzn-requestid": "c8a591d5-8c51-4af9-8fad-b38b270c3ca2",
      "x-amzn-errortype": "InvalidPasswordException:",
      "x-amzn-errormessage": "Password did not conform with policy: Password must have symbol characters"
    },
    "RetryAttempts": 0
  }
}

如需进一步参考: https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/cognito-idp.html#CognitoIdentityProvider.Client.sign_up

或者是类名的比较。

except ClientError as e:
    if 'EntityAlreadyExistsException' == e.__class__.__name__:
        # handle specific error

因为它们是动态创建的，所以永远不能导入类并使用真正的Python捕获它。