Python 停止在环境变量中使用lambda的实例时发生客户端错误

我在环境变量中使用Lambda提供实例id来停止实例时遇到了客户端错误，但在硬编码实例id时工作正常

Lambda函数：

instances = ['i-0d66b89b8c010560d']

import boto3
import os
# Enter the region your instances are in. Include only the region without 
specifying Availability Zone; e.g., 'us-east-1'
region = 'us-east-1'
# Enter your instances here: ex. ['X-XXXXXXXX', 'X-XXXXXXXX']
# instances = ['i-0d66b89b8c010560d']

def lambda_handler(event, context):
    print 'stopping your instance'
    instances = os.environ['INSTANCES_ID']
    print instances
    print type(instances)
    instances = list(instances)
    print type(instances)
    ec2 = boto3.client('ec2', region_name=region)
    ec2.stop_instances(InstanceIds=instances)
    print 'stopped your instances: ' + str(instances)

日志输出：

START RequestId: 5c965493-fd10-11e8-9c0f-09f0c600ad35 Version: $LATEST
stopping your instance
i-0d66b89b8c010560d
<type 'str'>
<type 'tuple'>
An error occurred (InvalidInstanceID.Malformed) when calling the 
StopInstances operation: Invalid id: "i": ClientError
Traceback (most recent call last):
File "/var/task/lambda_function.py", line 18, in lambda_handler
ec2.stop_instances(InstanceIds=instances)
File "/var/runtime/botocore/client.py", line 314, in _api_call
return self._make_api_call(operation_name, kwargs)
File "/var/runtime/botocore/client.py", line 612, in _make_api_call
raise error_class(parsed_response, operation_name)
ClientError: An error occurred (InvalidInstanceID.Malformed) when calling  
the StopInstances operation: Invalid id: "i"

启动请求ID:5c965493-fd10-11e8-9c0f-09f0c600ad35版本：$LATEST
停止实例
i-0d66b89b8c010560d
调用时发生错误（InvalidInstanceID.Malformed）
StopInstances操作：无效id：“i”：ClientError
回溯（最近一次呼叫最后一次）：
lambda_处理程序中的文件“/var/task/lambda_function.py”，第18行
ec2.stop_实例（instanceId=instances）
文件“/var/runtime/botocore/client.py”，第314行，在api调用中
返回self.\u make\u api\u调用（操作名称，kwargs）
文件“/var/runtime/botocore/client.py”，第612行，在make\u api\u调用中
引发错误\u类（解析的\u响应、操作\u名称）
ClientError:调用时发生错误（InvalidInstanceID.Malformed）
StopInstances操作：无效id：“i”

正如您在日志输出中看到的，您的“实例”是一个str，其值为

i-0d66b89b8c010560d

。你可能不知道的是，str是可测试的。让列表“呼叫”的行为与您期望的不同。因此，当您调用此代码时：

instances = list(instances)

实际上，您正在这样做：

>>> instances = 'i-0d66b89b8c010560d'
>>> list(instances)
['i', '-', '0', 'd', '6', '6', 'b', '8', '9', 'b', '8', 'c', '0', '1', '0', '5', '6', '0', 'd']

看看会发生什么？您的str将转换为列表，其中str的每个索引都是列表中的索引

因此，解决办法是：

instances = ['i-0d66b89b8c010560d']

import boto3
import os
# Enter the region your instances are in. Include only the region without 
specifying Availability Zone; e.g., 'us-east-1'
region = 'us-east-1'
# Enter your instances here: ex. ['X-XXXXXXXX', 'X-XXXXXXXX']
# instances = ['i-0d66b89b8c010560d']

def lambda_handler(event, context):
    print 'stopping your instance'
    instances = os.environ['INSTANCES_ID']
    print instances
    print type(instances)
    instances = [instances]
    print type(instances)
    ec2 = boto3.client('ec2', region_name=region)
    ec2.stop_instances(InstanceIds=instances)
    print 'stopped your instances: ' + str(instances)