如何使用boto3获取公网ip

Question

我需要从AWS提取所有运行的公共Ip，并使用以下代码：

def gather_public_ip():
    regions = ['us-west-2', 'eu-central-1', 'ap-southeast-1']
    combined_list = []   ##This needs to be returned
    for region in regions:
        instance_information = [] # I assume this is a list, not dict
        ip_dict = {}
        client = boto3.client('ec2', aws_access_key_id=ACCESS_KEY, aws_secret_access_key=SECRET_KEY,
                              region_name=region, )
        instance_dict = client.describe_instances().get('Reservations')
        for reservation in instance_dict:
            for instance in reservation['Instances']: # This is rather not obvious
               if instance[unicode('State')][unicode('Name')] == 'running' and instance[unicode('PublicIpAddress')] != None:
                    ipaddress = instance[unicode('PublicIpAddress')]
                    tagValue = instance[unicode('Tags')][0][unicode('Value')] # 'Tags' is a list, took the first element, you might wanna switch this
                    zone = instance[unicode('Placement')][unicode('AvailabilityZone')]
                    info = ipaddress, tagValue, zone
                    instance_information.append(info)
        combined_list.append(instance_information)
    return combined_list

这对我不起作用，它给了我一个错误：

    ipaddress = instance[unicode('PublicIpAddress')]
KeyError: u'PublicIpAddress'

这个字典中不存在PublicIpAddress的原因..有谁能帮帮我吗？

Answer 1

使用get()而不是dict[key]。get()不会引发KeyError。这里有一些例子，它们将解释。

>>> test = {'xxx':123}
>>> test['xxx']
123
>>> test['yyy']
KeyError: 'yyy'
>>> test.get('yyy')
>>> test.get('yyy') is None
True

您可以检查'PublicIpAddress'是否不存在，如下所示。

ipaddress = instance.get(u'PublicIpAddress')
if ipaddress is None:
   # Do Something

编辑

if instance[u'State'][u'Name'] == 'running' and instance.get(u'PublicIpAddress') is not None:
    print instance.get(u'PublicIpAddress')