Python / Boto3 / 如何获得带有分页的标签列表？

Question

我想使用 boto3 获得一个 rds 和每个标签列表，没有 100 个限制。

这是获取 rds 列表和每个标签的代码。

client = boto3.client('rds')
instances = client.describe_db_instances()['DBInstances']

for i in instances:
    db_instance_name = i['DBInstanceIdentifier']
    arn = i['DBInstanceArn']
    tags = client.list_tags_for_resource(ResourceName=arn)
    for item in tags['TagList']:
        if item['Key'] == 'Name':
            print(db_instance_name,item['Value'])

这是分页的代码。

def all_rds_instances(page_size=20):
    client = session.client('rds')
    marker = ""
    pool = []
    while True:
        for instance in pool:
            yield instance
        if marker is None:
            break
        result = client.describe_db_instances(MaxRecords=page_size, Marker=marker)
        marker = result.get("Marker")
        pool = result.get("DBInstances")

我怎样才能结合这两个代码？

Answer 1

您只需要更改 for 循环以迭代您的 all_rds_instances 生成器。

您的脚本如下所示：

import boto3

client = boto3.client('rds')

def all_rds_instances(page_size=20):
    marker = ''
    pool = []
    while True:
        for instance in pool:
            yield instance
        if marker is None:
            break
        result = client.describe_db_instances(MaxRecords=page_size, Marker=marker)
        marker = result.get('Marker')
        pool = result.get('DBInstances')


for i in all_rds_instances():
    db_instance_name = i['DBInstanceIdentifier']
    arn = i['DBInstanceArn']
    tags = client.list_tags_for_resource(ResourceName=arn)
    for item in tags['TagList']:
        if item['Key'] == 'Name':
            print(db_instance_name, item['Value'])

当您使用yield关键字时，您的 function 将成为生成器，并且它的工作方式与 python 中的任何可迭代对象相同。

关于生成器如何在这里工作有一些很酷的答案