使用 boto3 从 S3 存储桶中读取文件内容

Question

我通过

读取了 S3 存储桶中的文件名

objs = boto3.client.list_objects(Bucket='my_bucket')
    while 'Contents' in objs.keys():
        objs_contents = objs['Contents']
        for i in range(len(objs_contents)):
            filename = objs_contents[i]['Key']

现在，我需要获取文件的实际内容，类似于 open(filename).readlines()。什么是最好的方法？

Answer 1

boto3 提供了一种资源模型，可以使遍历对象等任务变得更加容易。不幸的是，StreamingBody 不提供 readline 或 readlines。

s3 = boto3.resource('s3')
bucket = s3.Bucket('test-bucket')
# Iterates through all the objects, doing the pagination for you. Each obj
# is an ObjectSummary, so it doesn't contain the body. You'll need to call
# get to get the whole body.
for obj in bucket.objects.all():
    key = obj.key
    body = obj.get()['Body'].read()

Answer 2

当您想读取一个配置与默认配置不同的文件时，可以直接使用 mpu.aws.s3_read(s3path) 或复制粘贴代码：

def s3_read(source, profile_name=None):
    """
    Read a file from an S3 source.

    Parameters
    ----------
    source : str
        Path starting with s3://, e.g. 's3://bucket-name/key/foo.bar'
    profile_name : str, optional
        AWS profile

    Returns
    -------
    content : bytes

    botocore.exceptions.NoCredentialsError
        Botocore is not able to find your credentials. Either specify
        profile_name or add the environment variables AWS_ACCESS_KEY_ID,
        AWS_SECRET_ACCESS_KEY and AWS_SESSION_TOKEN.
        See https://boto3.readthedocs.io/en/latest/guide/configuration.html
    """
    session = boto3.Session(profile_name=profile_name)
    s3 = session.client('s3')
    bucket_name, key = mpu.aws._s3_path_split(source)
    s3_object = s3.get_object(Bucket=bucket_name, Key=key)
    body = s3_object['Body']
    return body.read()

Answer 3

您可以考虑 smart_open 模块，它支持迭代器：

from smart_open import smart_open

# stream lines from an S3 object
for line in smart_open('s3://mybucket/mykey.txt', 'rb'):
    print(line.decode('utf8'))

和上下文管理器：

with smart_open('s3://mybucket/mykey.txt', 'rb') as s3_source:
    for line in s3_source:
         print(line.decode('utf8'))

    s3_source.seek(0)  # seek to the beginning
    b1000 = s3_source.read(1000)  # read 1000 bytes

在 https://pypi.org/project/smart_open/

找到 smart_open

Answer 4

如果您已经知道 filename，您可以使用 boto3 内置 download_fileobj

import boto3

from io import BytesIO

session = boto3.Session()
s3_client = session.client("s3")

f = BytesIO()
s3_client.download_fileobj("bucket_name", "filename", f)
print(f.getvalue())

Answer 5

使用客户端而不是资源：

s3 = boto3.client('s3')
bucket='bucket_name'
result = s3.list_objects(Bucket = bucket, Prefix='/something/')
for o in result.get('Contents'):
    data = s3.get_object(Bucket=bucket, Key=o.get('Key'))
    contents = data['Body'].read()
    print(contents.decode("utf-8"))

Answer 6

对我来说最好的方法是：

result = s3.list_objects(Bucket = s3_bucket, Prefix=s3_key)
for file in result.get('Contents'):
    data = s3.get_object(Bucket=s3_bucket, Key=file.get('Key'))
    contents = data['Body'].read()
    #if Float types are not supported with dynamodb; use Decimal types instead
    j = json.loads(contents, parse_float=Decimal)
    for item in j:
       timestamp = item['timestamp']

       table.put_item(
           Item={
            'timestamp': timestamp
           }
      )

一旦你有了内容，你就可以运行通过另一个循环将它写入 dynamodb table 例如...

使用 boto3 从 S3 存储桶中读取文件内容

Read file content from S3 bucket with boto3

python

amazon-s3

amazon-web-services

boto3