Read file content from S3 bucket with boto3
PythonAmazon Web-ServicesAmazon S3Boto3Python Problem Overview
I read the filenames in my S3 bucket by doing
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']
Now, I need to get the actual content of the file, similarly to a open(filename).readlines()
. What is the best way?
Python Solutions
Solution 1 - Python
boto3 offers a resource model that makes tasks like iterating through objects easier. Unfortunately, StreamingBody doesn't provide readline
or 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()
Solution 2 - Python
You might consider the smart_open
module, which supports iterators:
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'))
and context managers:
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
Find smart_open
at https://pypi.org/project/smart_open/
Solution 3 - Python
Using the client instead of resource:
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"))
Solution 4 - Python
When you want to read a file with a different configuration than the default one, feel free to use either mpu.aws.s3_read(s3path)
directly or the copy-pasted code:
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()
Solution 5 - Python
If you already know the filename
, you can use the boto3
builtin 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())
Solution 6 - Python
the best way for me is this:
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
}
)
once you have the content you can run it through another loop to write it to a dynamodb table for instance ...