python - Listing contents of a bucket with boto3

Question

How can I see what's inside a bucket in S3 with boto3? (i.e. do an "ls")?

Doing the following:

import boto3
s3 = boto3.resource('s3')
my_bucket = s3.Bucket('some/path/')

returns:

s3.Bucket(name='some/path/')

How do I see its contents?

Answer 1

One way to see the contents would be:

for my_bucket_object in my_bucket.objects.all():
    print(my_bucket_object)

Answer 2

This is similar to an 'ls' but it does not take into account the prefix folder convention and will list the objects in the bucket. It's left up to the reader to filter out prefixes which are part of the Key name.

In Python 2:

from boto.s3.connection import S3Connection

conn = S3Connection() # assumes boto.cfg setup
bucket = conn.get_bucket('bucket_name')
for obj in bucket.get_all_keys():
    print(obj.key)

In Python 3:

from boto3 import client

conn = client('s3')  # again assumes boto.cfg setup, assume AWS S3
for key in conn.list_objects(Bucket='bucket_name')['Contents']:
    print(key['Key'])

Answer 3

I'm assuming you have configured authentication separately.

import boto3
s3 = boto3.resource('s3')

my_bucket = s3.Bucket('bucket_name')

for file in my_bucket.objects.all():
    print(file.key)

Answer 4

In order to handle large key listings (i.e. when the directory list is greater than 1000 items), I used the following code to accumulate key values (i.e. filenames) with multiple listings (thanks to Amelio above for the first lines). Code is for python3:

    from boto3  import client
    bucket_name = "my_bucket"
    prefix      = "my_key/sub_key/lots_o_files"

    s3_conn   = client('s3')  # type: BaseClient  ## again assumes boto.cfg setup, assume AWS S3
    s3_result =  s3_conn.list_objects_v2(Bucket=bucket_name, Prefix=prefix, Delimiter = "/")

    if 'Contents' not in s3_result:
        #print(s3_result)
        return []

    file_list = []
    for key in s3_result['Contents']:
        file_list.append(key['Key'])
    print(f"List count = {len(file_list)}")

    while s3_result['IsTruncated']:
        continuation_key = s3_result['NextContinuationToken']
        s3_result = s3_conn.list_objects_v2(Bucket=bucket_name, Prefix=prefix, Delimiter="/", ContinuationToken=continuation_key)
        for key in s3_result['Contents']:
            file_list.append(key['Key'])
        print(f"List count = {len(file_list)}")
    return file_list

Answer 5

My s3 keys utility function is essentially an optimized version of @Hephaestus's answer:

import boto3


s3_paginator = boto3.client('s3').get_paginator('list_objects_v2')


def keys(bucket_name, prefix='/', delimiter='/', start_after=''):
    prefix = prefix[1:] if prefix.startswith(delimiter) else prefix
    start_after = (start_after or prefix) if prefix.endswith(delimiter) else start_after
    for page in s3_paginator.paginate(Bucket=bucket_name, Prefix=prefix, StartAfter=start_after):
        for content in page.get('Contents', ()):
            yield content['Key']

In my tests (boto3 1.9.84), it's significantly faster than the equivalent (but simpler) code:

import boto3


def keys(bucket_name, prefix='/', delimiter='/'):
    prefix = prefix[1:] if prefix.startswith(delimiter) else prefix
    bucket = boto3.resource('s3').Bucket(bucket_name)
    return (_.key for _ in bucket.objects.filter(Prefix=prefix))

As S3 guarantees UTF-8 binary sorted results, a start_after optimization has been added to the first function.

Answer 6

If you want to pass the ACCESS and SECRET keys (which you should not do, because it is not secure):

from boto3.session import Session

ACCESS_KEY='your_access_key'
SECRET_KEY='your_secret_key'

session = Session(aws_access_key_id=ACCESS_KEY,
                  aws_secret_access_key=SECRET_KEY)
s3 = session.resource('s3')
your_bucket = s3.Bucket('your_bucket')

for s3_file in your_bucket.objects.all():
    print(s3_file.key)

Answer 7

A more parsimonious way, rather than iterating through via a for loop you could also just print the original object containing all files inside your S3 bucket:

session = Session(aws_access_key_id=aws_access_key_id,aws_secret_access_key=aws_secret_access_key)
s3 = session.resource('s3')
bucket = s3.Bucket('bucket_name')

files_in_s3 = bucket.objects.all() 
#you can print this iterable with print(list(files_in_s3))

Answer 8

ObjectSummary:

There are two identifiers that are attached to the ObjectSummary:

• bucket_name
• key

boto3 S3: ObjectSummary

More on Object Keys from AWS S3 Documentation:

Object Keys:

When you create an object, you specify the key name, which uniquely identifies the object in the bucket. For example, in the Amazon S3 console (see AWS Management Console), when you highlight a bucket, a list of objects in your bucket appears. These names are the object keys. The name for a key is a sequence of Unicode characters whose UTF-8 encoding is at most 1024 bytes long.

The Amazon S3 data model is a flat structure: you create a bucket, and the bucket stores objects. There is no hierarchy of subbuckets or subfolders; however, you can infer logical hierarchy using key name prefixes and delimiters as the Amazon S3 console does. The Amazon S3 console supports a concept of folders. Suppose that your bucket (admin-created) has four objects with the following object keys:

Development/Projects1.xls

Finance/statement1.pdf

Private/taxdocument.pdf

s3-dg.pdf

Reference:

AWS S3: Object Keys

Here is some example code that demonstrates how to get the bucket name and the object key.

Example:

import boto3
from pprint import pprint

def main():

    def enumerate_s3():
        s3 = boto3.resource('s3')
        for bucket in s3.buckets.all():
             print("Name: {}".format(bucket.name))
             print("Creation Date: {}".format(bucket.creation_date))
             for object in bucket.objects.all():
                 print("Object: {}".format(object))
                 print("Object bucket_name: {}".format(object.bucket_name))
                 print("Object key: {}".format(object.key))

    enumerate_s3()


if __name__ == '__main__':
    main()

Answer 9

Here is a simple function that returns you the filenames of all files or files with certain types such as 'json', 'jpg'.

def get_file_list_s3(bucket, prefix="", file_extension=None):
            """Return the list of all file paths (prefix + file name) with certain type or all
            Parameters
            ----------
            bucket: str
                The name of the bucket. For example, if your bucket is "s3://my_bucket" then it should be "my_bucket"
            prefix: str
                The full path to the the 'folder' of the files (objects). For example, if your files are in 
                s3://my_bucket/recipes/deserts then it should be "recipes/deserts". Default : ""
            file_extension: str
                The type of the files. If you want all, just leave it None. If you only want "json" files then it
                should be "json". Default: None       
            Return
            ------
            file_names: list
                The list of file names including the prefix
            """
            import boto3
            s3 = boto3.resource('s3')
            my_bucket = s3.Bucket(bucket)
            file_objs =  my_bucket.objects.filter(Prefix=prefix).all()
            file_names = [file_obj.key for file_obj in file_objs if file_extension is not None and file_obj.key.split(".")[-1] == file_extension]
            return file_names

Answer 10

I just did it like this, including the authentication method:

s3_client = boto3.client(
                's3',
                aws_access_key_id='access_key',
                aws_secret_access_key='access_key_secret',
                config=boto3.session.Config(signature_version='s3v4'),
                region_name='region'
            )

response = s3_client.list_objects(Bucket='bucket_name', Prefix=key)
if ('Contents' in response):
    # Object / key exists!
    return True
else:
    # Object / key DOES NOT exist!
    return False

Answer 11

#To print all filenames in a bucket
import boto3

s3 = boto3.client('s3')

def get_s3_keys(bucket):

    """Get a list of keys in an S3 bucket."""
    resp = s3.list_objects_v2(Bucket=bucket)
    for obj in resp['Contents']:
      files = obj['Key']
    return files


filename = get_s3_keys('your_bucket_name')

print(filename)

#To print all filenames in a certain directory in a bucket
import boto3

s3 = boto3.client('s3')

def get_s3_keys(bucket, prefix):

    """Get a list of keys in an S3 bucket."""
    resp = s3.list_objects_v2(Bucket=bucket, Prefix=prefix)
    for obj in resp['Contents']:
      files = obj['Key']
      print(files)
    return files


filename = get_s3_keys('your_bucket_name', 'folder_name/sub_folder_name/')

print(filename)

Answer 12

So you're asking for the equivalent of aws s3 ls in boto3. This would be listing all the top level folders and files. This is the closest I could get; it only lists all the top level folders. Surprising how difficult such a simple operation is.

import boto3

def s3_ls():
  s3 = boto3.resource('s3')
  bucket = s3.Bucket('example-bucket')
  result = bucket.meta.client.list_objects(Bucket=bucket.name,
                                           Delimiter='/')
  for o in result.get('CommonPrefixes'):
    print(o.get('Prefix'))

Answer 13

One way that I used to do this:

import boto3
s3 = boto3.resource('s3')
bucket=s3.Bucket("bucket_name")
contents = [_.key for _ in bucket.objects.all() if "subfolders/ifany/" in _.key]

Answer 14

With little modification to @Hephaeastus 's code in one of the above comments, wrote the below method to list down folders and objects (files) in a given path. Works similar to s3 ls command.

from boto3 import session

def s3_ls(profile=None, bucket_name=None, folder_path=None):
    folders=[]
    files=[]
    result=dict()
    bucket_name = bucket_name
    prefix= folder_path
    session = boto3.Session(profile_name=profile)
    s3_conn   = session.client('s3')
    s3_result =  s3_conn.list_objects_v2(Bucket=bucket_name, Delimiter = "/", Prefix=prefix)
    if 'Contents' not in s3_result and 'CommonPrefixes' not in s3_result:
        return []

    if s3_result.get('CommonPrefixes'):
        for folder in s3_result['CommonPrefixes']:
            folders.append(folder.get('Prefix'))

    if s3_result.get('Contents'):
        for key in s3_result['Contents']:
            files.append(key['Key'])

    while s3_result['IsTruncated']:
        continuation_key = s3_result['NextContinuationToken']
        s3_result = s3_conn.list_objects_v2(Bucket=bucket_name, Delimiter="/", ContinuationToken=continuation_key, Prefix=prefix)
        if s3_result.get('CommonPrefixes'):
            for folder in s3_result['CommonPrefixes']:
                folders.append(folder.get('Prefix'))
        if s3_result.get('Contents'):
            for key in s3_result['Contents']:
                files.append(key['Key'])

    if folders:
        result['folders']=sorted(folders)
    if files:
        result['files']=sorted(files)
    return result

This lists down all objects / folders in a given path. Folder_path can be left as None by default and method will list the immediate contents of the root of the bucket.

Answer 15

Here is the solution

import boto3

s3=boto3.resource('s3')
BUCKET_NAME = 'Your S3 Bucket Name'
allFiles = s3.Bucket(BUCKET_NAME).objects.all()
for file in allFiles:
    print(file.key)

Answer 16

It can also be done as follows:

csv_files = s3.list_objects_v2(s3_bucket_path)
    for obj in csv_files['Contents']:
        key = obj['Key']

Answer 17

Using cloudpathlib

cloudpathlib provides a convenience wrapper so that you can use the simple pathlib API to interact with AWS S3 (and Azure blob storage, GCS, etc.). You can install with pip install "cloudpathlib[s3]".

Like with pathlib you can use glob or iterdir to list the contents of a directory.

Here's an example with a public AWS S3 bucket that you can copy and past to run.

from cloudpathlib import CloudPath

s3_path = CloudPath("s3://ladi/Images/FEMA_CAP/2020/70349")

# list items with glob
list(
    s3_path.glob("*")
)[:3]
#> [ S3Path('s3://ladi/Images/FEMA_CAP/2020/70349/DSC_0001_5a63d42e-27c6-448a-84f1-bfc632125b8e.jpg'),
#>   S3Path('s3://ladi/Images/FEMA_CAP/2020/70349/DSC_0002_a89f1b79-786f-4dac-9dcc-609fb1a977b1.jpg'),
#>   S3Path('s3://ladi/Images/FEMA_CAP/2020/70349/DSC_0003_02c30af6-911e-4e01-8c24-7644da2b8672.jpg')]

# list items with iterdir
list(
    s3_path.iterdir()
)[:3]
#> [ S3Path('s3://ladi/Images/FEMA_CAP/2020/70349/DSC_0001_5a63d42e-27c6-448a-84f1-bfc632125b8e.jpg'),
#>   S3Path('s3://ladi/Images/FEMA_CAP/2020/70349/DSC_0002_a89f1b79-786f-4dac-9dcc-609fb1a977b1.jpg'),
#>   S3Path('s3://ladi/Images/FEMA_CAP/2020/70349/DSC_0003_02c30af6-911e-4e01-8c24-7644da2b8672.jpg')]

^{Created at 2021-05-21 20:38:47 PDT by reprexlite v0.4.2}