Jenna's Runbooks

AWS S3 Object Finder | Boto3 Script

Photo by Francesco Ungaro on Unsplash

AWS S3 Object Finder | Boto3 Script

Jenna's Runbooks's photo
Jenna's Runbooks
·

8 min read

Table of contents

Overview

🔎 Quickly find AWS S3 Objects inside buckets hosting huge volumes of files using my latest Boto3 script! You can easily locate specific objects in your AWS profile by providing a few command line arguments. By specifying the AWS profile, bucket name, object name, and optional prefix you can efficiently search for objects and obtain a list of matching keys, allowing you to pinpoint the location of a particular file.

This 📜 performs the following tasks:

✔️ Handle pagination when dealing with large buckets containing thousands of objects

✔️ Perform a recursive search for an object in an S3 bucket, considering the object's name and optional prefix

✔️ Display the keys of matching objects found in the bucket

✔️ List all buckets in a specified AWS profile

✔️ List top-level prefixes in a specified bucket

Purpose

This AWS S3 Object Finder script is particularly helpful when troubleshooting upload error logs especially when dealing with buckets that host thousands of objects and extensive prefixes. In these scenarios, manually searching for objects can be very time-consuming. By utilizing the script's pagination and object prefix features, you can significantly speed up the search process and narrow down the results to the desired subset of objects. This saves both time and effort allowing you to efficiently troubleshoot specific object data without having to search for objects manually.

Script Functionality

Link to the script: https://github.com/jksprattler/aws-tools/blob/main/scripts/aws_s3_object_finder.py

Usage

Here's a look at the options available from the -h/--help output:

❯ python aws_s3_object_finder.py --help
usage: aws_s3_object_finder.py [-h] -p PROFILE [-b BUCKET] [-o OBJECT] [-x PREFIX] {list-buckets,list-prefixes} ...

Search for an object in an S3 bucket.

positional arguments:
  {list-buckets,list-prefixes}
                        Additional commands
    list-buckets        List buckets in profile, use after -p
    list-prefixes       List top-level prefixes in bucket, use after -p and -b

optional arguments:
  -h, --help            show this help message and exit
  -p PROFILE, --profile PROFILE
                        AWS profile name
  -b BUCKET, --bucket BUCKET
                        S3 bucket name
  -o OBJECT, --object OBJECT
                        Object name to search for
  -x PREFIX, --prefix PREFIX
                        Object prefix for high volume bucket search

Here's an example of listing all buckets in a specified AWS profile:

❯ python aws_s3_object_finder.py -p cloud-sandbox list
sandbox-cloudtrail
sandbox-trail-bucket
lstest2022

Here's an example of listing all top-level prefixes in a specified bucket:

❯ python aws_s3_object_finder.py -p default -b jennasprattler.com list-prefixes
assets/
images/

Here's an example of listing all S3 objects in a specified bucket by calling a keyword in the prefix as the object:

❯ python aws_s3_object_finder.py -p cloud-sandbox -b sandbox-cloudtrail -o us-west-2
'us-west-2' found in bucket 'sandbox-cloudtrail'
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_1bxLMBY0uRL1X67x.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_HzrxfJgKaRrQr2d3.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_Uyg59kXzzIB0y2YS.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_rzKX1qISHRXL6aru.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2105Z_GlZuUn6pUrCDzbhr.json.gz
### Redacted for brevity

Here's an example of listing all objects in a bucket under a specific prefix where there are 1,000s of objects requiring pagination. If you don't know the specific file/object name then you can define the closest matching prefix anywhere in the key as the object argument followed by the initial prefix of the key as the prefix argument:

❯ python aws_s3_object_finder.py -p cloud-sandbox -b sandbox-cloudtrail -o us-west-2 -x AWSLogs/
'us-west-2' found in bucket 'sandbox-cloudtrail'
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_1bxLMBY0uRL1X67x.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_HzrxfJgKaRrQr2d3.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_Uyg59kXzzIB0y2YS.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_rzKX1qISHRXL6aru.json.gz
### Redacted for brevity

In some cases, you will need to be more granular with how you specify objects and prefixes based on your prefix structure. In other words, you could have duplicate or overlapping prefix names causing a search to fail. The solution for this is to specify additional values in your delimiter-separated values for '/' for the prefix argument:

❯ python aws_s3_object_finder.py -p cloud-sandbox -b sandbox-cloudtrail -o us-west-2 -x AWSLogs/accountId/CloudTrail/
'us-west-2' found in bucket 'sandbox-cloudtrail'
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_1bxLMBY0uRL1X67x.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_HzrxfJgKaRrQr2d3.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_Uyg59kXzzIB0y2YS.json.gz
Key(s) matching 'us-west-2': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_rzKX1qISHRXL6aru.json.gz
### Redacted for brevity

Here's an example of finding a specific object/filename in a bucket hosting thousands of objects by specifying a prefix with the object argument:

❯ python aws_s3_object_finder.py -p cloud-sandbox -b sandbox-cloudtrail -o accountId_CloudTrail_us-west-2_20220120T2100Z_1bxLMBY0uRL1X67x.json.gz -x AWSLogs/
'accountId_CloudTrail_us-west-2_20220120T2100Z_1bxLMBY0uRL1X67x.json.gz' found in bucket 'sandbox-cloudtrail'
Key(s) matching 'accountId_CloudTrail_us-west-2_20220120T2100Z_1bxLMBY0uRL1X67x.json.gz': sandbox-cloudtrail/AWSLogs/accountId/CloudTrail/us-west-2/2022/01/20/accountId_CloudTrail_us-west-2_20220120T2100Z_1bxLMBY0uRL1X67x.json.gz

Code Explanation

Inside the main function, the args are set to the parse_args() function. If no arguments are provided the script outputs the usage from the parser and exits. The next conditional will run the list_buckets function if the list-buckets argument is provided with a profile. Next, it will run the list_prefixes function if the list-prefixes argument is provided with a profile and bucket. Finally, the search_s3_object function is run when at least the profile, bucket and object are provided - the prefix is optional.

def main():
    """ Parse args and call either S3 bucket list or object search function """
    args = parse_args()

    if not args:
        return

    if args.command == 'list-buckets':
        list_buckets(args.profile)
    elif args.command == 'list-prefixes':
        list_prefixes(args.profile, args.bucket)
    else:
        search_s3_object(args.profile, args.bucket, args.object, args.prefix)

if __name__ == "__main__":
    main()

Below is the parse_arguments() function. This is self-explanatory by reviewing the help comments for each of the arguments. Also, see usage in the output example above.

def parse_args():
    """ Define cli args to be parsed into main() """
    parser = argparse.ArgumentParser(description='Search for an object in an S3 bucket.')
    parser.add_argument('-p', '--profile', required=True, help='AWS profile name')
    parser.add_argument('-b', '--bucket', help='S3 bucket name')
    parser.add_argument('-o', '--object', help='Object name to search for')
    parser.add_argument('-x', '--prefix', help='Object prefix for high volume bucket search')
    subparser = parser.add_subparsers(dest='command', help='Additional commands')
    subparser.add_parser('list-buckets',
                         help='List buckets in profile, use after -p')
    subparser.add_parser('list-prefixes', help='List top-level prefixes in bucket,\
                                                use after -p and -b')
    args = parser.parse_args()

    if args.command == 'list-buckets':
        return args

    if args.command == 'list-prefixes' and args.bucket:
        return args

    if not args.bucket or (not args.bucket and not args.command == 'list-prefixes') \
        or not args.object:
        parser.print_usage()
        return None

    return args

If the user provides the list-buckets argument then the list_buckets(profile_name) function is called and provides the output of all buckets in the specified AWS profile. It creates a session using the provided profile name, establishes an S3 client using the session, and sends a request to list the buckets associated with the profile.

def list_buckets(profile_name):
    """ List buckets in specified profile """
    session = boto3.Session(profile_name=profile_name)
    s3_client = session.client('s3')
    buckets = s3_client.list_buckets()['Buckets']

    for bucket in buckets:
        print(bucket['Name'])

If the user provides the list-prefixes argument then the list_prefixes(profile_name, bucket_name) function is called and provides the output of all top-level prefixes within the specified bucket.

def list_prefixes(profile_name, bucket_name):
    """ List top-level prefixes in a specified bucket """
    session = boto3.Session(profile_name=profile_name)
    s3_client = session.client('s3')
    paginator = s3_client.get_paginator('list_objects_v2')
    list_objects_args = {'Bucket': bucket_name, 'Delimiter': '/'}
    page_iterator = paginator.paginate(**list_objects_args)

    prefixes = []
    for page in page_iterator:
        if 'CommonPrefixes' in page:
            # Iterate over the CommonPrefixes list and extract top-level prefixes
            prefixes.extend([prefix['Prefix'] for prefix in page['CommonPrefixes']])

    if prefixes:
        for prefix in prefixes:
            print(prefix)
    else:
        print(f"No top-level prefixes found in bucket '{bucket_name}'")

Excluding any of the "list*" arguments, when the user provides the --object and/or --prefix argument with the AWS profile then the search_s3_object(profile_name, bucket_name, object_name, object_prefix) function is called. It creates a session using the specified profile name, creates an S3 client using the session, and sends a request to list the objects in the specified bucket. The response is then processed, filtering the objects based on the provided object name and object prefix. If any matching objects are found, their keys are printed to the console, indicating their location within the bucket. If no matching objects are found, a message is printed to indicate that the object was not found in the bucket.

def search_s3_object(profile_name, bucket_name, object_name, object_prefix):
    """
    Create a session using the specified profile
    Create s3 client using the session
    Perform recursive search using pagination for the S3 bucket object
    Use optional prefix when dealing w/ high volume objects
    """
    session = boto3.Session(profile_name=profile_name)
    s3_client = session.client('s3')
    paginator = s3_client.get_paginator('list_objects_v2')
    list_objects_args = {'Bucket': bucket_name}

    if object_prefix:
        list_objects_ars['Prefix'] = object_prefix

    page_iterator = paginator.paginate(**list_objects_args)

    for page in page_iterator:
        if 'Contents' in page:
            # Check if the object name is in the retrieved keys
            objects = [obj['Key'] for obj in page['Contents'] if object_name in obj['Key']]

            if objects:
                print(f"'{object_name}' found in bucket '{bucket_name}'")
                for obj in objects:
                    print(f"Key(s) matching '{object_name}': {bucket_name}/{obj}")
                return

    print(f"'{object_name}' not found in bucket '{bucket_name}'")

A few items to highlight from the search_s3_object() function:

  • list_objects_args = {'Bucket': bucket_name}: This line creates a dictionary called list_objects_args with a key-value pair. The key is 'Bucket', and the value is the bucket_name variable. This dictionary is used to specify the bucket name when calling the list_objects_v2 API.

  • if object_prefix: list_objects_args['Prefix'] = object_prefix: This conditional statement checks if the object_prefix variable has a value. If object_prefix is not empty or None, it means a prefix was provided. In that case, it adds another key-value pair to the list_objects_args dictionary. The key is 'Prefix', and the value is the object_prefix variable. This prefix specifies a filter to narrow down the objects returned by the API call.

  • page_iterator = paginator.paginate(**list_objects_args): This line creates a page_iterator object using the paginator.paginate() method. The double asterisks ** before list_objects_args unpacks the dictionary into keyword arguments. This means that the paginator.paginate() method receives the dictionary key-value pairs as separate arguments. In this case, it passes the 'Bucket' and 'Prefix' arguments to the paginator.paginate() method.

  • These provide the necessary arguments for the paginator.paginate() method based on the provided bucket name and optional object prefix. It allows you to paginate through the S3 bucket objects, retrieving a subset of objects at a time, based on the provided arguments while still offering flexibility in that the --prefix argument is not required to run the script although it will still be needed if your bucket consists of thousands of objects.

Conclusion

This approach to searching for S3 bucket objects provides quick troubleshooting capability and enables you to locate data with ease. Whether you need to identify a precise object location or navigate through large buckets with complex prefixes, this AWS Object Finder script can be a helpful tool when working with AWS S3!

Boto3 Resources

AWSPythonCloudCloud ComputingS3