check if a key exists in a bucket in s3 using boto3

Question

I would like to know if a key exists in boto3. I can loop the bucket contents and check the key if it matches.

But that seems longer and an overkill. Boto3 official

Answer 1

For boto3, ObjectSummary can be used to check if an object exists.

Contains the summary of an object stored in an Amazon S3 bucket. This object doesn't contain contain the object's full metadata or any of its contents

import boto3
from botocore.errorfactory import ClientError
def path_exists(path, bucket_name):
    """Check to see if an object exists on S3"""
    s3 = boto3.resource('s3')
    try:
        s3.ObjectSummary(bucket_name=bucket_name, key=path).load()
    except ClientError as e:
        if e.response['Error']['Code'] == "404":
            return False
        else:
            raise e
    return True

path_exists('path/to/file.html')

In ObjectSummary.load

Calls s3.Client.head_object to update the attributes of the ObjectSummary resource.

This shows that you can use ObjectSummary instead of Object if you are planning on not using get(). The load() function does not retrieve the object it only obtains the summary.