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 docs explicitly state how to do this.

Maybe I am missing the obvious. Can anybody point to me how I can achieve this?

Answer 1

You can do this:

import boto3

import botocore

s3 = boto3.resource('s3')

try:

    s3.Object('my-bucket', 'dootdoot.jpg').load()

except botocore.exceptions.ClientError as e:

    if e.response['Error']['Code'] == "404":

        # The object does not exist.

        ...

    else:

        # Something else has gone wrong.

        raise

else:

    # The object does exist.

    ...

A HEAD request for a single key is done by load(), this is fast even though there is a big object or there are many objects in your bucket.

If you are checking if the object exists so that you can use it, then you just do a get() or download_file() directly instead of load().

You will find out more about the Amazon S3 on AWS S3.