Is it possible for anonymous user to get object metadata (etag) without "full request"?

Question

I am setting object with public-read-write ACL with following code:

o = s3.Object(bucket, key)
o.Acl().put(ACL='public-read-write')

I can now access object on https://hostname/tenant:bucket/key publicly.

I can get ETAG with anonymous user if I do full request (meaning it downloads the file).

Is it possible for anonymous user to get object metadata (etag) without doing full download of the file?

Is it possible to get metadata (ETAG) without

Answer 1

Maybe use "head_object" if you are using boto to get metadata of the key.

s3 = boto3.client('s3')

response = s3.head_object(Bucket=bucket_name, Key=file_name)

Answer 2

You can retrieve the ETag for a public object using clients like s3cmd. You can achieve this by running the following command:

s3cmd info s3://bucket/key

The result will typically include information such as:

• File size: 10180
• Last modification: Wed, 20 Sep 2023 09:40:28 GMT
• MIME type: text/html
• Storage: STANDARD
• MD5 sum: 55aea36e6318f3ff30cf696495fd84ed-1
• SSE (Server-Side Encryption): none
• Policy: Not available: GetPolicy permission is needed to read the policy

The MD5 sum, also known as the ETag, in this context, represents the object's Entity Tag. You can obtain this information without having to download the entire object. Third-party tools like s3cmd are capable of retrieving object metadata, as demonstrated in the example above.