S3: Disabling checksum validation no longer works

[oneiros]

Describe the bug

d1bc5b0 introduced a way to disable checksum validation. The current API documentation still mentions this and there are a few tests for this.

The original commit made sure that checksum_mode was only passed along when it was not DISABLED. This, I believe, is the correct behavior, because the only allowed value for the x-amz-checksum-mode header, according to https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObject.html is ENABLED.

This code was removed in df86be6 without any reason given. And indeed now when you set checksum_mode to DISABLED this gets passed down and results in an x-amz-checksum-mode header with the invalid value DISABLED.

This breaks download from S3-compatible service that reject invalid headers.

It would be amazing if the previous behavior could be reinstated in some way.

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

No header of the form

x-amz-checksum-mode: DISABLED

should be emitted.

Current Behavior

A header of the form

x-amz-checksum-mode: DISABLED

is being emitted.

Reproduction Steps

Download a file with Aws::S3::Object#download_file (or using Aws::S3::FileDownloader#download directly) and pass the option checksum_mode: 'DISABLED'.

Possible Solution

No response

Additional Information/Context

No response

Gem name ('aws-sdk', 'aws-sdk-resources' or service gems like 'aws-sdk-s3') and its version

aws-sdk-s3

Environment details (Version of Ruby, OS environment)

ruby-3.4.7
aws-sdk-core (3.236.0)
aws-sdk-s3 (1.203.0)

[jterapin]

Sorry about this. We'll take a look and follow up. Could you also provide the gem versions for aws-sdk-core and
aws-sdk-s3?

[oneiros]

Could you also provide the gem versions for aws-sdk-core and aws-sdk-s3?

Sure. Added them to the "Environment details" above.

[jterapin]

Thanks! I think I figured out what is happening but for now -

I'm not sure how you initialize the S3 client, but could you pass response_checksum_validation: 'when_required'
at the client level and avoid passing checksum_mode: "DISABLED" in the :download_file method? This will
disable the response checksum validation.

Regarding supporting this in a backwards compatible way, I'm discussing options with the team.

[oneiros]

Thank you so much. I think #3318 should fix this.

I just have one more question though: Since you deprecated the parameter, what is your deprecation policy? I.e. when will this be removed officially?

We currently have a way to set this in Mastodon and it would be great to know how urgently we need to come up with an alternative.

[jterapin]

Great! At this time, I would say that we will most likely remove this in the next Major version (v4). Feel free to re-open this issue if you have any questions.

[github-actions]

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