fix(blackhole sink): implement end-to-end acknowledgements

[sanjams2]

Summary

Addresses #24281

The blackhole sink was consuming events without updating finalizer status, causing sources that depend on acknowledgements (like aws_s3 with SQS) to never receive delivery confirmation. This resulted in SQS messages never being deleted and queue depth growing indefinitely.

Added proper finalizer handling by taking finalizers from events and marking them as delivered after processing, matching the pattern used by other sinks like console.

Vector configuration

  sources:
    s3_source:
      type: aws_s3
      sqs:
        queue_url: "https://sqs.us-east-2.amazonaws.com/xxx/my-queue"

  sinks:
    blackhole:
      type: blackhole
      inputs: [s3_source]
      acknowledgements:
        enabled: true

How did you test this PR?

make test

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

• Closes: blackhole sink does not implement end-to-end acknowledgements despite documentation claiming support #24281

Notes

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[github-actions]

All contributors have signed the CLA ✍️ ✅
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[sanjams2]

I have read the CLA Document and I hereby sign the CLA

[sanjams2]

recheck

[sanjams2]

recheck

[Mr-iX]

When could this be merged and a new version released? We're also affected by this issue and would hope for a fix soon.

[thomasqueirozb]

Nice, thanks for this! Once merged we can also remove run_and_assert_nonsending_sink_compliance. I'll follow up in a separate PR

[thomasqueirozb]

@Mr-iX Vector adheres to the release schedule tracked by https://calendar.vector.dev. In the meantime, you could always use nightlies (once this is merged).