Add attestation download API endpoint, add download_url (!212141) · Merge requests · GitLab.org / GitLab

Background

The grouppipeline security group is working towards providing users with SLSA Level 3 Provenance Attestations. Quoting from the SLSA documentation, it states that attestations are:

It’s the verifiable information about software artifacts describing where, when, and how something was produced. For higher SLSA levels and more resilient integrity guarantees, provenance requirements are stricter and need a deeper, more technical understanding of the predicate. Describe how an artifact or set of artifacts was produced so that:

Consumers of the provenance can verify that the artifact was built according to expectations.

Others can rebuild the artifact, if desired.

As a simplified TL;DR, in the context of GitLab, a provenance statement is a JSON document that correlates the SHA-256 sum of an artifact with the build information. A worker then performs a digital signature, called a provenance attestation, stored as a "Sigstore Bundle" blob. This is a highly sought-after feature, particularly for our GitLab Ultimate customers.

Why this MR?

This merge request addresses two problems identified in the "Polish the MVC end-to-end Attestation workflow" ticket:

Add a new API endpoint for retrieving the bundle. This bundle will be retrieved by glab to verify the integrity of artifacts. More information available in "Attestation verification via glab CLI".
Add two new fields to the list endpoint for attestations. iid was previously missing from the list endpoint and download_url is related to this MR.

References

How to set up and validate locally

You can create test data as below. You can also do a full end-to-end run of the ProvenanceService locally.

a = SupplyChain::Attestation.new do |a|
  a.project_id = 9
  tf = Tempfile.new
  tf.write("this is the bundle contents")

  a.file = tf
  a.predicate_kind = :provenance
  a.predicate_type = "http://example.com/predicate"
  a.subject_digest = "5db1fee4b5703808c48078a76768b155b421b210c0761cd6a5d223f4d99f1eaa"
end

a.save

http http://gdk.test:3000/api/v4/projects/root%2ftest-child-pipeline/attestations/5db1fee4b5703808c48078a76768b155b421b210c0761cd6a5d223f4d99f1eaa
HTTP/1.1 200 OK
[...]

[
    {
        "build_id": null,
        "created_at": "2025-11-12T01:02:26.254Z",
        "download_url": "http://gdk.test:3000/api/v4/projects/9/attestations/1/download",
        "expire_at": null,
        "id": 1,
        "iid": 1,
        "predicate_kind": "provenance",
        "predicate_type": "http://example.com/predicate",
        "project_id": 9,
        "status": "success",
        "subject_digest": "5db1fee4b5703808c48078a76768b155b421b210c0761cd6a5d223f4d99f1eaa",
        "updated_at": "2025-11-12T01:02:26.254Z"
    },
    {
        "build_id": null,
        "created_at": "2025-11-12T01:09:58.480Z",
        "download_url": "http://gdk.test:3000/api/v4/projects/9/attestations/5/download",
        "expire_at": null,
        "id": 6,
        "iid": 5,
        "predicate_kind": "sbom",
        "predicate_type": "http://example.com/predicate",
        "project_id": 9,
        "status": "success",
        "subject_digest": "5db1fee4b5703808c48078a76768b155b421b210c0761cd6a5d223f4d99f1eaa",
        "updated_at": "2025-11-12T21:49:51.016Z"
    }
]

http http://gdk.test:3000/api/v4/projects/9/attestations/6/download
HTTP/1.1 200 OK
Cache-Control: max-age=0, private, must-revalidate
Content-Disposition: attachment; filename=sigstore.bundle
Content-Length: 27
Content-Security-Policy: default-src 'none'
Content-Type: application/vnd.dev.sigstore.bundle.v0.3+json
Date: Mon, 17 Nov 2025 01:53:10 GMT
ETag: W/"3844ef756a75f7845a432ee27d70632a"
Nel: {"max_age": 0}
Vary: Origin
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
X-Gitlab-Meta: {"correlation_id":"01KA7R843YW7ZD48QQ1480Y28V","version":"1"}
X-Request-Id: 01KA7R843YW7ZD48QQ1480Y28V
X-Runtime: 2.260871

this is the bundle contents

The image below shows the user navigating directly to the download endpoint:

Database

https://console.postgres.ai/gitlab/gitlab-production-ci/sessions/45571/commands/139696

SELECT "slsa_attestations".* FROM "slsa_attestations" WHERE "slsa_attestations"."project_id" = 9 AND "slsa_attestations"."iid" = 6 ORDER BY "slsa_attestations"."id" ASC LIMIT 2

 Limit  (cost=0.01..0.02 rows=1 width=154) (actual time=0.032..0.032 rows=0 loops=1)
   Buffers: shared hit=3
   ->  Sort  (cost=0.01..0.02 rows=1 width=154) (actual time=0.031..0.031 rows=0 loops=1)
         Sort Key: slsa_attestations.id
         Sort Method: quicksort  Memory: 25kB
         Buffers: shared hit=3
         ->  Seq Scan on public.slsa_attestations  (cost=0.00..0.00 rows=1 width=154) (actual time=0.005..0.005 rows=0 loops=1)
               Filter: ((slsa_attestations.project_id = 9) AND (slsa_attestations.iid = 6))
               Rows Removed by Filter: 0
Settings: work_mem = '100MB', effective_cache_size = '338688MB', random_page_cost = '1.5', jit = 'off', seq_page_cost = '4'

Please note that an index exists. I don't know why the database is not using the plan, it may be that it considers the above faster than using the index.

    "index_slsa_attestations_on_project_id_iid" UNIQUE, btree (project_id, iid)

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #578751 (closed)

Edited Nov 17, 2025 by Sam Roque-Worcel

Add attestation download API endpoint, add download_url