Revert "bump actions/attest to v2.0.0 (actions#321)"

This reverts commit 619dbb2.

README.md

@@ -62,7 +62,7 @@ See [action.yml](action.yml)
   with:
     # Path to the artifact serving as the subject of the attestation. Must
     # specify exactly one of "subject-path" or "subject-digest". May contain a
-    # glob pattern or list of paths (total subject count cannot exceed 1024).
+    # glob pattern or list of paths (total subject count cannot exceed 2500).
     subject-path:
 
     # SHA256 digest of the subject for the attestation. Must be in the form
@@ -93,22 +93,26 @@ See [action.yml](action.yml)
 
 <!-- markdownlint-disable MD013 -->
 
-| Name          | Description                                                    | Example                 |
-| ------------- | -------------------------------------------------------------- | ----------------------- |
-| `bundle-path` | Absolute path to the file containing the generated attestation | `/tmp/attestation.json` |
+| Name          | Description                                                    | Example                  |
+| ------------- | -------------------------------------------------------------- | ------------------------ |
+| `bundle-path` | Absolute path to the file containing the generated attestation | `/tmp/attestation.jsonl` |
 
 <!-- markdownlint-enable MD013 -->
 
 Attestations are saved in the JSON-serialized [Sigstore bundle][6] format.
 
-If multiple subjects are being attested at the same time, a single attestation
-will be created with references to each of the supplied subjects.
+If multiple subjects are being attested at the same time, each attestation will
+be written to the output file on a separate line (using the [JSON Lines][7]
+format).
 
 ## Attestation Limits
 
 ### Subject Limits
 
-No more than 1024 subjects can be attested at the same time.
+No more than 2500 subjects can be attested at the same time. Subjects will be
+processed in batches 50. After the initial group of 50, each subsequent batch
+will incur an exponentially increasing amount of delay (capped at 1 minute of
+delay per batch) to avoid overwhelming the attestation API.
 
 ## Examples
 
@@ -144,8 +148,8 @@ jobs:
 
 ### Identify Multiple Subjects
 
-If you are generating multiple artifacts, you can attest all of them at the same
-time by using a wildcard in the `subject-path` input.
+If you are generating multiple artifacts, you can generate a provenance
+attestation for each by using a wildcard in the `subject-path` input.
 
 ```yaml
 - uses: actions/attest-build-provenance@v1
@@ -241,6 +245,7 @@ jobs:
 [5]: https://cli.github.com/manual/gh_attestation_verify
 [6]:
   https://github.com/sigstore/protobuf-specs/blob/main/protos/sigstore_bundle.proto
+[7]: https://jsonlines.org/
 [8]: https://github.com/actions/toolkit/tree/main/packages/glob#patterns
 [9]:
   https://docs.github.com/en/actions/security-guides/using-artifact-attestations-to-establish-provenance-for-builds

action.yml

@@ -10,7 +10,7 @@ inputs:
     description: >
       Path to the artifact serving as the subject of the attestation. Must
       specify exactly one of "subject-path" or "subject-digest". May contain a
-      glob pattern or list of paths (total subject count cannot exceed 1024).
+      glob pattern or list of paths (total subject count cannot exceed 2500).
     required: false
   subject-digest:
     description: >
@@ -44,15 +44,15 @@ inputs:
 
 outputs:
   bundle-path:
-    description: 'The path to the file containing the attestation bundle.'
+    description: 'The path to the file containing the attestation bundle(s).'
     value: ${{ steps.attest.outputs.bundle-path }}
 
 runs:
   using: 'composite'
   steps:
     - uses: actions/attest-build-provenance/predicate@36fa7d009e22618ca7cd599486979b8150596c74 # [email protected]
       id: generate-build-provenance-predicate
-    - uses: actions/attest@v2.0.0
+    - uses: actions/attest@67422f5511b7ff725f4dbd6fb9bd2cd925c65a8d # v1.4.1
       id: attest
       with:
         subject-path: ${{ inputs.subject-path }}