Generate signed build provenance attestations for workflow artifacts. Internally powered by the @actions/attest package.
Attestations bind some subject (a named artifact along with its digest) to a SLSA build provenance predicate using the in-toto format.
A verifiable signature is generated for the attestation using a short-lived Sigstore-issued signing certificate. If the repository initiating the GitHub Actions workflow is public, the public-good instance of Sigstore will be used to generate the attestation signature. If the repository is private/internal, it will use the GitHub private Sigstore instance.
Once the attestation has been created and signed, it will be uploaded to the GH attestations API and associated with the repository from which the workflow was initiated.
Attestations can be verified using the attestation command in the GitHub
CLI.
See Using artifact attestations to establish provenance for builds for more information on artifact attestations.
Within the GitHub Actions workflow which builds some artifact you would like to attest:
-
Ensure that the following permissions are set:
permissions: id-token: write attestations: write
The
id-tokenpermission gives the action the ability to mint the OIDC token necessary to request a Sigstore signing certificate. Theattestationspermission is necessary to persist the attestation. -
Add the following to your workflow after your artifact has been built:
- uses: actions/attest-build-provenance@v1 with: subject-path: '<PATH TO ARTIFACT>'
The
subject-pathparameter should identify the artifact for which you want to generate an attestation.
See action.yml
- uses: actions/attest-build-provenance@v1
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 2500).
subject-path:
# SHA256 digest of the subject for the attestation. Must be in the form
# "sha256:hex_digest" (e.g. "sha256:abc123..."). Must specify exactly one
# of "subject-path" or "subject-digest".
subject-digest:
# Subject name as it should appear in the attestation. Required unless
# "subject-path" is specified, in which case it will be inferred from the
# path.
subject-name:
# Whether to push the attestation to the image registry. Requires that the
# "subject-name" parameter specify the fully-qualified image name and that
# the "subject-digest" parameter be specified. Defaults to false.
push-to-registry:
# Whether to attach a list of generated attestations to the workflow run
# summary page. Defaults to true.
show-summary:
# The GitHub token used to make authenticated API requests. Default is
# ${{ github.token }}
github-token:| Name | Description | Example |
|---|---|---|
bundle-path |
Absolute path to the file containing the generated attestation | /tmp/attestation.jsonl |
Attestations are saved in the JSON-serialized Sigstore bundle format.
If multiple subjects are being attested at the same time, each attestation will be written to the output file on a separate line (using the JSON Lines format).
No more than 2500 subjects can be attested at the same time. Subjects will be processed in batches 50. After the initial group of 50, each subsequent batch will incur an exponentially increasing amount of delay (capped at 1 minute of delay per batch) to avoid overwhelming the attestation API.
For the basic use case, simply add the attest-build-provenance action to your
workflow and supply the path to the artifact for which you want to generate
attestation.
name: build-attest
on:
workflow_dispatch:
jobs:
build:
permissions:
id-token: write
contents: read
attestations: write
steps:
- name: Checkout
uses: actions/checkout@v4
- name: Build artifact
run: make my-app
- name: Attest
uses: actions/attest-build-provenance@v1
with:
subject-path: '${{ github.workspace }}/my-app'If you are generating multiple artifacts, you can generate a provenance
attestation for each by using a wildcard in the subject-path input.
- uses: actions/attest-build-provenance@v1
with:
subject-path: 'dist/**/my-bin-*'For supported wildcards along with behavior and documentation, see @actions/glob which is used internally to search for files.
Alternatively, you can explicitly list multiple subjects with either a comma or newline delimited list:
- uses: actions/attest-build-provenance@v1
with:
subject-path: 'dist/foo, dist/bar'- uses: actions/attest-build-provenance@v1
with:
subject-path: |
dist/foo
dist/barWhen working with container images you can invoke the action with the
subject-name and subject-digest inputs.
If you want to publish the attestation to the container registry with the
push-to-registry option, it is important that the subject-name specify the
fully-qualified image name (e.g. "ghcr.io/user/app" or
"acme.azurecr.io/user/app"). Do NOT include a tag as part of the image name --
the specific image being attested is identified by the supplied digest.
Attestation bundles are stored in the OCI registry according to the Cosign Bundle Specification.
NOTE: When pushing to Docker Hub, please use "index.docker.io" as the registry portion of the image name.
name: build-attested-image
on:
push:
branches: [main]
jobs:
build:
runs-on: ubuntu-latest
permissions:
id-token: write
packages: write
contents: read
attestations: write
env:
REGISTRY: ghcr.io
IMAGE_NAME: ${{ github.repository }}
steps:
- name: Checkout
uses: actions/checkout@v4
- name: Login to GitHub Container Registry
uses: docker/login-action@v3
with:
registry: ${{ env.REGISTRY }}
username: ${{ github.actor }}
password: ${{ secrets.GITHUB_TOKEN }}
- name: Build and push image
id: push
uses: docker/[email protected]
with:
context: .
push: true
tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
- name: Attest
uses: actions/attest-build-provenance@v1
id: attest
with:
subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
subject-digest: ${{ steps.push.outputs.digest }}
push-to-registry: true