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Packer-Cn/examples/ci/github-actions-l2-keyless.yml
T
Tanmay Jain 014f8d1bbe FEAT(provenance): Add SLSA provenance attestation and verification (#13667)
* feat(provenance): add SLSA provenance and attestation signing libraries

Add internal/provenance for deriving in-toto subjects from Packer
artifacts, building SLSA Provenance v1 predicates, wrapping in-toto
statements, and best-effort git/CI source detection.

Add internal/attestation for DSSE envelope handling and a pluggable
Signer/Verifier backend supporting key (local PEM), kms (aws/gcp/
azure/hashivault), and keyless (Sigstore Fulcio) modes, plus Sigstore
bundle handling and DSSE/policy verification.

Add the supporting module dependencies in go.mod/go.sum.

* feat(provenance): add provenance post-processor

Add the opt-in "provenance" post-processor that runs after a build,
derives subjects from the artifact, emits DSSE-wrapped SLSA provenance
(and optional SBOM) attestations, signs them via the configured
signing backend, and writes sidecar files (including *.sigstore.json
bundles in keyless mode). Register it in the core post-processor set.

The provenance enable flag is a tri-state so an unset value stays
enabled through HCL2 decoding instead of being silently disabled.

* feat(provenance): add verify-attestation command

Add "packer verify-attestation" to verify signed DSSE attestations
against key, KMS, and keyless policy inputs, including optional
Sigstore bundle checks for Rekor and timestamp evidence. Register the
command in the CLI.

* docs(provenance): add reference CI workflows and changelog

Add reference GitHub Actions workflows under examples/ci for SLSA L2
keyless signing and L3-compatible delegated signing

* fix: lint and tests

* Added docs for Provenance PostProcessor
2026-07-21 13:40:42 +05:30

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YAML

# Reference workflow — NOT wired into this repository's CI.
#
# Copy this into your own project's .github/workflows/ directory.
#
# SLSA Build L2 pattern: Packer signs the provenance attestation keyless, using
# the GitHub Actions workflow's own OIDC identity (Fulcio) and records the
# signature in the Rekor transparency log. This yields signed, transparently
# logged provenance produced by a hosted platform.
#
# This does NOT confer SLSA L3 on its own: the build job can still reach the
# (ephemeral) signing material. See github-actions-l3-delegated.yml for the
# L3-compatible delegated-signing pattern.
name: build-and-sign-provenance
on:
push:
tags:
- "v*"
permissions:
contents: read
# Required so Packer's keyless signing can request an OIDC token from GitHub
# and exchange it with Fulcio for a short-lived signing certificate.
id-token: write
jobs:
build:
runs-on: ubuntu-latest
env:
# Must match the workflow's OIDC identity so verification can pin it.
KEYLESS_IDENTITY: "https://github.com/${{ github.repository }}/.github/workflows/build-and-sign-provenance.yml@${{ github.ref }}"
KEYLESS_OIDC_ISSUER: "https://token.actions.githubusercontent.com"
steps:
- name: Checkout
uses: actions/checkout@v4
- name: Install Packer
uses: hashicorp/setup-packer@main
with:
version: latest
- name: Initialize plugins
run: packer init .
# The template below is expected to declare two input variables and a
# keyless provenance post-processor. NOTE: Packer's `env()` function may
# only appear in a variable `default`, never inline in a block, so the
# workflow passes the values with `-var` instead.
#
# variable "keyless_identity" { type = string }
# variable "keyless_oidc_issuer" { type = string }
#
# post-processor "provenance" {
# signing_mode = "keyless"
# upload_tlog = true
# keyless_identity = var.keyless_identity
# keyless_oidc_issuer = var.keyless_oidc_issuer
# }
#
# Packer picks up the ambient GitHub OIDC token automatically from the
# ACTIONS_ID_TOKEN_REQUEST_URL / ACTIONS_ID_TOKEN_REQUEST_TOKEN variables
# that are available when `id-token: write` is granted above.
- name: Build and sign
run: |
packer build \
-var "keyless_identity=${KEYLESS_IDENTITY}" \
-var "keyless_oidc_issuer=${KEYLESS_OIDC_ISSUER}" \
.
# Verify the signed attestation with Rekor-backed transparency evidence
# using the generated Sigstore bundle sidecar (*.sigstore.json).
- name: Verify attestation
run: |
for att in *.provenance.json; do
packer verify-attestation \
-signing-mode=keyless \
-bundle="${att%.json}.sigstore.json" \
-require-rekor \
-require-timestamp \
-keyless-identity="${KEYLESS_IDENTITY}" \
-keyless-oidc-issuer="${KEYLESS_OIDC_ISSUER}" \
-predicate-type="https://slsa.dev/provenance/v1" \
"${att}"
done
- name: Upload provenance artifacts
uses: actions/upload-artifact@v4
with:
name: provenance
path: |
*.provenance.json
*.sigstore.json