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35 lines
1.8 KiB
Markdown
35 lines
1.8 KiB
Markdown
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# Provenance CI reference workflows
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These are copy-paste reference workflows for producing SLSA provenance with the
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Packer `provenance` post-processor. They are **not** wired into this
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repository's own CI — copy them into your project's `.github/workflows/`
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directory and adapt the template and artifact paths.
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## SLSA levels and Packer
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SLSA Build levels are mostly properties of the build **platform**, not the
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build **tool**. Packer is a tool, so its reach is:
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| SLSA Build level | Requirement | Packer's role | What Packer provides |
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|---|---|---|---|
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| **L1** | Provenance exists and is distributed | Fully in Packer | Provenance generation |
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| **L2** | Provenance signed by a hosted platform | Packer signs via CI OIDC identity | Keyless signing in CI |
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| **L3** | Hardened platform; build steps cannot reach the signing key | Platform property; Packer is compatible | Delegated-signing pattern |
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| **L4** | — | Not defined in SLSA v1.0 | — |
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Packer generates SLSA Provenance v1 and reaches Build L1, and L2 when run on a
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hosted CI with keyless signing. L3 is a property of the build platform: it
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requires the signing key to be unreachable by the build steps. Packer does not
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confer L3 on its own, but the delegated-signing pattern below is compatible with
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an L3 platform.
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## Workflows
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- [`github-actions-l2-keyless.yml`](github-actions-l2-keyless.yml) — L2: Packer
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signs provenance keyless using the workflow's OIDC identity, uploads to Rekor,
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and verifies the signed attestation with `packer verify-attestation`.
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- [`github-actions-l3-delegated.yml`](github-actions-l3-delegated.yml) —
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L3-compatible: the build job only builds and publishes a digest; provenance
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generation and signing are delegated to an isolated reusable workflow so the
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build steps cannot reach the signing material.
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