build: adding provenance generation to release-please workflow (#256)

**Requirements**

- [ ] I have added test coverage for new or changed functionality
- [ ] I have followed the repository's [pull request submission
guidelines](../blob/main/CONTRIBUTING.md#submitting-pull-requests)
- [ ] I have validated my changes against all supported platform
versions

**Related issues**

Provide links to any issues in this repository or elsewhere relating to
this pull request.

**Describe the solution you've provided**

Using Github SLSA generator to generate build provenance for
`python-server-sdk`

Implementation based off of previous SDK SLSA integrations with
release-please and Python-specific guidance here:
https://sethmlarson.dev/python-and-slsa#generating-a-provenance-attestation

**Describe alternatives you've considered**

Provide a clear and concise description of any alternative solutions or
features you've considered.

**Additional context**

Add any other context about the pull request here.

.github/actions/build/action.yml

@@ -1,9 +1,19 @@
 name: Build distribution files
 description: 'Build distribution files'
+outputs:
+  package-hashes:
+    description: "base64-encoded sha256 hashes of distribution files"
+    value: ${{ steps.package-hashes.outputs.package-hashes }}
 
 runs:
   using: composite
   steps:
     - name: Build distribution files
       shell: bash
       run: poetry build
+    - name: Hash build files for provenance 
+      id: package-hashes
+      shell: bash 
+      working-directory: ./dist
+      run: |
+        echo "package-hashes=$(sha256sum * | base64 -w0)" >> "$GITHUB_OUTPUT"

.github/workflows/manual-publish.yml

@@ -14,6 +14,8 @@ jobs:
     permissions:
       id-token: write
       contents: read
+    outputs:
+      package-hashes: ${{ steps.build.outputs.package-hashes}}
     steps:
       - uses: actions/checkout@v4
 
@@ -31,8 +33,21 @@ jobs:
           ssm_parameter_pairs: '/production/common/releasing/pypi/token = PYPI_AUTH_TOKEN'
 
       - uses: ./.github/actions/build
+        id: build
 
       - uses: ./.github/actions/publish
         with:
           token: ${{env.PYPI_AUTH_TOKEN}}
           dry_run: ${{ inputs.dry_run }}
+
+  release-provenance:
+    needs: [ 'build-publish' ]
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      id-token: write
+      contents: write
+    uses: slsa-framework/slsa-github-generator/.github/workflows/[email protected]
+    with:
+      base64-subjects: "${{ needs.build-publish.outputs.package-hashes }}"
+      upload-assets: ${{ !inputs.dry_run }}

.github/workflows/release-please.yml

@@ -11,6 +11,10 @@ jobs:
       id-token: write # Needed if using OIDC to get release secrets.
       contents: write # Contents and pull-requests are for release-please to make releases.
       pull-requests: write
+    outputs:
+      release-created: ${{ steps.release.outputs.release_created }}
+      upload-tag-name: ${{ steps.release.outputs.tag_name }}
+      package-hashes: ${{ steps.build.outputs.package-hashes}}
     steps:
       - uses: google-github-actions/release-please-action@v3
         id: release
@@ -41,6 +45,7 @@ jobs:
           ssm_parameter_pairs: '/production/common/releasing/pypi/token = PYPI_AUTH_TOKEN'
 
       - uses: ./.github/actions/build
+        id: build
         if: ${{ steps.release.outputs.releases_created }}
 
       - uses: ./.github/actions/build-docs
@@ -51,3 +56,17 @@ jobs:
         with:
           token: ${{env.PYPI_AUTH_TOKEN}}
           dry_run: false
+
+  release-provenance:
+    needs: [ 'release-package' ]
+    if: ${{ needs.release-package.outputs.release-created }}
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      id-token: write
+      contents: write
+    uses: slsa-framework/slsa-github-generator/.github/workflows/[email protected]
+    with:
+      base64-subjects: "${{ needs.release-package.outputs.package-hashes }}"
+      upload-assets: true
+      upload-tag-name: ${{ needs.release-package.outputs.upload-tag-name }}

PROVENANCE.md

@@ -0,0 +1,26 @@
+## Verifying SDK build provenance with the SLSA framework
+
+LaunchDarkly uses the [SLSA framework](https://slsa.dev/spec/v1.0/about) (Supply-chain Levels for Software Artifacts) to help developers make their supply chain more secure by ensuring the authenticity and build integrity of our published SDK packages.
+
+As part of [SLSA requirements for level 3 compliance](https://slsa.dev/spec/v1.0/requirements), LaunchDarkly publishes provenance about our SDK package builds using [GitHub's generic SLSA3 provenance generator](https://github.com/slsa-framework/slsa-github-generator/blob/main/internal/builders/generic/README.md#generation-of-slsa3-provenance-for-arbitrary-projects) for distribution alongside our packages. These attestations are available for download from the GitHub release page for the release version under Assets > `multiple-provenance.intoto.jsonl`.
+
+To verify SLSA provenance attestations, we recommend using [slsa-verifier](https://github.com/slsa-framework/slsa-verifier). Example usage for verifying SDK packages is included below:
+
+```
+# Download packages from PyPi
+$ pip download --only-binary=:all: launchdarkly-server-sdk
+
+# Download provenance from Github release
+$ curl --location -O \
+  https://github.com/launchdarkly/python-server-sdk/releases/download/VERSION/multiple.intoto.jsonl
+
+# Run slsa-verifier to verify provenance against package artifacts 
+$ slsa-verifier verify-artifact \
+--provenance-path multiple-provenance.intoto.jsonl \
+--source-uri github.com/launchdarkly/python-server-sdk \
+launchdarkly_server_sdk-VERSION-py3-none-any.whl
+```
+
+Alternatively, to verify the provenance manually, the SLSA framework specifies [recommendations for verifying build artifacts](https://slsa.dev/spec/v1.0/verifying-artifacts) in their documentation.
+
+**Note:** These instructions do not apply when building our SDKs from source. 

README.md

@@ -34,6 +34,10 @@ We run integration tests for all our SDKs using a centralized test harness. This
 
 We encourage pull requests and other contributions from the community. Check out our [contributing guidelines](CONTRIBUTING.md) for instructions on how to contribute to this SDK.
 
+## Verifying SDK build provenance with the SLSA framework
+
+LaunchDarkly uses the [SLSA framework](https://slsa.dev/spec/v1.0/about) (Supply-chain Levels for Software Artifacts) to help developers make their supply chain more secure by ensuring the authenticity and build integrity of our published SDK packages. To learn more, see the [provenance guide](PROVENANCE.md). 
+
 ## About LaunchDarkly
 
 * LaunchDarkly is a continuous delivery platform that provides feature flags as a service and allows developers to iterate quickly and safely. We allow you to easily flag your features and manage them from the LaunchDarkly dashboard.  With LaunchDarkly, you can: