ci: pin release pipeline actions (Closes #1378)

.gitea/workflows/ci.yml

@@ -7,12 +7,15 @@ on:
     branches: [main]
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
         with: { python-version: "3.11" }
       - run: pip install -r requirements.txt
       - run: pip install -r requirements-audit.txt
@@ -23,7 +26,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: lint
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Build deterministic release bundle
         run: |
           SOURCE_DATE_EPOCH="$(git show -s --format=%ct "$GITHUB_SHA")"
@@ -33,7 +36,7 @@ jobs:
             --commit "$GITHUB_SHA" \
             --source-date-epoch "$SOURCE_DATE_EPOCH"
       - name: Upload tested release bundle
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@a8a3f3ad30e3422c9c7b888a15615d19a852ae32 # v3.1.3
         with:
           name: release-bundle
           path: dist/
@@ -44,11 +47,11 @@ jobs:
     env:
       STACKCHAIN_RUN_RELEASE_E2E: "1"
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
         with: { python-version: "3.11" }
       - name: Download assembled release bundle
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@9bc31d5ccc31df68ecc42ccf4149144866c47d8a # v3.0.2
         with:
           name: release-bundle
           path: dist
@@ -66,9 +69,9 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Download tested release bundle
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@9bc31d5ccc31df68ecc42ccf4149144866c47d8a # v3.0.2
         with:
           name: release-bundle
           path: dist

tests/test_ci_workflow.py

@@ -1,13 +1,44 @@
 from pathlib import Path
+import re
 
 
 WORKFLOW = Path(".gitea/workflows/ci.yml")
+ACTION_REFERENCE = re.compile(
+    r"^\s*- uses: (?P<action>[^\s@]+)@(?P<revision>[^\s#]+)\s+# (?P<version>v\d+(?:\.\d+){1,2})$",
+    re.MULTILINE,
+)
+DOWNLOAD_ARTIFACT = (
+    "actions/download-artifact@9bc31d5ccc31df68ecc42ccf4149144866c47d8a # v3.0.2"
+)
 
 
 def test_ci_uses_gitea_compatible_artifact_action():
     text = WORKFLOW.read_text()
     assert "actions/upload-artifact@v4" not in text
-    assert "actions/upload-artifact@v3" in text
+    assert re.search(
+        r"actions/upload-artifact@[0-9a-f]{40}\s+# v3\.\d+\.\d+", text
+    )
+
+
+def test_ci_pins_every_external_action_to_a_reviewable_commit():
+    text = WORKFLOW.read_text()
+    uses_lines = [line for line in text.splitlines() if line.lstrip().startswith("- uses:")]
+    references = list(ACTION_REFERENCE.finditer(text))
+
+    assert len(references) == len(uses_lines)
+    assert references
+    for reference in references:
+        assert re.fullmatch(r"[0-9a-f]{40}", reference["revision"])
+
+
+def test_ci_grants_repository_write_access_only_to_release_job():
+    text = WORKFLOW.read_text()
+    jobs = text[text.index("jobs:") :]
+    before_release, release = jobs.split("  release-candidate:", 1)
+
+    assert "permissions:\n  contents: read" in text[: text.index("jobs:")]
+    assert "contents: write" not in before_release
+    assert "permissions:\n      contents: write" in release
 
 
 def test_ci_installs_declared_requirements_before_tests():
@@ -40,7 +71,7 @@ def test_release_promotion_waits_for_tests_and_bundle():
 
     assert "needs: [lint, build-release, browser-journey]" in release
     assert "github.event_name == 'push'" in release
-    assert "actions/download-artifact@v3" in release
+    assert DOWNLOAD_ARTIFACT in release
     assert (
         'python3 scripts/verify_release.py --input-dir dist --commit "$TARGET" --repository .'
         in release
@@ -54,7 +85,7 @@ def test_release_promotion_waits_for_every_packaged_mobile_journey():
     release = text[text.index("  release-candidate:") :]
 
     assert "needs: build-release" in browser
-    assert "actions/download-artifact@v3" in browser
+    assert DOWNLOAD_ARTIFACT in browser
     assert "pip install -r requirements-e2e.txt" in browser
     assert "python3 -m playwright install --with-deps chromium" in browser
     assert 'STACKCHAIN_RUN_RELEASE_E2E: "1"' in browser