ci: create a stable source archive attached to the release

.github/workflows/create_archive.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+
+set -o errexit -o nounset -o pipefail
+
+JSONNET_VERSION="$(grep -Ee '^\s*const\s+version\s*=\s*"[^"]+"\s*$' vm.go | sed -E -e 's/[^"]+"([^"]+)".*/\1/')"
+
+# GITHUB_REF is set by GH actions, see
+# https://docs.github.com/en/actions/learn-github-actions/environment-variables#default-environment-variables
+
+VERSION_SUFFIX=
+if [[ ( "${GITHUB_REF_TYPE}" != 'branch' || "${GITHUB_REF_NAME}" != "prepare-release" ) &&
+      ( "${GITHUB_REF_TYPE}" != 'tag' || "${GITHUB_REF_NAME}" != "${JSONNET_VERSION}" ) ]]; then
+    >&2 echo 'WARNING: Jsonnet library version in header does not match release ref. Adding commit suffix.'
+    VERSION_SUFFIX="-${GITHUB_SHA:0:9}"
+fi
+
+# A prefix is added to better match the GitHub generated archives.
+PREFIX="go-jsonnet-${JSONNET_VERSION}${VERSION_SUFFIX}"
+ARCHIVE="go-jsonnet-${JSONNET_VERSION}${VERSION_SUFFIX}.tar.gz"
+git archive --format=tar --prefix="${PREFIX}"/ "${GITHUB_SHA}" | gzip > "$ARCHIVE"
+ARCHIVE_SHA=$(shasum -a 256 "$ARCHIVE" | awk '{print $1}')
+
+echo "archive_sha256=${ARCHIVE_SHA}" >> "$GITHUB_OUTPUT"
+echo "go_jsonnet_version=${JSONNET_VERSION}" >> "$GITHUB_OUTPUT"
+echo "go_jsonnet_version_permanent=${JSONNET_VERSION}${VERSION_SUFFIX}" >> "$GITHUB_OUTPUT"

.github/workflows/release.yml

@@ -38,3 +38,23 @@ jobs:
         with:
           version: latest
           args: release --clean --draft
+
+  create_source_archive:
+    permissions:
+      contents: write
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Create release archive
+        id: create_archive
+        run: .github/workflows/create_archive.sh
+      - name: Release
+        uses: softprops/action-gh-release@c95fe1489396fe8a9eb87c0abf8aa5b2ef267fda # v2.2.1
+        with:
+          name: ${{ steps.create_archive.outputs.go_jsonnet_version }}
+          tag_name: ${{ steps.create_archive.outputs.go_jsonnet_version }}
+          prerelease: ${{ inputs.prerelease }}
+          draft: true
+          fail_on_unmatched_files: true
+          files: go-jsonnet-*.tar.gz