workflows,release: Upload the vendored cargo code

As part of the release, let's also upload a tarball with the vendored
cargo code.  By doing this we allow distros, which usually don't have
access to the internet while performing the builds, to just add the
vendored code as a second source, making the life of the downstream
maintainers slightly easier*.

Fixes: #1203

*: The current workflow requires the downstream maintainer to download
the tarball, unpack it, run `cargo vendor`, create the tarball, etc.
Although this doesn't look like a ridiculous amount of work, it's better
if we can have it in an automated fashion.

Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>

.github/workflows/release.yaml

@@ -127,3 +127,21 @@ jobs:
           pushd $GITHUB_WORKSPACE
           echo "uploading asset '${tarball}' for tag: ${tag}"
           GITHUB_TOKEN=${{ secrets.GIT_UPLOAD_TOKEN }} hub release edit -m "" -a "${tarball}" "${tag}"
+          popd
+
+  upload-cargo-vendored-tarball:
+    needs: upload-static-tarball
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: generate-and-upload-tarball
+        run: |
+          pushd $GITHUB_WORKSPACE/src/agent
+          cargo vendor >> .cargo/vendor
+          popd
+          tag=$(echo $GITHUB_REF | cut -d/ -f3-)
+          tarball="kata-containers-$tag-vendor.tar.gz"
+          pushd $GITHUB_WORKSPACE
+          tar -cvzf "${tarball}" src/agent/.cargo/vendor src/agent/vendor
+          GITHUB_TOKEN=${{ secrets.GIT_UPLOAD_TOKEN }} hub release edit -m "" -a "${tarball}" "${tag}" 
+          popd