ci: build vendor tarball and create new release when new tag is pushed

This adds two new CI jobs that run when a new tag is pushed to this
repo: one to tar up the vendored dependencies and another one to push
the tarball as an asset in a new gitlab "release" for the tag.

fixes: #5

.gitlab-ci.yml

@@ -5,10 +5,13 @@ image: alpine:edge
 
 variables:
   GOFLAGS: "-buildvcs=false"
+  PACKAGE_REGISTRY_URL: "${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/mkinitfs-vendor-${CI_COMMIT_TAG}/${CI_COMMIT_TAG}"
 
 stages:
   - lint
   - build
+  - vendor
+  - release
 
 # defaults for "only"
 # We need to run the CI jobs in a "merge request specific context", if CI is
@@ -34,3 +37,27 @@ build:
     - make
   artifacts:
     expire_in: 1 week
+
+vendor:
+  stage: vendor
+  image: alpine:latest
+  only:
+    - tags
+  before_script:
+    - apk -q add curl go make
+  script:
+    - |
+      make VERSION="${CI_COMMIT_TAG}" vendor
+      curl --header "JOB-TOKEN: ${CI_JOB_TOKEN}" --upload-file "mkinitfs-vendor-${CI_COMMIT_TAG}.tar.gz" "${PACKAGE_REGISTRY_URL}/"
+      curl --header "JOB-TOKEN: ${CI_JOB_TOKEN}" --upload-file "mkinitfs-vendor-${CI_COMMIT_TAG}.tar.gz.sha512" "${PACKAGE_REGISTRY_URL}/"
+
+release:
+  stage: release
+  image: registry.gitlab.com/gitlab-org/release-cli:latest
+  only:
+    - tags
+  script:
+    - |
+      release-cli create --name "Release $CI_COMMIT_TAG" --tag-name $CI_COMMIT_TAG \
+        --assets-link "{\"name\":\"mkinitfs-vendor-${CI_COMMIT_TAG}.tar.gz\",\"url\":\"${PACKAGE_REGISTRY_URL}/mkinitfs-vendor-${CI_COMMIT_TAG}.tar.gz\"}" \
+        --assets-link "{\"name\":\"mkinitfs-vendor-${CI_COMMIT_TAG}.tar.gz.sha512\",\"url\":\"${PACKAGE_REGISTRY_URL}/mkinitfs-vendor-${CI_COMMIT_TAG}.tar.gz.sha512\"}"