Upload a release artifact when pushing a tag v*

The github actions API doesn't play well with per commit artifacts. For
now we create a release when pushing a tag.

Consuming the per commit artifacts w/o the github actions API is blocked
by this: actions/upload-artifact#50

.github/workflows/ci.yml

@@ -150,11 +150,17 @@ jobs:
     - name: workspace_v2
       run: make workspace_v2
 
-  # This uploads `xchammer.zip` as an artifact that can be pulled in via the `WORKSPACE`
-  # 1. Open github.com/your-org/xchammer
-  # 2. Navigate to Actions
-  # 3. Navigate to `Artifacts`
-  # 4. Put `xchammer.zip` into the WORKSPACE
+  # This uploads `xchammer.zip` as an artifact to github actions
+  # For issues mentioned here
+  # https://github.com/actions/upload-artifact/issues/50
+  # The Github URL can't be used with Bazel directly in an `http_archive`
+  # At the time of writing the only way to consume it is to:
+  # - get the release URL with the github actions API which is valid for 1 minute
+  # - pull the zip from that URL and re-host it: or somehow use it locally.
+  # - it'd probably be possible to impalement as a github actions repository
+  #   and that's a lot of unwarranted complexity to integrate XCHammer.
+  #
+  # See README.md of how to use the artifact with Bazel
   make_release:
     name: make_release
     runs-on: macOS-latest
@@ -178,5 +184,5 @@ jobs:
             echo ::set-env name=BAZEL_BIN::$(readlink bazel-bin)
       - uses: actions/upload-artifact@v2
         with:	
-          name: xchammer.zip
+          name: xchammer
           path: ${{ env.BAZEL_BIN }}/xchammer_dist_repo.zip

.github/workflows/ci_push.yml

@@ -155,11 +155,17 @@ jobs:
     - name: workspace_v2
       run: make workspace_v2
 
-  # This uploads `xchammer.zip` as an artifact that can be pulled in via the `WORKSPACE`
-  # 1. Open github.com/your-org/xchammer
-  # 2. Navigate to Actions
-  # 3. Navigate to `Artifacts`
-  # 4. Put `xchammer.zip` into the WORKSPACE
+  # This uploads `xchammer.zip` as an artifact to github actions
+  # For issues mentioned here
+  # https://github.com/actions/upload-artifact/issues/50
+  # The Github URL can't be used with Bazel directly in an `http_archive`
+  # At the time of writing the only way to consume it is to:
+  # - get the release URL with the github actions API which is valid for 1 minute
+  # - pull the zip from that URL and re-host it: or somehow use it locally.
+  # - it'd probably be possible to impalement as a github actions repository
+  #   and that's a lot of unwarranted complexity to integrate XCHammer.
+  #
+  # See README.md of how to use the artifact with Bazel
   make_release:
     name: make_release
     runs-on: macOS-latest
@@ -183,5 +189,5 @@ jobs:
             echo ::set-env name=BAZEL_BIN::$(readlink bazel-bin)
       - uses: actions/upload-artifact@v2
         with:	
-          name: xchammer.zip
+          name: xchammer
           path: ${{ env.BAZEL_BIN }}/xchammer_dist_repo.zip

.github/workflows/upload_release_artifact.yml

@@ -0,0 +1,46 @@
+# This workflow cuts a per commit binary release of XCHammer and uploads
+# the binary release WORKSPACE for later consumption.
+#
+# Basically push a tag to github for the commit and this will append the
+# release artifact
+#
+# Ideally we'd create a Bazel consumeable artifact per commit but using github
+# actions w/o any other systems it's not so possible
+# https://github.com/actions/upload-artifact/issues/50
+on:
+  push:
+    tags:
+    - 'v*' # Push events to matching v*, i.e. v1.0, v20.15.10
+
+name: Upload Release Artifact
+
+jobs:
+  build:
+    name: create_release
+    runs-on: macOS-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: make_release
+        run: make release
+      - name: create_release
+        id: create_release
+        uses: actions/create-release@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          tag_name: ${{ github.ref }}
+          release_name: ${{ github.ref }}
+          draft: false
+          prerelease: false
+      - name: upload_release_asset
+        id: upload-release-asset 
+        uses: actions/upload-release-asset@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          upload_url: ${{ steps.create_release.outputs.upload_url }} # This pulls from the CREATE RELEASE step above, referencing it's ID to get its outputs object, which include a `upload_url`. See this blog post for more info: https://jasonet.co/posts/new-features-of-github-actions/#passing-data-to-future-steps 
+          asset_path: bazel-bin/xchammer_dist_repo.zip
+          asset_name: xchammer.zip
+          asset_content_type: application/zip
+
+

README.md

@@ -39,24 +39,39 @@ First, pull XCHammer into the `WORKSPACE` file:
 _Ideally, pull in a release optimized binary build to keep XCHammer's
 dependencies, Swift version, Xcode version, compiler flags, Bazel version, and
 build time outside of the main iOS/macOS application's WORKSPACE. To easily
-achieve this, main github CI worfklows create a binary release artifact for
-each commit:_
+achieve this, github CI creates a binary release artifact on receiving a new
+tag._
 
 ```py
 # WORKSPACE
-# To get the artifact URL per commit: 
-# - Navigate to the Actions tab on https://github.com/your-org/xchammer
-# - Get the URL of `xchammer.zip` e.g.
-#   https://github.com/pinterest/xchammer/suites/{suite_number}/artifacts/{artifact_number}
+# Recommended approach - the CI auto releases when you push a tag matching `v*`
+# The release prefix is the _tested_ bazel version, and XCHammer is often
+# forwards and backwards compatible
 http_archive(
     name = "xchammer",
-    urls = [ "https://github.com/pinterest/xchammer/suites/{suite_number}/artifacts/{artifact_number}" ],
+    urls = [ "https://github.com/pinterest/xchammer/releases/download/v3.4.1.0/xchammer.zip" ],
 )
+
+# Vendor a binary release of xchammer e.g. from a github action `artifact` on a PR
+#  https://github.com/pinterest/xchammer/pull/262/checks?check_run_id=1195532626
+# local_repository(
+#    name = "xchammer",
+#    path = "tools/xchammer"
+# )
+
+# Pull from source
+# git_repository(
+#    name = "xchammer",
+#    remote = "https://github.com/pinterest/xchammer.git",
+#    commit = "[COMMIT_SHA]"
+# )
 ```
 _note: for development, `make build` and the `xchammer_dev_repo` target allow a
 WORKSPACE to consume XCHammer built out of tree but point to the latest build,
-symlinked in `bazel-bin`. It's also possible to use `local_repository` and
-override it using `--override_repository=xchammer=/path/to/xchammer`_
+symlinked in `bazel-bin`:
+`--override_repository=xchammer=/path/to/xchammer/bazel-bin/xchammer_dev_repo`.
+It's also possible to use `local_repository` and override it using
+`--override_repository=xchammer=/path/to/xchammer`_
 
 Next, create an `xcode_project` target including targets:
 ```