feat(bazel): introduce a binary stamping feature (#22176)

This grabs version control metadata and makes it available in the build, eg. to put in the version field for released artifacts

PR Close #22176

docs/BAZEL.md

@@ -17,6 +17,14 @@ you run the first build.
 
 [install]: https://bazel.build/versions/master/docs/install.html
 
+### Installation of ibazel
+
+Install interactive bazel runner / fs watcher via:
+
+```
+yarn global add @bazel/ibazel
+```
+
 ## Configuration
 
 The `WORKSPACE` file indicates that our root directory is a
@@ -112,6 +120,33 @@ Apple+Shift+D on Mac) and click on the green play icon next to the configuration
 - Open chrome at: [http://localhost:9876/debug.html](http://localhost:9876/debug.html)
 - Open chrome inspector
 
+### Debugging Bazel rules
+
+Open `external` directory which contains everything that bazel downloaded while executing the workspace file:
+```sh
+open $(bazel info output_base)/external
+```
+
+See subcommands that bazel executes (helpful for debugging):
+```sh
+bazel build //packages/core:package -s
+```
+
+To debug nodejs_binary executable paths uncomment `find . -name rollup 1>&2` (~ line 96) in
+```sh
+open $(bazel info output_base)/external/build_bazel_rules_nodejs/internal/node_launcher.sh
+```
+
+## Stamping
+
+Bazel supports the ability to include non-hermetic information from the version control system in built artifacts. This is called stamping.
+You can see an overview at https://www.kchodorow.com/blog/2017/03/27/stamping-your-builds/
+In our repo, here is how it's configured:
+
+1) In `tools/bazel_stamp_vars.sh` we run the `git` commands to generate our versioning info.
+1) In `tools/bazel.rc` we register this script as the value for the `workspace_status_command` flag. Bazel will run the script when it needs to stamp a binary.
+1) In `tools/BUILD.bazel` we have a target `stamp_data` with the special `stamp=1` attribute, which requests that Bazel run the `workspace_status_command`. The result is written to a text file that can be used as an input to other rules.
+
 ## Remote cache
 
 Bazel supports fetching action results from a cache, allowing a clean build to pick up artifacts from prior builds.

packages/BUILD.bazel

@@ -11,3 +11,8 @@ ts_library(
     name = "types",
     srcs = glob(["*.ts"]),
 )
+
+exports_files([
+    "license-banner.txt",
+    "README.md",
+])

tools/BUILD.bazel

@@ -1 +1,9 @@
-# Marker file indicating this folder is a Bazel package
+# Executes the workspace_status_command and provides the result.
+# See the section on stamping in docs/BAZEL.md
+genrule(
+    name = "stamp_data",
+    outs = ["stamp_data.txt"],
+    cmd = "cat bazel-out/volatile-status.txt > $@",
+    stamp = True,
+    visibility = ["//:__subpackages__"],
+)

tools/bazel.rc

@@ -21,6 +21,12 @@ build --symlink_prefix=dist/
 # Performance: avoid stat'ing input files
 build --watchfs
 
+###############################
+# Release support             #
+###############################
+
+build --workspace_status_command=./tools/bazel_stamp_vars.sh
+
 ###############################
 # Output                      #
 ###############################

tools/bazel_stamp_vars.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+# Generates the data used by the stamping feature in bazel.
+# A genrule with stamp=1 can read the resulting file from bazel-out/volatile-status.txt
+# See the section on stamping in docs/BAZEL.md
+
+set -u -e -E -o pipefail
+
+echo "Running: $0" >&2
+
+function onError {
+  echo "Failed to execute: $0"
+  echo ""
+}
+
+# Setup crash trap
+trap 'onError' ERR
+
+
+echo BUILD_SCM_HASH $(git rev-parse HEAD)
+
+if [[ "$(git tag)" == "" ]]; then
+  echo "No git tags found, can't stamp the build."
+  echo "Either fetch the tags:"
+  echo "       git fetch git@github.com:angular/angular.git --tags"
+  echo "or build without stamping by giving an empty workspace_status_command:"
+  echo "       bazel build --workspace_status_command= ..."
+  echo ""
+fi
+
+BUILD_SCM_VERSION_RAW=$(git describe --abbrev=7 --tags HEAD)
+
+# Find out if there are any uncommitted local changes
+# TODO(i): is it ok to use "--untracked-files=no" to ignore untracked files since they should not affect anything?
+if [[ $(git status --untracked-files=no --porcelain) ]]; then LOCAL_CHANGES="true"; else LOCAL_CHANGES="false"; fi
+echo BUILD_SCM_LOCAL_CHANGES ${LOCAL_CHANGES}
+
+# Reformat `git describe` version string into a more semver-ish string
+#   From:   5.2.0-rc.0-57-g757f886
+#   To:     5.2.0-rc.0+57.sha-757f886
+#   Or:     5.2.0-rc.0+57.sha-757f886.with-local-changes
+BUILD_SCM_VERSION="$(echo ${BUILD_SCM_VERSION_RAW} | sed -E 's/-([0-9]+)-g/+\1.sha-/g')""$( if [[ $LOCAL_CHANGES == "true" ]]; then echo ".with-local-changes"; fi)"
+echo BUILD_SCM_VERSION ${BUILD_SCM_VERSION}