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.