update readme for LUCI (#29023)

* update readme for LUCI

* Update README.md

dev/bots/README.md

@@ -5,41 +5,37 @@ This directory exists to support building Flutter on our build infrastructure.
 The results of such builds are viewable at:
 * https://cirrus-ci.com/github/flutter/flutter/master
   - Testing done on PRs and submitted changes on GitHub.
-* https://build.chromium.org/p/client.flutter/console
+* https://ci.chromium.org/p/flutter/
   - Additional testing and processing done after changes are submitted.
 
-The Chromium infra bots do not allow forcing new builds from outside
-the Google network. Contact @eseidelGoogle or another Google member of
-the Flutter team if you need to do that.
-
-The [Cirrus](https://cirrus-ci.org)-based bots run the
-[`test.dart`](test.dart) script for each PR and submission. This does
-testing for the tools, for the framework, and (for submitted changes
-only) rebuilds and updates the master branch API docs
-[staging site](https://master-docs-flutter-io.firebaseapp.com).
-For tagged dev and beta builds, it also builds and deploys the gallery
-app to the app stores. It is configured by the
-[.cirrus.yml](/.cirrus.yml).
-
-We also have post-commit testing with actual devices, in what we call
-our [devicelab](../dev/devicelab/README.md).
-
-## Chromium infra bots
-
-This part of our infrastructure is broken into two parts. A buildbot
-master specified by our
-[builders.pyl](https://chromium.googlesource.com/chromium/tools/build.git/+/master/masters/master.client.flutter/builders.pyl)
-file, and a [set of
-recipes](https://chromium.googlesource.com/chromium/tools/build.git/+/master/scripts/slave/recipes/flutter)
-which we run on that master. Both of these technologies are highly
-specific to Google's Chromium project. We're just borrowing some of
-their infrastructure.
+The LUCI infra requires permissions to retrigger or schedule builds. Contact
+@kf6gpe or another Google member of the Flutter team if you need to do that.
+
+The [Cirrus](https://cirrus-ci.org)-based bots run the [`test.dart`](test.dart)
+script for each PR and submission. This does testing for the tools, for the
+framework, and (for submitted changes only) rebuilds and updates the master
+branch API docs [staging site](https://master-docs.flutter.dev/).
+For tagged dev and beta builds, it also builds and deploys the gallery app to
+the app stores. It is configured by the [.cirrus.yml](/.cirrus.yml).
+
+We also have post-commit testing with actual devices, in what we call our
+[devicelab](../dev/devicelab/README.md).
+
+## LUCI (Layered Universal Continuous Intergration)
+
+A [set of recipes](https://chromium.googlesource.com/chromium/tools/build.git/+/master/scripts/slave/recipes/flutter)
+are run on Windows, Linux, and Mac machines. The configuration for how many
+machines and what kind are managed internally by Google. Contact @kf6gpe or
+another Google member of the Flutter team if you suspect changes are needed
+there. Both of these technologies are highly specific to the [LUCI](https://github.com/luci)
+project, which is the successor to Chromium's infra. We're just borrowing some
+of their infrastructure.
 
 ### Prerequisites
 
 To work on this infrastructure you will need:
 
-- [depot_tools](http://www.chromium.org/developers/how-tos/install-depot-tools)
+- [depot_tools](https://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/depot_tools_tutorial.html#_setting_up)
 - Python package installer: `sudo apt-get install python-pip`
 - Python coverage package (only needed for `training_simulation`): `sudo pip install coverage`
 
@@ -58,7 +54,8 @@ To run prepare_package.dart locally:
 
 ### Getting the code
 
-The following will get way more than just recipe code, but it _will_ get the recipe code:
+The following will get way more than just recipe code, but it _will_ get the
+recipe code:
 
 ```bash
 mkdir chrome_infra
@@ -82,7 +79,7 @@ and
 - build/scripts/slave/recipes/flutter/flutter.py
 - build/scripts/slave/recipes/flutter/engine.py
 
-Recipes are just Python.  They are
+Recipes are just Python with some limitations on what can be imported. They are
 [documented](https://github.com/luci/recipes-py/blob/master/doc/user_guide.md)
 by the [luci/recipes-py github project](https://github.com/luci/recipes-py).
 
@@ -90,33 +87,30 @@ The typical cycle for editing a recipe is:
 
 1. Make your edits (probably to files in
    `//chrome_infra/build/scripts/slave/recipes/flutter`).
-1. Update the tests. Run `build/scripts/slave/recipes.py test train` to update
+2. Update the tests. Run `build/scripts/slave/recipes.py test train` to update
    existing expected output to match the new output. Verify completely new test
-   cases by altering the `GenTests` method of the recipe.
-   The recipe is required to have 100% test coverage.
-1. Run `build/scripts/slave/recipes.py run flutter/<repo> slavename=<slavename>
-   mastername=client.flutter buildername=<buildername> buildnumber=1234` where `<repo>` is one
-   of `flutter` or `engine`, and `slavename` and `buildername` can be looked up
-   from the *Build Properties* section of a [recent
+   cases by altering the `GenTests` method of the recipe. The recipe is required
+   to have 100% test coverage.
+3. Run `build/scripts/slave/recipes.py run flutter/<repo> slavename=<slavename>
+   mastername=client.flutter buildername=<buildername>
+   buildnumber=1234` where `<repo>` is one of `flutter` or `engine`, and
+   `slavename` and `buildername` can be looked up from the *Build Properties*
+   section of a [recent
    build](https://build.chromium.org/p/client.flutter/one_line_per_build).
-1. To submit a CL, you need a local branch first (`git checkout -b [some branch name]`).
-1. Upload the patch (`git commit`, `git cl upload`) and send it to someone in
+4. To submit a CL, you need a local branch first (`git checkout -b [some branch name]`).
+5. Upload the patch (`git commit`, `git cl upload`) and send it to someone in
    the `recipes/flutter/OWNERS` file for review.
 
-### Editing the client.flutter buildbot master
+### The infra config repository
 
-Flutter uses Chromium's fancy
-[builders.pyl](https://chromium.googlesource.com/infra/infra/+/master/doc/users/services/buildbot/builders.pyl.md)
-master generation system.  Chromium hosts 100s (if not 1000s) of buildbot
-masters and thus has lots of infrastructure for turning them up and down.
-Eventually all of buildbot is planned to be replaced by other infrastructure,
-but for now flutter has its own client.flutter master.
+The [flutter/infra](https://github.com/flutter/infra) repository contains
+configuration files for the dashboard, builder groups, scheduling, and
+individual builders. Edits to this may require changes other internal Google
+repositories - e.g., to change the operating system or number of machines. If
+you want to do that, reach out to @kf6gpe or another member of the Google team.
 
-You would need to edit client.flutter's master in order to add slaves (talk to
-@eseidelGoogle), add builder groups, or to change the html layout of
-https://build.chromium.org/p/client.flutter.  Carefully follow the [builders.pyl
-docs](https://chromium.googlesource.com/infra/infra/+/master/doc/users/services/buildbot/builders.pyl.md)
-to do so.
+Each configuration file in that repository has a link in the top comments to a
+schema that describes available properties.
 
 ### Future Directions
 
@@ -130,11 +124,13 @@ tried, but it's not quite ready.
 
 ### Android Tools
 
-The Android SDK and NDK used by Flutter's Chrome infra bots are stored in Google Cloud. During the build a bot runs the
-`download_android_tools.py` script that downloads the required version of the Android SDK into `dev/bots/android_tools`.
+The Android SDK and NDK used by Flutter's Chrome infra bots are stored in Google
+Cloud. During the build a bot runs the `download_android_tools.py` script that
+downloads the required version of the Android SDK into `dev/bots/android_tools`.
 
-To check which components are currently installed, download the current SDK stored in Google Cloud using the
-`download_android_tools.py` script, then `dev/bots/android_tools/sdk/tools/bin/sdkmanager --list`. If you find that some
+To check which components are currently installed, download the current SDK
+stored in Google Cloud using the `download_android_tools.py` script, then
+`dev/bots/android_tools/sdk/tools/bin/sdkmanager --list`. If you find that some
 components need to be updated or installed, follow the steps below:
 
 #### How to update Android SDK on Google Cloud Storage
@@ -145,13 +141,17 @@ components need to be updated or installed, follow the steps below:
 
 2. Use the UI to choose the packages you want to install and/or update.
 
-3. Run `dev/bots/android_tools/sdk/tools/bin/sdkmanager --update`. On Windows, run `sdkmanager.bat` instead. If the
-   process fails with an error saying that it is unable to move files (Windows makes files and directories read-only
-   when another process is holding them open), make a copy of the `dev/bots/android_tools/sdk/tools` directory, run
-   the `sdkmanager.bat` from the copy, and use the `--sdk_root` option pointing at `dev/bots/android_tools/sdk`.
-
-4. Run `dev/bots/android_tools/sdk/tools/bin/sdkmanager --licenses` and accept the licenses for the newly installed
-   components. It also helps to run this command a second time and make sure that it prints "All SDK package licenses
+3. Run `dev/bots/android_tools/sdk/tools/bin/sdkmanager --update`. On Windows,
+   run `sdkmanager.bat` instead. If the process fails with an error saying that
+   it is unable to move files (Windows makes files and directories read-only
+   when another process is holding them open), make a copy of the
+   `dev/bots/android_tools/sdk/tools` directory, run the `sdkmanager.bat` from
+   the copy, and use the `--sdk_root` option pointing at
+   `dev/bots/android_tools/sdk`.
+
+4. Run `dev/bots/android_tools/sdk/tools/bin/sdkmanager --licenses` and accept
+   the licenses for the newly installed components. It also helps to run this
+   command a second time and make sure that it prints "All SDK package licenses
    accepted".
 
 5. Run upload_android_tools.py -t sdk