[Autoroll] Add lots more details and instructions in PROD.md for when license script fails
Highlights:
* Adds direct link to the roller's logs.
* Shows examples of what errors look like when they are unrelated to Skia and when they are related to Skia.
* Adds instructions on how to checkout the repo locally and run the license scripts.
Bug: skia:8657
Change-Id: I85c204d03ecaed11d1a62fda80463c67836f50f6
Reviewed-on: https://skia-review.googlesource.com/c/181801
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
diff --git a/autoroll/PROD.md b/autoroll/PROD.md
index 2cfb698..0c33f66 100644
--- a/autoroll/PROD.md
+++ b/autoroll/PROD.md
@@ -55,12 +55,52 @@
flutter_license_script_failure
------------------------------
-The Skia->Flutter roller may throw errors from Flutter's license script:
-"Failed to transition from "idle" to "active": Error when running pre-upload step: Error when running dart license script: Command exited with exit status 1: /data/engine/src/third_party/dart/tools/sdks/dart-sdk/bin/dart lib/main.dart --release --src ../../.. --out /data/engine/src/out/licenses"
-This alert means that the licence script is failing possibly due to a recent
-Skia change. Ask brianosman@ to run the script manually, or follow these steps
-on the roller to see what failed:
-* cd /data/engine/src/flutter/
-* Check to see if DEPS has the latest Skia rev. If not update it and run "/data/depot_tools/gclient sync"
-* cd /data/engine/src/flutter/tools/licenses/
-* /data/engine/src/third_party/dart/tools/sdks/dart-sdk/bin/dart lib/main.dart --release --src ../../.. --out /data/engine/src/out/licenses
+The Skia->Flutter roller has failed due to errors from Flutter's license script.
+Take a look at the cloud logs of the roller [here](https://pantheon.corp.google.com/logs/viewer?project=skia-public&advancedFilter=logName%3D%22projects%2Fskia-public%2Flogs%2Fautoroll-be-skia-flutter-autoroll%22).
+Failures due to license script errors typically look like this:
+"Failed to transition from "idle" to "active": Error when running pre-upload step: Error when running dart license script: Command exited with exit status 1:"...
+
+If the license script error looks unrelated to Skia ([example](https://github.com/flutter/flutter/issues/25679)),
+then file a bug to the Flutter team via [Github issues](https://github.com/flutter/flutter/issues/new/choose)
+with log snippets. Informing liyuqian@ about the issue might expedite the fix.
+
+If the error looks related to Skia, then take a look at the recent unrolled
+changes to see if you can identify which change caused the license script to
+fail. Sometimes adding a new directory in third_party without a LICENSE file
+can cause the script to fail ([example](https://bugs.chromium.org/p/skia/issues/detail?id=8027)).
+
+If you need to run the license scripts manually on a clean local checkout,
+then follow these steps-
+* Checkout the necessary repos:
+ * git clone https://github.com/flutter/engine
+ * cd engine
+ * echo """
+solutions = [
+ {
+ 'managed': False,
+ 'name': 'src/flutter',
+ 'url': 'git@github.com:flutter/engine.git',
+ 'custom_deps': {},
+ 'deps_file': 'DEPS',
+ 'safesync_url': '',
+ },
+]
+""" > .gclient
+ * gclient sync
+* cd src/flutter
+* Change the Skia rev in the DEPS here if necessary.
+* Run the license scripts:
+ * cd tools/licenses
+ * ../../../third_party/dart/tools/sdks/dart-sdk/bin/pub get
+ * Run dart license script to create new licenses.
+ * rm -rf ../../../out/licenses
+ * ../../../third_party/dart/tools/sdks/dart-sdk/bin/dart lib/main.dart --src ../../.. --out ../../../out/licenses --golden ../../ci/licenses_golden
+ * Copy from out dir to goldens dir. This is required for updating the release file in sky_engine/LICENSE.
+ * cp ../../../out/licenses/licenses_skia ../../ci/licenses_golden/licenses_skia
+ * Update ../../sky/packages/sky_engine/LICENSE using the dart license script.
+ * ../../../third_party/dart/tools/sdks/dart-sdk/bin/dart lib/main.dart --release --src ../../.. --out ../../../out/licenses
+
+Useful documentation links:
+* How to checkout flutter is documented [here](https://github.com/flutter/flutter/wiki/Setting-up-the-Engine-development-environment).
+* License script documentation is [here](https://github.com/flutter/engine/blob/master/tools/licenses/README.md).
+* The code for the pre-upload license step used by the autoroller is [here](https://skia.googlesource.com/buildbot/+/master/autoroll/go/repo_manager/pre_upload_steps.go).
