Experiment with Windows cross-remote Bazel tests

Add an opt-in ci-windows-cross config that sends build actions to Linux RBE while keeping test execution local on the Windows runner.

Co-authored-by: Codex <noreply@openai.com>

.bazelrc

@@ -126,6 +126,17 @@ common:ci-windows --config=ci-bazel
 common:ci-windows --build_metadata=TAG_os=windows
 common:ci-windows --repo_contents_cache=D:/a/.cache/bazel-repo-contents-cache
 
+# Experimental Windows cross-remote config: analyze on the Windows runner,
+# execute build actions on Linux RBE, then run test actions locally on Windows.
+common:ci-windows-cross --config=ci-bazel
+common:ci-windows-cross --build_metadata=TAG_os=windows-cross
+common:ci-windows-cross --config=remote
+common:ci-windows-cross --strategy=remote
+common:ci-windows-cross --strategy=TestRunner=local
+common:ci-windows-cross --platforms=//:local_windows
+common:ci-windows-cross --host_platform=//:rbe
+common:ci-windows-cross --repo_contents_cache=D:/a/.cache/bazel-repo-contents-cache
+
 # We prefer to run the build actions entirely remotely so we can dial up the concurrency.
 # We have platform-specific tests, so we want to execute the tests on all platforms using the strongest sandboxing available on each platform.
 

.github/scripts/run-bazel-ci.sh

@@ -6,6 +6,7 @@ print_failed_bazel_test_logs=0
 use_node_test_env=0
 remote_download_toplevel=0
 windows_msvc_host_platform=0
+ci_config_override=
 
 while [[ $# -gt 0 ]]; do
   case "$1" in
@@ -25,6 +26,10 @@ while [[ $# -gt 0 ]]; do
       windows_msvc_host_platform=1
       shift
       ;;
+    --ci-config=*)
+      ci_config_override="${1#--ci-config=}"
+      shift
+      ;;
     --)
       shift
       break
@@ -37,7 +42,7 @@ while [[ $# -gt 0 ]]; do
 done
 
 if [[ $# -eq 0 ]]; then
-  echo "Usage: $0 [--print-failed-test-logs] [--use-node-test-env] [--remote-download-toplevel] [--windows-msvc-host-platform] -- <bazel args> -- <targets>" >&2
+  echo "Usage: $0 [--print-failed-test-logs] [--use-node-test-env] [--remote-download-toplevel] [--windows-msvc-host-platform] [--ci-config=<config>] -- <bazel args> -- <targets>" >&2
   exit 1
 fi
 
@@ -64,17 +69,45 @@ case "${RUNNER_OS:-}" in
     ci_config=ci-windows
     ;;
 esac
+if [[ -n "$ci_config_override" ]]; then
+  ci_config="$ci_config_override"
+fi
 
 print_bazel_test_log_tails() {
   local console_log="$1"
   local testlogs_dir
   local -a bazel_info_cmd=(bazel)
+  local -a bazel_info_args=(info)
 
   if (( ${#bazel_startup_args[@]} > 0 )); then
     bazel_info_cmd+=("${bazel_startup_args[@]}")
   fi
 
-  testlogs_dir="$(run_bazel "${bazel_info_cmd[@]:1}" info bazel-testlogs 2>/dev/null || echo bazel-testlogs)"
+  # `bazel info` needs the same CI config as the failed test invocation so
+  # platform-specific output roots match. On Windows, omitting `ci-windows`
+  # would point at `local_windows-fastbuild` even when the test ran with the
+  # MSVC host platform under `local_windows_msvc-fastbuild`.
+  if [[ -n "${BUILDBUDDY_API_KEY:-}" ]]; then
+    bazel_info_args+=(
+      "--config=${ci_config}"
+      "--remote_header=x-buildbuddy-api-key=${BUILDBUDDY_API_KEY}"
+    )
+  fi
+  # Only pass flags that affect Bazel's output-root selection or repository
+  # lookup. Test/build-only flags such as execution logs or remote download
+  # mode can make `bazel info` fail, which would hide the real test log path.
+  for arg in "${post_config_bazel_args[@]}"; do
+    case "$arg" in
+      --host_platform=* | --repo_contents_cache=* | --repository_cache=*)
+        bazel_info_args+=("$arg")
+        ;;
+    esac
+  done
+
+  testlogs_dir="$(run_bazel "${bazel_info_cmd[@]:1}" \
+    --noexperimental_remote_repo_contents_cache \
+    "${bazel_info_args[@]}" \
+    bazel-testlogs 2>/dev/null || echo bazel-testlogs)"
 
   local failed_targets=()
   while IFS= read -r target; do
@@ -95,8 +128,9 @@ print_bazel_test_log_tails() {
     rel_path="${rel_path/://}"
     local test_log="${testlogs_dir}/${rel_path}/test.log"
     local reported_test_log
-    reported_test_log="$(grep -F "FAIL: ${target} " "$console_log" | sed -nE 's#.* \(see ([^)]+/test\.log)\).*#\1#p' | head -n 1 || true)"
+    reported_test_log="$(grep -F "FAIL: ${target} " "$console_log" | sed -nE 's#.* \(see (.*[\\/]test\.log)\).*#\1#p' | head -n 1 || true)"
     if [[ -n "$reported_test_log" ]]; then
+      reported_test_log="${reported_test_log//\\//}"
       test_log="$reported_test_log"
     fi
 

.github/workflows/bazel.yml

@@ -86,17 +86,20 @@ jobs:
             --print-failed-test-logs
             --use-node-test-env
           )
+          bazel_test_args=(
+            test
+            --test_tag_filters=-argument-comment-lint
+            --test_verbose_timeout_warnings
+            --build_metadata=COMMIT_SHA=${GITHUB_SHA}
+          )
           if [[ "${RUNNER_OS}" == "Windows" ]]; then
-            bazel_wrapper_args+=(--windows-msvc-host-platform)
+            bazel_wrapper_args+=(--ci-config=ci-windows-cross)
           fi
 
           ./.github/scripts/run-bazel-ci.sh \
             "${bazel_wrapper_args[@]}" \
             -- \
-            test \
-            --test_tag_filters=-argument-comment-lint \
-            --test_verbose_timeout_warnings \
-            --build_metadata=COMMIT_SHA=${GITHUB_SHA} \
+            "${bazel_test_args[@]}" \
             -- \
             "${bazel_targets[@]}"