buildkite: don't load images if they are not touched (v2)

v2: modify pipeline.yaml to skip load-all-images tests.
PiperOrigin-RevId: 603773497

.buildkite/hooks/pre-command

@@ -125,3 +125,17 @@ if test "${BUILDKITE_AGENT_META_DATA_QUEUE}" = "release"; then
 fi
 
 sudo sysctl -w kernel.print-fatal-signals=1
+
+pipeline_add_env() {
+  sed -i "/^env:/a\  $1: '$2'" .buildkite/pipeline.yaml
+}
+
+# Try to skip unaffected tests on pre-submits.
+# BUILDKITE_PIPELINE_ID is set only on the pipeline upload step.
+if [[ -n "${BUILDKITE_PIPELINE_ID}" && "${BUILDKITE_BRANCH}" =~ ^test/ ]]; then
+  # Skip load-all-images tests if the change doesn't affect images.
+  if ./tools/builkite-check-paths.sh images/ tools/images.mk Makefile; then
+    echo "Skip load-all-images tests"
+    pipeline_add_env SKIP_LOADING_IMAGES 1
+  fi
+fi

.buildkite/pipeline.yaml

@@ -213,14 +213,14 @@ steps:
 
   # Images tests.
   - <<: *common
-    <<: *source_test
     label: ":docker: Images (x86_64)"
+    if: build.env("SKIP_LOADING_IMAGES") == null && build.env("STAGED_BINARIES") == null
     command: make ARCH=x86_64 load-all-images
     agents:
       arch: "amd64"
   - <<: *common
-    <<: *source_test
     label: ":docker: Images (aarch64)"
+    if: build.env("SKIP_LOADING_IMAGES") == null && build.env("STAGED_BINARIES") == null
     command: make ARCH=aarch64 load-all-images
     agents:
       arch: "arm64"

tools/builkite-check-paths.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+
+# Copyright 2019 The gVisor Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Check if any changes are in specified paths. The script exits with 0 if no
+# changes were detected.
+
+set -xeo pipefail
+
+exec 1>&2
+
+git fetch origin master
+baseid=$(git merge-base origin/master "origin/${BUILDKITE_BRANCH}")
+
+git diff --stat "${baseid}" --exit-code "$@"