buildscripts: simplify PSM interop Kokoro buildscripts (grpc#11121)

Integrates the new features of the the Kokoro PSM Interop install library introduced in grpc/psm-interop#73.

Nearly all common functionality was moved from per-language/per-branch PSM Interop build scripts to [psm_interop_kokoro_lib.sh](https://github.com/grpc/psm-interop/blob/main/.kokoro/psm_interop_kokoro_lib.sh):
1. The list of tests in the each test suite
2. Per-test-suite flag customization
3. `run_test` methods
4. `build_docker_images_if_needed` methods
5. Generic `build_test_app_docker_images` methods (simple docker build + docker push + docker tag). grpc-java is one exception, as it doesn't run docker directly, but a cloudbuild flow.

Now all PSM Interop jobs share the same buildscripts by all test suites:
1.  buildscript that invokes the test: `psm-interop-test-{language}.sh` (configured as `build_file` in the build cfg)
2. buildscript that builds the xDS test client/server and publishes them as a Docker image: `psm-interop-build-{language}.sh` (conventional name called from `psm_interop_kokoro_lib.sh`)

`psm-interop-test-{language}.sh`:
1. Sets `GRPC_LANGUAGE`, `BUILD_SCRIPT_DIR` environment variables.
2. Downloads the shared `psm_interop_kokoro_lib.sh` from the main branch of the psm-interop repo.
3. Sources `psm-interop-build-{language}.sh`
4. Calls `psm::run "${PSM_TEST_SUITE}"` (`PSM_TEST_SUITE` configured in the cfg file).

`psm-interop-build-{language}.sh`:
1. Defines `psm::lang::build_docker_images` which is called from `psm_interop_kokoro_lib.sh`.
2. Invokes any repo-specific logic.
3. May use `psm::build::docker_images_generic` for generic Docker build, tag, push, or provide implement its own build/publish method.

References:
- b/288578634
- See the full list of the new features at grpc/psm-interop#73.
- Additional fixes to the shared lib: grpc/psm-interop#78, grpc/psm-interop#79

buildscripts/kokoro/psm-interop-build-java.sh

@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+# Copyright 2024 gRPC 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.
+set -eo pipefail
+
+# This file defines psm::lang::build_docker_images, which is directly called
+# from psm_interop_kokoro_lib.sh.
+
+# Used locally.
+readonly BUILD_APP_PATH="interop-testing/build/install/grpc-interop-testing"
+
+#######################################
+# Builds the test app using gradle and smoke-checks its binaries
+# Globals:
+#   SRC_DIR Absolute path to the source repo.
+#   BUILD_APP_PATH
+# Arguments:
+#   None
+# Outputs:
+#   Writes the output of xds-test-client and xds-test-server --help to stderr
+#######################################
+_build_java_test_app() {
+  psm::tools::log "Building Java test app"
+  cd "${SRC_DIR}"
+
+  set -x
+  GRADLE_OPTS="-Dorg.gradle.jvmargs='-Xmx1g'" \
+  ./gradlew --no-daemon grpc-interop-testing:installDist -x test \
+    -PskipCodegen=true -PskipAndroid=true --console=plain
+  set +x
+
+  psm::tools::log "Test-run grpc-java PSM interop binaries"
+  psm::tools::run_ignore_exit_code "${SRC_DIR}/${BUILD_APP_PATH}/bin/xds-test-client" --help
+  psm::tools::run_ignore_exit_code "${SRC_DIR}/${BUILD_APP_PATH}/bin/xds-test-server" --help
+}
+
+#######################################
+# Builds test app Docker images and pushes them to GCR
+# Globals:
+#   BUILD_APP_PATH
+#   SERVER_IMAGE_NAME: Test server Docker image name
+#   CLIENT_IMAGE_NAME: Test client Docker image name
+#   GIT_COMMIT: SHA-1 of git commit being built
+#   TESTING_VERSION: version branch under test, f.e. v1.42.x, master
+# Arguments:
+#   None
+# Outputs:
+#   Writes the output of `gcloud builds submit` to stdout, stderr
+#######################################
+psm::lang::build_docker_images() {
+  local java_build_log="${BUILD_LOGS_ROOT}/build-lang-java.log"
+  _build_java_test_app |& tee "${java_build_log}"
+
+  psm::tools::log "Building Java xDS interop test app Docker images"
+  local docker_dir="${SRC_DIR}/buildscripts/xds-k8s"
+  local build_dir
+  build_dir="$(mktemp -d)"
+
+  # Copy Docker files, log properties, and the test app to the build dir
+  {
+    cp -v "${docker_dir}/"*.Dockerfile "${build_dir}"
+    cp -v "${docker_dir}/"*.properties "${build_dir}"
+    cp -rv "${SRC_DIR}/${BUILD_APP_PATH}" "${build_dir}"
+  } >> "${java_build_log}"
+
+
+  # cloudbuild.yaml substitution variables
+  local substitutions=""
+  substitutions+="_SERVER_IMAGE_NAME=${SERVER_IMAGE_NAME},"
+  substitutions+="_CLIENT_IMAGE_NAME=${CLIENT_IMAGE_NAME},"
+  substitutions+="COMMIT_SHA=${GIT_COMMIT},"
+  substitutions+="BRANCH_NAME=${TESTING_VERSION},"
+
+  # Run Google Cloud Build
+  gcloud builds submit "${build_dir}" \
+    --config="${docker_dir}/cloudbuild.yaml" \
+    --substitutions="${substitutions}" \
+    | tee -a "${java_build_log}"
+}

buildscripts/kokoro/psm-interop-test-java.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+set -eo pipefail
+
+# Input parameters to psm:: methods of the install script.
+readonly GRPC_LANGUAGE="java"
+readonly BUILD_SCRIPT_DIR="$(dirname "$0")"
+
+# Used locally.
+readonly TEST_DRIVER_INSTALL_SCRIPT_URL="https://raw.githubusercontent.com/${TEST_DRIVER_REPO_OWNER:-grpc}/psm-interop/${TEST_DRIVER_BRANCH:-main}/.kokoro/psm_interop_kokoro_lib.sh"
+
+psm::lang::source_install_lib() {
+  echo "Sourcing test driver install script from: ${TEST_DRIVER_INSTALL_SCRIPT_URL}"
+  local install_lib
+  # Download to a tmp file.
+  install_lib="$(mktemp -d)/psm_interop_kokoro_lib.sh"
+  curl -s --retry-connrefused --retry 5 -o "${install_lib}" "${TEST_DRIVER_INSTALL_SCRIPT_URL}"
+  # Checksum.
+  if command -v sha256sum &> /dev/null; then
+    echo "Install script checksum:"
+    sha256sum "${install_lib}"
+  fi
+  source "${install_lib}"
+}
+
+psm::lang::source_install_lib
+source "${BUILD_SCRIPT_DIR}/psm-interop-build-${GRPC_LANGUAGE}.sh"
+psm::run "${PSM_TEST_SUITE}"

buildscripts/kokoro/psm-security.cfg

@@ -1,7 +1,7 @@
 # Config file for internal CI
 
 # Location of the continuous shell script in repository.
-build_file: "grpc-java/buildscripts/kokoro/psm-security.sh"
+build_file: "grpc-java/buildscripts/kokoro/psm-interop-test-java.sh"
 timeout_mins: 240
 
 action {
@@ -11,3 +11,7 @@ action {
     strip_prefix: "artifacts"
   }
 }
+env_vars {
+  key: "PSM_TEST_SUITE"
+  value: "security"
+}

buildscripts/kokoro/xds_k8s_lb.cfg

@@ -1,7 +1,7 @@
 # Config file for internal CI
 
 # Location of the continuous shell script in repository.
-build_file: "grpc-java/buildscripts/kokoro/xds_k8s_lb.sh"
+build_file: "grpc-java/buildscripts/kokoro/psm-interop-test-java.sh"
 timeout_mins: 180
 
 action {
@@ -11,3 +11,7 @@ action {
     strip_prefix: "artifacts"
   }
 }
+env_vars {
+  key: "PSM_TEST_SUITE"
+  value: "lb"
+}