diff --git a/.kokoro/psm_interop_kokoro_lib.sh b/.kokoro/psm_interop_kokoro_lib.sh
index c75f4864..0ee9fc1b 100644
--- a/.kokoro/psm_interop_kokoro_lib.sh
+++ b/.kokoro/psm_interop_kokoro_lib.sh
@@ -12,23 +12,607 @@
 # 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.
-# TODO(sergiitk): move to grpc/grpc when implementing support of other languages
 set -eo pipefail
 
-# Constants
-readonly PYTHON_VERSION="${PYTHON_VERSION:-3.10}"
-# Test driver
-readonly TEST_DRIVER_REPO_NAME="psm-interop"
-readonly TEST_DRIVER_REPO_URL="https://github.com/${TEST_DRIVER_REPO_OWNER:-grpc}/psm-interop.git"
-readonly TEST_DRIVER_BRANCH="${TEST_DRIVER_BRANCH:-main}"
-readonly TEST_DRIVER_PATH=""
-readonly TEST_DRIVER_PROTOS_PATH="protos/grpc/testing"
-readonly FORCE_TESTING_VERSION="${FORCE_TESTING_VERSION:-}"
+# Prepend verbose mode commands (xtrace) with the date.
+PS4='+ $(date "+[%H:%M:%S %Z]")\011 '
 
+# --- Constants ---
 # GKE cluster identifiers.
 readonly GKE_CLUSTER_PSM_LB="psm-lb"
 readonly GKE_CLUSTER_PSM_SECURITY="psm-security"
 readonly GKE_CLUSTER_PSM_BASIC="psm-basic"
+# TODO(sergiitk): 'if' can be removed when DOCKER_REGISTRY removed from buildscripts.
+if [[ -z "${DOCKER_REGISTRY}" ]] ; then
+  readonly DOCKER_REGISTRY="us-docker.pkg.dev"
+fi
+# Test driver
+readonly TEST_DRIVER_REPO_NAME="psm-interop"
+readonly TEST_DRIVER_PATH=""
+readonly TEST_DRIVER_PROTOS_PATH="protos/grpc/testing"
+
+# --- Injectable constants ---
+readonly PYTHON_VERSION="${PYTHON_VERSION:-3.10}"
+
+# Test driver
+readonly TEST_DRIVER_REPO_OWNER="${TEST_DRIVER_REPO_OWNER:-grpc}"
+readonly TEST_DRIVER_REPO_URL="https://github.com/${TEST_DRIVER_REPO_OWNER}/${TEST_DRIVER_REPO_NAME}.git"
+readonly TEST_DRIVER_BRANCH="${TEST_DRIVER_BRANCH:-main}"
+
+# Forces image build, even if a tag with GIT_COMMIT already exists.
+readonly PSM_FORCE_IMAGE_BUILD="${PSM_FORCE_IMAGE_BUILD:-0}"
+# Overrides the TESTING_VERSION. Can be used to force versioned image tag, see is_version_branch.
+readonly PSM_FORCE_TESTING_VERSION="${PSM_FORCE_TESTING_VERSION:-}"
+# Overrides the list of test to run. A whitespace-separated string. Example:
+# PSM_TESTS="app_net_test baseline_test"
+readonly PSM_TESTS="${PSM_TESTS:-}"
+# A space-separated string with extra flags to append to the test driver arguments.
+# Can be used to execute a run and test a new flag value, f.e.:
+# PSM_EXTRA_FLAGS="--noenable_workload_identity --td_bootstrap_image=us-docker.pkg.dev/new-image..."
+# In addition, can be used to run a single test in a suite. F.e. to run only test_mtls in security_test:
+# PSM_TESTS="security_test" PSM_EXTRA_FLAGS="SecurityTest.test_mtls"
+readonly PSM_EXTRA_FLAGS="${PSM_EXTRA_FLAGS:-}"
+
+
+# --- LB TESTS ------------------------
+
+#######################################
+# LB Test Suite setup.
+# Outputs:
+#   Prints activated cluster names.
+#######################################
+psm::lb::setup() {
+  activate_gke_cluster GKE_CLUSTER_PSM_LB
+  activate_secondary_gke_cluster GKE_CLUSTER_PSM_LB
+}
+
+#######################################
+# Prepares the list of tests in PSM LB test suite.
+# Globals:
+#   TESTING_VERSION: The version branch under test, f.e. master, dev, v1.42.x.
+#   TESTS: Populated with tests in the test suite.
+#######################################
+psm::lb::get_tests() {
+  TESTS=(
+    "affinity_test"
+    "api_listener_test"
+    "app_net_test"
+    "change_backend_service_test"
+    "custom_lb_test"
+    "failover_test"
+    "outlier_detection_test"
+    "remove_neg_test"
+    "round_robin_test"
+  )
+  # master-only tests
+  if [[ "${TESTING_VERSION}" =~ "master" ]]; then
+      psm::tools::log "Appending master-only tests to the LB suite."
+      TESTS+=(
+        "bootstrap_generator_test"
+        "subsetting_test"
+      )
+  fi
+}
+
+#######################################
+# Executes LB test case.
+# Globals:
+#   PSM_TEST_FLAGS: The array with flags for the test
+# Arguments:
+#   Test case name
+# Outputs:
+#   Writes the output of test execution to stdout, stderr
+#   Test xUnit report to ${TEST_XML_OUTPUT_DIR}/${test_name}/sponge_log.xml
+#######################################
+psm::lb::run_test() {
+  local test_name="${1:?${FUNCNAME[0]} missing the test name argument}"
+  psm::run::finalize_test_flags "${test_name}"
+  psm::tools::run_verbose python -m "tests.${test_name}" "${PSM_TEST_FLAGS[@]}"
+}
+
+# --- Security TESTS ------------------
+
+#######################################
+# Security Test Suite setup.
+# Outputs:
+#   Prints activated cluster names.
+#######################################
+psm::security::setup() {
+  activate_gke_cluster GKE_CLUSTER_PSM_SECURITY
+}
+
+#######################################
+# Prepares the list of tests in PSM Security test suite.
+# Globals:
+#   TESTS: Populated with tests in PSM Security test suite.
+#######################################
+psm::security::get_tests() {
+  TESTS=(
+    "baseline_test"
+    "security_test"
+    "authz_test"
+  )
+}
+
+#######################################
+# Executes Security test case
+# Globals:
+#   PSM_TEST_FLAGS: The array with flags for the test
+#   GRPC_LANGUAGE: The name of gRPC languages under test
+# Arguments:
+#   Test case name
+# Outputs:
+#   Writes the output of test execution to stdout, stderr
+#   Test xUnit report to ${TEST_XML_OUTPUT_DIR}/${test_name}/sponge_log.xml
+#######################################
+psm::security::run_test() {
+  local test_name="${1:?${FUNCNAME[0]} missing the test name argument}"
+
+  # Only java supports extra checks for certificate matches (via channelz socket info).
+  if [[ "${GRPC_LANGUAGE}" != "java"  ]]; then
+    PSM_TEST_FLAGS+=("--nocheck_local_certs")
+  fi
+
+  psm::run::finalize_test_flags "${test_name}"
+  psm::tools::run_verbose python -m "tests.${test_name}" "${PSM_TEST_FLAGS[@]}"
+}
+
+# --- URL Map TESTS ------------------
+
+#######################################
+# URL Map Test Suite setup.
+# Outputs:
+#   Prints activated cluster names.
+#######################################
+psm::url_map::setup() {
+  activate_gke_cluster GKE_CLUSTER_PSM_BASIC
+}
+
+#######################################
+# Prepares the list of tests in URL Map test suite.
+# Globals:
+#   TESTS: Populated with tests in the test suite.
+#######################################
+psm::url_map::get_tests() {
+  TESTS=("url_map")
+}
+
+#######################################
+# Executes URL Map test case
+# Globals:
+#   PSM_TEST_FLAGS: The array with flags for the test
+# Arguments:
+#   Test case name
+# Outputs:
+#   Writes the output of test execution to stdout, stderr
+#   Test xUnit report to ${TEST_XML_OUTPUT_DIR}/${test_name}/sponge_log.xml
+#######################################
+psm::url_map::run_test() {
+  local test_name="${1:?${FUNCNAME[0]} missing the test name argument}"
+  PSM_TEST_FLAGS+=(
+    "--flagfile=config/url-map.cfg"
+  )
+  psm::run::finalize_test_flags "${test_name}"
+  psm::tools::run_verbose python -m "tests.${test_name}" "${PSM_TEST_FLAGS[@]}"
+}
+
+# --- CSM TESTS ------------------
+
+#######################################
+# CSM Test Suite setup.
+# Outputs:
+#   Prints activated cluster names.
+#######################################
+psm::csm::setup() {
+  activate_gke_cluster GKE_CLUSTER_PSM_CSM
+}
+
+#######################################
+# Prepares the list of tests in CSM test suite.
+# Globals:
+#   TESTS: Populated with tests in the test suite.
+#######################################
+psm::csm::get_tests() {
+  TESTS=(
+    "gamma.gamma_baseline_test"
+    "gamma.affinity_test"
+    "gamma.affinity_session_drain_test"
+    "gamma.csm_observability_test"
+    "app_net_ssa_test"
+  )
+}
+
+#######################################
+# Executes CSM test case
+# Globals:
+#   PSM_TEST_FLAGS: The array with flags for the test
+# Arguments:
+#   Test case name
+# Outputs:
+#   Writes the output of test execution to stdout, stderr
+#   Test xUnit report to ${TEST_XML_OUTPUT_DIR}/${test_name}/sponge_log.xml
+#######################################
+psm::csm::run_test() {
+  local test_name="${1:?${FUNCNAME[0]} missing the test name argument}"
+  PSM_TEST_FLAGS+=(
+    "--flagfile=config/common-csm.cfg"
+  )
+  psm::run::finalize_test_flags "${test_name}"
+  psm::tools::run_verbose python -m "tests.${test_name}" "${PSM_TEST_FLAGS[@]}"
+}
+
+# --- Common test run logic -----------
+
+#######################################
+# Prepares and runs the test suite.
+#
+# Main entry function to be used by the buildscripts.
+# Provisions necessary software, configures the test driver, and executes the test suite.
+#
+# Globals:
+#   KOKORO_ARTIFACTS_DIR
+#   GITHUB_REPOSITORY_NAME
+#   GRPC_LANGUAGE
+#   SRC_DIR: Populated with absolute path to the source repo
+#   TEST_DRIVER_REPO_DIR: Populated with the path to the repo containing
+#                         the test driver
+#   TEST_DRIVER_FULL_DIR: Populated with the path to the test driver source code
+#   TEST_DRIVER_FLAGFILE: Populated with relative path to test driver flagfile
+#   TEST_XML_OUTPUT_DIR: Populated with the path to test xUnit XML report
+#   GIT_ORIGIN_URL: Populated with the origin URL of git repo used for the build
+#   GIT_COMMIT: Populated with the SHA-1 of git commit being built
+#   GIT_COMMIT_SHORT: Populated with the short SHA-1 of git commit being built
+#   KUBE_CONTEXT: Populated with name of kubectl context with GKE cluster access
+# Arguments:
+#   Test suite name, one of (lb, security, url_map)
+# Outputs:
+#   Writes the output of test execution to stdout, stderr
+#######################################
+psm::run() {
+  local test_suite="${1:?${FUNCNAME[0]} missing the test suite argument}"
+  psm::tools::log "Starting PSM Interop tests: ${test_suite}"
+
+  psm::setup::docker_image_names "${GRPC_LANGUAGE}" "${test_suite}"
+
+  case "${test_suite}" in
+    lb | security | url_map | csm)
+      psm::setup::generic_test_suite "${test_suite}"
+      ;;
+    *)
+      psm::tools::log "Unknown Test Suite: ${test_suite}"
+      exit 1
+      ;;
+  esac
+
+  psm::run::test_suite "${test_suite}"
+  psm::tools::log "PSM Interop tests completed: ${test_suite}"
+}
+
+#######################################
+# Executes tests in the test suite
+# Globals:
+#   TEST_DRIVER_FULL_DIR
+#   TESTS: the list of the tests to execute
+# Arguments:
+#   Test suite name.
+# Outputs:
+#   Each test to stdout.
+#######################################
+psm::run::test_suite() {
+  local test_suite="${1:?${FUNCNAME[0]} missing the test suite argument}"
+  cd "${TEST_DRIVER_FULL_DIR}"
+  local failed_tests=0
+  for test_name in "${TESTS[@]}"; do
+    psm::run::test "${test_suite}" "${test_name}" || (( ++failed_tests ))
+    psm::tools::log "Finished ${test_suite} suite test: ${test_name}"
+    echo
+  done
+  psm::tools::log "Failed test suites: ${failed_tests}"
+}
+
+#######################################
+# Executes a single test case of given test suite.
+# Globals:
+#   TEST_DRIVER_FLAGFILE: Relative path to test driver flagfile
+#   KUBE_CONTEXT: The name of kubectl context with GKE cluster access
+#   TEST_XML_OUTPUT_DIR: Output directory for the test xUnit XML report
+#   CLIENT_IMAGE_NAME: Test client Docker image name
+#   GIT_COMMIT: SHA-1 of git commit being built
+#   TESTING_VERSION: version branch under test: used by the framework to
+#                     determine the supported PSM features.
+# Arguments:
+#   Test suite name
+#   Test case name
+# Outputs:
+#   Writes the output of test execution to stdout, stderr
+#   Test xUnit report to ${TEST_XML_OUTPUT_DIR}/${test_name}/sponge_log.xml
+#######################################
+psm::run::test() {
+  # Test driver usage: https://github.com/grpc/psm-interop#basic-usage
+  local test_suite="${1:?${FUNCNAME[0]} missing the test suite argument}"
+  local test_name="${2:?${FUNCNAME[0]} missing the test name argument}"
+  local out_dir="${TEST_XML_OUTPUT_DIR:-/tmp/psm}/${test_name}"
+  local test_log="${out_dir}/sponge_log.log"
+  mkdir -p "${out_dir}"
+
+  PSM_TEST_FLAGS=(
+    "--flagfile=${TEST_DRIVER_FLAGFILE}"
+    "--kube_context=${KUBE_CONTEXT}"
+    "--force_cleanup"
+    "--collect_app_logs"
+    "--log_dir=${out_dir}"
+    "--xml_output_file=${out_dir}/sponge_log.xml"
+    "--testing_version=${TESTING_VERSION}"
+    "--client_image=${CLIENT_IMAGE_NAME}:${GIT_COMMIT}"
+  )
+
+  # Some test suites have canonical server image configured in the flagfiles.
+  if [[ -z "${SERVER_IMAGE_USE_CANONICAL}" ]]; then
+    PSM_TEST_FLAGS+=("--server_image=${SERVER_IMAGE_NAME}:${GIT_COMMIT}")
+  elif [[ "${GRPC_LANGUAGE}" == "node"  ]]; then
+    # TODO(b/261911148): To be replaced with --server_image_use_canonical when implemented.
+    PSM_TEST_FLAGS+=("--server_image=us-docker.pkg.dev/grpc-testing/psm-interop/java-server:canonical")
+  fi
+
+  # So far, only LB test uses secondary GKE cluster.
+  if [[ -n "${SECONDARY_KUBE_CONTEXT}" ]]; then
+    PSM_TEST_FLAGS+=("--secondary_kube_context=${SECONDARY_KUBE_CONTEXT}")
+  fi
+
+  psm::tools::log "Running ${test_suite} suite test: ${test_name}" |& tee "${test_log}"
+  # Must be the last line.
+  "psm::${test_suite}::run_test" "${test_name}" |& tee -a "${test_log}"
+}
+
+#######################################
+# Appends extra flags (if any) to the end of PSM_TEST_FLAGS, prints the flag list.
+# Globals:
+#   PSM_TEST_FLAGS: The array with flags for the test
+#   PSM_EXTRA_FLAGS: Space-separated string with extra flags to append
+# Arguments:
+#   Test case name
+# Outputs:
+#   Prints the list of test flags to the stdout
+#######################################
+psm::run::finalize_test_flags() {
+  local test_name="${1:?${FUNCNAME[0]} missing the test name argument}"
+
+  # Append extra flags
+  if [[ -n "${PSM_EXTRA_FLAGS}" ]]; then
+    declare -a extra_flags
+    IFS=' ' read -r -a extra_flags <<< "${PSM_EXTRA_FLAGS}"
+    PSM_TEST_FLAGS+=("${extra_flags[@]}")
+  fi
+
+  psm::tools::log "Test driver flags for ${test_name}:"
+  printf -- "%s\n" "${PSM_TEST_FLAGS[@]}"
+  echo
+}
+
+
+# --- Common test setup logic -----------
+
+psm::setup::generic_test_suite() {
+  local test_suite="${1:?${FUNCNAME[0]} missing the test suite argument}"
+  "psm::${test_suite}::setup"
+  psm::setup::test_driver
+  psm::build::docker_images_if_needed
+  psm::setup::get_tests "${test_suite}"
+}
+
+psm::setup::get_tests() {
+  local test_suite="${1:?${FUNCNAME[0]} missing the test suite argument}"
+
+  if [[ -n "${PSM_TESTS}" ]]; then
+    # Test list overridden in env var.
+    IFS=' ' read -r -a TESTS <<< "${PSM_TESTS}"
+    if (( ${#TESTS[@]} == 0 )); then
+        psm::tools::log "Error: test list overridden, but no tests specified"
+        exit 1
+    fi
+  else
+    "psm::${test_suite}::get_tests"
+  fi
+
+  psm::tools::log "Tests in ${test_suite} test suite:"
+  printf -- "  - %s\n" "${TESTS[@]}"
+  echo
+}
+
+#######################################
+# Executes the test case
+# Globals:
+#   CLIENT_IMAGE_NAME: Populated with xDS test client image name
+#   SERVER_IMAGE_NAME: Populated with xDS test server image name
+#   SERVER_IMAGE_USE_CANONICAL: Set to "1" when canonical server image will be used in the tests
+#                               instead of the one configured in SERVER_IMAGE_NAME.
+# Arguments:
+#   gRPC Language
+#   Test case name
+# Outputs:
+#   Writes the output of test execution to stdout, stderr
+#   Test xUnit report to ${TEST_XML_OUTPUT_DIR}/${test_name}/sponge_log.xml
+#######################################
+psm::setup::docker_image_names() {
+  local language="${1:?${FUNCNAME[0]} missing the language argument}"
+  local test_suite="${2:?${FUNCNAME[0]} missing the test suite argument}"
+  SERVER_IMAGE_USE_CANONICAL=""
+
+  case "${language}" in
+    java | cpp | python | go)
+      CLIENT_IMAGE_NAME="${DOCKER_REGISTRY}/grpc-testing/psm-interop/${GRPC_LANGUAGE}-client"
+      SERVER_IMAGE_NAME="${DOCKER_REGISTRY}/grpc-testing/psm-interop/${GRPC_LANGUAGE}-server"
+      ;;
+    node)
+      CLIENT_IMAGE_NAME="${DOCKER_REGISTRY}/grpc-testing/psm-interop/${GRPC_LANGUAGE}-client"
+      SERVER_IMAGE_NAME=""
+      SERVER_IMAGE_USE_CANONICAL="1"
+      ;;
+    *)
+      psm::tools::log "Unknown Language: ${1}"
+      exit 1
+      ;;
+  esac
+
+  case "${test_suite}" in
+    url_map)
+      # Uses the canonical server image configured in url-map.cfg
+      SERVER_IMAGE_USE_CANONICAL="1"
+      ;;
+  esac
+
+  declare -r CLIENT_IMAGE_NAME
+  declare -r SERVER_IMAGE_NAME
+  declare -r SERVER_IMAGE_USE_CANONICAL
+}
+
+psm::setup::test_driver() {
+  local build_docker_script="${BUILD_SCRIPT_DIR}/psm-interop-build-${GRPC_LANGUAGE}.sh"
+  psm::tools::log "Looking for docker image build script ${build_docker_script}"
+  if [[ -f "${build_docker_script}" ]]; then
+    psm::tools::log "Sourcing docker image build script: ${build_docker_script}"
+    source "${build_docker_script}"
+  fi
+
+  if [[ -n "${KOKORO_ARTIFACTS_DIR}" ]]; then
+    kokoro_setup_test_driver "${GITHUB_REPOSITORY_NAME}"
+  else
+    local_setup_test_driver "${BUILD_SCRIPT_DIR}"
+  fi
+}
+
+# --- Common test build logic -----------
+
+#######################################
+# Builds test app and its docker images unless they already exist
+# Globals:
+#   SERVER_IMAGE_NAME: Test server Docker image name
+#   CLIENT_IMAGE_NAME: Test client Docker image name
+#   GIT_COMMIT: SHA-1 of git commit being built
+#   PSM_FORCE_IMAGE_BUILD
+# Arguments:
+#   None
+# Outputs:
+#   Writes the output to stdout, stderr
+#######################################
+psm::build::docker_images_if_needed() {
+  # Check if images already exist
+  client_tags="$(gcloud_gcr_list_image_tags "${CLIENT_IMAGE_NAME}" "${GIT_COMMIT}")"
+  psm::tools::log "Client image: ${CLIENT_IMAGE_NAME}:${GIT_COMMIT}"
+  echo "${client_tags:-Client image not found}"
+
+  if [[ -z "${SERVER_IMAGE_USE_CANONICAL}" ]]; then
+    server_tags="$(gcloud_gcr_list_image_tags "${SERVER_IMAGE_NAME}" "${GIT_COMMIT}")"
+    psm::tools::log "Server image: ${SERVER_IMAGE_NAME}:${GIT_COMMIT}"
+    echo "${server_tags:-Server image not found}"
+  else
+    server_tags="ignored-use-canonical"
+  fi
+
+  # Build if any of the images are missing, or PSM_FORCE_IMAGE_BUILD=1
+  if [[ "${PSM_FORCE_IMAGE_BUILD}" == "1" || -z "${server_tags}" || -z "${client_tags}" ]]; then
+    {
+      psm::tools::log "Building xDS interop test app Docker images"
+      gcloud -q auth configure-docker "${DOCKER_REGISTRY}"
+      psm::lang::build_docker_images
+      psm::tools::log "Finished xDS interop test app Docker images"
+    } | tee -a "${BUILD_LOGS_ROOT}/build-docker.log"
+  else
+    psm::tools::log "Skipping ${GRPC_LANGUAGE} test app build"
+  fi
+}
+
+#######################################
+# Builds test app Docker images and pushes them to GCR
+# Globals:
+#   SRC_DIR: Absolute path to the source repo on Kokoro VM
+#   SERVER_IMAGE_NAME: Test server Docker image name
+#   CLIENT_IMAGE_NAME: Test client Docker image name
+#   GIT_COMMIT: SHA-1 of git commit being built
+#   DOCKER_REGISTRY: Docker registry to push to
+# Arguments:
+#   The path to xDS test client Dockerfile. Can be absolute or relative to SRC_DIR
+#   The path to xDS test server Dockerfile. Optional, server build is skip when omitted.
+# Outputs:
+#   Writes the output of docker image build stdout, stderr
+#######################################
+psm::build::docker_images_generic() {
+  local client_dockerfile="${1:?${FUNCNAME[0]} missing the client dockerfile argument}"
+  local server_dockerfile="${2:-}"
+  pushd "${SRC_DIR}"
+
+  # Client is required.
+  psm::tools::log "Building ${GRPC_LANGUAGE} xDS interop test client"
+  psm::tools::run_verbose docker build -f "${client_dockerfile}" -t "${CLIENT_IMAGE_NAME}:${GIT_COMMIT}" .
+  psm::tools::run_verbose docker push "${CLIENT_IMAGE_NAME}:${GIT_COMMIT}"
+
+  # Server is optional
+  if [[ -n "${server_dockerfile}" ]]; then
+    psm::tools::log "Building ${GRPC_LANGUAGE} xDS interop test server"
+    psm::tools::run_verbose docker build -f "${server_dockerfile}" -t "${SERVER_IMAGE_NAME}:${GIT_COMMIT}" .
+    psm::tools::run_verbose docker push "${SERVER_IMAGE_NAME}:${GIT_COMMIT}"
+  fi
+  popd
+
+  if is_version_branch "${TESTING_VERSION}"; then
+    psm::tools::log "Detected proper version branch ${TESTING_VERSION}, adding version tags."
+    tag_and_push_docker_image "${CLIENT_IMAGE_NAME}" "${GIT_COMMIT}" "${TESTING_VERSION}"
+    if [[ -n "${server_dockerfile}" ]]; then
+      tag_and_push_docker_image "${SERVER_IMAGE_NAME}" "${GIT_COMMIT}" "${TESTING_VERSION}"
+    fi
+  fi
+}
+
+# --- Common helpers ----------------------
+
+#######################################
+# Print the command with its arguments (aka set xtrace/ set -x) before execution.
+# Arguments:
+#   The command to run
+# Returns:
+#   The exit status of the command executed.
+#######################################
+psm::tools::run_verbose() {
+  local exit_code=0
+  set -x
+  "$@" || exit_code=$?
+  { set +x; } 2>/dev/null
+
+  if (( exit_code == 0 )); then
+    psm::tools::log "Cmd finished: ${1}"
+  else
+    psm::tools::log "Cmd failed with exit code ${exit_code}: $*"
+  fi
+
+  return ${exit_code}
+}
+
+#######################################
+# Run command end report its exit code. Doesn't exit on non-zero exit code.
+# Globals:
+#   None
+# Arguments:
+#   Command to execute
+# Outputs:
+#   Writes the output of given command to stdout, stderr
+#######################################
+psm::tools::run_ignore_exit_code() {
+  local exit_code=0
+  "$@" || exit_code=$?
+
+  if (( exit_code == 0 )); then
+    psm::tools::log "Cmd failed with exit code ${exit_code}: $*"
+  fi
+}
+
+psm::tools::log() {
+  echo -en "+ $(date "+[%H:%M:%S %Z]")\011 "
+  echo "$@"
+}
+
+# --- "Unsorted" methods --------------
+# TODO(sergiitk): all methods should be using "psm::" package name,
+#   see https://google.github.io/styleguide/shellguide.html#function-names
 
 #######################################
 # Determines the cluster name and zone based on the given cluster identifier.
@@ -64,11 +648,11 @@ activate_gke_cluster() {
       GKE_CLUSTER_ZONE="us-central1-c"
       ;;
     *)
-      echo "Unknown GKE cluster: ${1}"
+      psm::tools::log "Unknown GKE cluster: ${1}"
       exit 1
       ;;
   esac
-  echo -n "Activated GKE cluster: GKE_CLUSTER_NAME=${GKE_CLUSTER_NAME} "
+  psm::tools::log -n "Activated GKE cluster: GKE_CLUSTER_NAME=${GKE_CLUSTER_NAME} "
   if [[ -n "${GKE_CLUSTER_REGION}" ]]; then
     echo "GKE_CLUSTER_REGION=${GKE_CLUSTER_REGION}"
   else
@@ -94,16 +678,20 @@ activate_secondary_gke_cluster() {
       SECONDARY_GKE_CLUSTER_ZONE="us-west1-b"
       ;;
     *)
-      echo "Unknown secondary GKE cluster: ${1}"
+      psm::tools::log "Unknown secondary GKE cluster: ${1}"
       exit 1
       ;;
   esac
-  echo -n "Activated secondary GKE cluster: SECONDARY_GKE_CLUSTER_NAME=${SECONDARY_GKE_CLUSTER_NAME}"
+  psm::tools::log -n "Activated secondary GKE cluster: SECONDARY_GKE_CLUSTER_NAME=${SECONDARY_GKE_CLUSTER_NAME}"
   echo " SECONDARY_GKE_CLUSTER_ZONE=${SECONDARY_GKE_CLUSTER_ZONE}"
 }
 
 #######################################
 # Run command end report its exit code. Doesn't exit on non-zero exit code.
+#
+# Deprecated. Use psm::tools::run_ignore_exit_code
+# TODO(sergiitk): delete this method when no longer used in per-language buildscripts.
+#
 # Globals:
 #   None
 # Arguments:
@@ -115,7 +703,7 @@ run_ignore_exit_code() {
   local exit_code=0
   "$@" || exit_code=$?
   if [[ $exit_code != 0 ]]; then
-    echo "Cmd: '$*', exit code: ${exit_code}"
+    psm::tools::log "Cmd: '$*', exit code: ${exit_code}"
   fi
 }
 
@@ -220,9 +808,9 @@ gcloud_get_cluster_credentials() {
 #######################################
 test_driver_get_source() {
   if [[ -n "${TEST_DRIVER_REPO_DIR_USE_EXISTING}" && -d "${TEST_DRIVER_REPO_DIR}" ]]; then
-    echo "Using exiting driver directory: ${TEST_DRIVER_REPO_DIR}."
+    psm::tools::log "Using exiting driver directory: ${TEST_DRIVER_REPO_DIR}."
   else
-    echo "Cloning driver to ${TEST_DRIVER_REPO_URL} branch ${TEST_DRIVER_BRANCH} to ${TEST_DRIVER_REPO_DIR}"
+    psm::tools::log "Cloning driver to ${TEST_DRIVER_REPO_URL} branch ${TEST_DRIVER_BRANCH} to ${TEST_DRIVER_REPO_DIR}"
     git clone -b "${TEST_DRIVER_BRANCH}" --depth=1 "${TEST_DRIVER_REPO_URL}" "${TEST_DRIVER_REPO_DIR}"
   fi
 }
@@ -240,16 +828,16 @@ test_driver_get_source() {
 #   Writes the list of installed modules to stdout
 #######################################
 test_driver_pip_install() {
-  echo "Install python dependencies"
+  psm::tools::log "Install python dependencies"
   cd "${TEST_DRIVER_FULL_DIR}"
 
   # Create and activate virtual environment unless already using one
   if [[ -z "${VIRTUAL_ENV}" ]]; then
     local venv_dir="${TEST_DRIVER_FULL_DIR}/venv"
     if [[ -d "${venv_dir}" ]]; then
-      echo "Found python virtual environment directory: ${venv_dir}"
+      psm::tools::log "Found python virtual environment directory: ${venv_dir}"
     else
-      echo "Creating python virtual environment: ${venv_dir}"
+      psm::tools::log "Creating python virtual environment: ${venv_dir}"
       "python${PYTHON_VERSION}" -m venv "${venv_dir}" --upgrade-deps
     fi
     # Intentional: No need to check python venv activate script.
@@ -257,9 +845,14 @@ test_driver_pip_install() {
     source "${venv_dir}/bin/activate"
   fi
 
-  python3 -m pip install -r requirements.lock
-  echo "Installed Python packages:"
-  python3 -m pip list
+  psm::tools::log "Installing Python packages with pip, see install-pip.log"
+  psm::driver::pip_install &>> "${BUILD_LOGS_ROOT}/install-pip.log"
+}
+
+psm::driver::pip_install() {
+  psm::tools::run_verbose python3 -m pip install -r requirements.lock
+  echo
+  psm::tools::run_verbose python3 -m pip list
 }
 
 #######################################
@@ -283,7 +876,7 @@ test_driver_compile_protos() {
     "${TEST_DRIVER_PROTOS_PATH}/messages.proto"
     "${TEST_DRIVER_PROTOS_PATH}/empty.proto"
   )
-  echo "Generate python code from grpc.testing protos: ${protos[*]}"
+  psm::tools::log "Generate python code from grpc.testing protos: ${protos[*]}"
   cd "${TEST_DRIVER_REPO_DIR}"
   python3 -m grpc_tools.protoc \
     --proto_path=. \
@@ -291,13 +884,16 @@ test_driver_compile_protos() {
     --grpc_python_out="${TEST_DRIVER_FULL_DIR}" \
     "${protos[@]}"
   local protos_out_dir="${TEST_DRIVER_FULL_DIR}/${TEST_DRIVER_PROTOS_PATH}"
-  echo "Generated files ${protos_out_dir}:"
-  ls -Fl "${protos_out_dir}"
+
+  if command -v sha256sum &> /dev/null; then
+    psm::tools::log "Generated files ${protos_out_dir}:"
+    find "${protos_out_dir}" -type f -exec sha256sum {} \;
+  fi
 }
 
 #######################################
 # Installs the test driver and it's requirements.
-# https://github.com/grpc/grpc/tree/master/tools/run_tests/xds_k8s_test_driver#installation
+# https://github.com/grpc/psm-interop#basic-usage#installation
 # Globals:
 #   TEST_DRIVER_REPO_DIR: Populated with the path to the repo containing
 #                         the test driver
@@ -323,7 +919,7 @@ test_driver_install() {
 #   Writes the output to stdout
 #######################################
 kokoro_print_version() {
-  echo "Kokoro Ubuntu version:"
+  psm::tools::log "Kokoro Ubuntu version:"
   run_ignore_exit_code lsb_release -a
   run_ignore_exit_code "python${PYTHON_VERSION}" --version
   run_ignore_exit_code "python${PYTHON_VERSION}" -m pip --version
@@ -354,7 +950,7 @@ TESTGRID_EXCLUDE,${TESTGRID_EXCLUDE:-0}
 GIT_ORIGIN_URL,${GIT_ORIGIN_URL:?GIT_ORIGIN_URL must be set}
 GIT_COMMIT_SHORT,${GIT_COMMIT_SHORT:?GIT_COMMIT_SHORT must be set}
 EOF
-  echo "Sponge properties:"
+  psm::tools::log "Sponge properties:"
   cat "${KOKORO_ARTIFACTS_DIR}/custom_sponge_config.csv"
 }
 
@@ -382,7 +978,7 @@ kokoro_install_dependencies() {
 # Globals:
 #   KOKORO_JOB_NAME
 #   KOKORO_BUILD_INITIATOR
-#   FORCE_TESTING_VERSION: Forces the testing version to be something else.
+#   PSM_FORCE_TESTING_VERSION: Forces the testing version to be something else.
 #   TESTING_VERSION: Populated with the version branch under test,
 #                    f.e. master, dev, v1.42.x.
 # Outputs:
@@ -398,10 +994,10 @@ kokoro_get_testing_version() {
   local version_from_job_name
   version_from_job_name=$(echo "${KOKORO_JOB_NAME}" | cut -d '/' -f3)
 
-  if [[ -n "${FORCE_TESTING_VERSION}" ]]; then
+  if [[ -n "${PSM_FORCE_TESTING_VERSION}" ]]; then
     # Allows to override the testing version, and force tagging the built
     # images, if necessary.
-    readonly TESTING_VERSION="${FORCE_TESTING_VERSION}"
+    readonly TESTING_VERSION="${PSM_FORCE_TESTING_VERSION}"
   elif [[ "${KOKORO_BUILD_INITIATOR:-anonymous}" != "kokoro" ]]; then
     # If not initiated by Kokoro, it's a dev branch.
     # This allows to know later down the line that the built image doesn't need
@@ -441,8 +1037,11 @@ kokoro_get_testing_version() {
 #   Writes the output to stdout, stderr, files
 #######################################
 kokoro_setup_test_driver() {
-  # Unset noisy verbose mode often set in the parent script.
+  # Unset noisy verbose mode often set in the parent scripts.
   set +x
+
+  psm::tools::log "Starting Kokoro provisioning"
+
   local src_repository_name="${1:?Usage kokoro_setup_test_driver GITHUB_REPOSITORY_NAME}"
   # Capture Kokoro VM version info in the log.
   kokoro_print_version
@@ -453,11 +1052,22 @@ kokoro_setup_test_driver() {
   # Kokoro clones repo to ${KOKORO_ARTIFACTS_DIR}/github/${GITHUB_REPOSITORY}
   local github_root="${KOKORO_ARTIFACTS_DIR}/github"
   readonly SRC_DIR="${github_root}/${src_repository_name}"
+
+  # Test artifacts dir: xml reports, logs, etc.
+  local artifacts_dir="${KOKORO_ARTIFACTS_DIR}/artifacts"
+  # Folders after $artifacts_dir reported as target name
+  readonly TEST_XML_OUTPUT_DIR="${artifacts_dir}/${KOKORO_JOB_NAME}"
+  readonly BUILD_LOGS_ROOT="${TEST_XML_OUTPUT_DIR}"
+
+  mkdir -p "${artifacts_dir}" "${TEST_XML_OUTPUT_DIR}" "${BUILD_LOGS_ROOT}"
   parse_src_repo_git_info SRC_DIR
   kokoro_write_sponge_properties
-  kokoro_install_dependencies
+
+  psm::tools::log "Installing packages with apt, see install-apt.log"
+  kokoro_install_dependencies &> "${BUILD_LOGS_ROOT}/install-apt.log"
 
   # Get kubectl cluster credentials.
+  psm::tools::log "Fetching GKE cluster credentials"
   gcloud_get_cluster_credentials
 
   # Install the driver.
@@ -466,12 +1076,6 @@ kokoro_setup_test_driver() {
   test_driver_install "${test_driver_repo_dir}"
   # shellcheck disable=SC2034  # Used in the main script
   readonly TEST_DRIVER_FLAGFILE="config/grpc-testing.cfg"
-
-  # Test artifacts dir: xml reports, logs, etc.
-  local artifacts_dir="${KOKORO_ARTIFACTS_DIR}/artifacts"
-  # Folders after $artifacts_dir reported as target name
-  readonly TEST_XML_OUTPUT_DIR="${artifacts_dir}/${KOKORO_JOB_NAME}"
-  mkdir -p "${artifacts_dir}" "${TEST_XML_OUTPUT_DIR}"
 }
 
 #######################################
@@ -501,8 +1105,8 @@ local_setup_test_driver() {
   readonly SECONDARY_KUBE_CONTEXT="${SECONDARY_KUBE_CONTEXT}"
 
   # Never override docker image for local runs, unless explicitly forced.
-  if [[ -n "${FORCE_TESTING_VERSION}" ]]; then
-    readonly TESTING_VERSION="${FORCE_TESTING_VERSION}"
+  if [[ -n "${PSM_FORCE_TESTING_VERSION}" ]]; then
+    readonly TESTING_VERSION="${PSM_FORCE_TESTING_VERSION}"
   else
     readonly TESTING_VERSION="dev"
   fi
@@ -515,7 +1119,8 @@ local_setup_test_driver() {
   readonly TEST_DRIVER_FLAGFILE="config/local-dev.cfg"
   # Test out
   readonly TEST_XML_OUTPUT_DIR="${TEST_DRIVER_FULL_DIR}/out"
-  mkdir -p "${TEST_XML_OUTPUT_DIR}"
+  readonly BUILD_LOGS_ROOT="${TEST_XML_OUTPUT_DIR}"
+  mkdir -p "${TEST_XML_OUTPUT_DIR}" "${BUILD_LOGS_ROOT}"
 }
 
 #######################################
@@ -532,6 +1137,6 @@ tag_and_push_docker_image() {
   local from_tag="$2"
   local to_tag="$3"
 
-  docker tag "${image_name}:${from_tag}" "${image_name}:${to_tag}"
-  docker push "${image_name}:${to_tag}"
+  psm::tools::run_verbose docker tag "${image_name}:${from_tag}" "${image_name}:${to_tag}"
+  psm::tools::run_verbose push "${image_name}:${to_tag}"
 }
diff --git a/framework/infrastructure/gcp/api.py b/framework/infrastructure/gcp/api.py
index cee8af19..a539b1eb 100644
--- a/framework/infrastructure/gcp/api.py
+++ b/framework/infrastructure/gcp/api.py
@@ -126,13 +126,14 @@ def private_api_key(self):
         return secret.payload.data.decode()
 
     @functools.lru_cache(None)
-    def compute(self, version):
+    def compute(self, version: str):
         api_name = "compute"
+
+        if version.startswith("v1") and self.compute_v1_discovery_file:
+            return self._build_from_file(self.compute_v1_discovery_file)
+
         if version == "v1":
-            if self.compute_v1_discovery_file:
-                return self._build_from_file(self.compute_v1_discovery_file)
-            else:
-                return self._build_from_discovery_v1(api_name, version)
+            return self._build_from_discovery_v1(api_name, version)
         elif version == "v1alpha":
             return self._build_from_discovery_v1(api_name, "alpha")
 
diff --git a/tests/subsetting_test.py b/tests/subsetting_test.py
index 8231b609..ca5421f8 100644
--- a/tests/subsetting_test.py
+++ b/tests/subsetting_test.py
@@ -23,6 +23,10 @@
 from framework.helpers import skips
 
 flags.adopt_module_key_flags(xds_k8s_testcase)
+# Change the default value of --compute_api_version to v1alpha.
+# Subsetting test requires Compute v1alpha APIs.
+# Can be tested with another API version if the flag is passed to the test.
+flags.set_default(xds_k8s_testcase.xds_flags.COMPUTE_API_VERSION, "v1alpha")
 
 # Type aliases
 _XdsTestServer = xds_k8s_testcase.XdsTestServer