ci: configure a CMake+Ninja build (#1229)

Ninja is more strict than Make, building with it can detect bugs in our
CMake files. And while Ninja is not as well-known as Make, it is a
faster builder, and therefore it is somewhat popular as a CMake backend.

Author: coryan

ci/kokoro/docker/build-in-docker-cmake.sh

@@ -64,11 +64,21 @@ if [[ "${GOOGLE_CLOUD_CPP_CXX_STANDARD:-}" != "" ]]; then
   cmake_flags+=(
     "-DGOOGLE_CLOUD_CPP_CXX_STANDARD=${GOOGLE_CLOUD_CPP_CXX_STANDARD}")
 fi
+if [[ "${USE_NINJA:-}" == "yes" ]]; then
+  cmake_flags+=( "-GNinja" )
+fi
 
 # We disable the shellcheck warning because we want ${CMAKE_FLAGS} to expand as
 # separate arguments.
+echo "================================================================"
+echo "Running CMake configuration step $(date)."
+echo "    cmake ${CMAKE_FLAGS:-} -H${SOURCE_DIR} -B${BINARY_DIR}" "${cmake_flags[@]}"
 # shellcheck disable=SC2086
 cmake ${CMAKE_FLAGS:-} "-H${SOURCE_DIR}" "-B${BINARY_DIR}" "${cmake_flags[@]}"
+
+echo "================================================================"
+echo "Running CMake build step $(date)."
+echo "    cmake" --build "${BINARY_DIR}" -- -j "$(nproc)"
 cmake --build "${BINARY_DIR}" -- -j "$(nproc)"
 
 TEST_JOB_COUNT="$(nproc)"

ci/kokoro/docker/build.sh

@@ -136,6 +136,12 @@ elif [[ "${BUILD_NAME}" = "cmake-super" ]]; then
   export BUILD_TYPE=Release
   export CMAKE_FLAGS=-DBUILD_SHARED_LIBS=yes
   in_docker_script="ci/kokoro/docker/build-in-docker-cmake.sh"
+elif [[ "${BUILD_NAME}" = "ninja" ]]; then
+  # Compiling with Ninja can catch bugs that may not be caught using Make.
+  export USE_NINJA=yes
+  export CMAKE_SOURCE_DIR="super"
+  export CMAKE_FLAGS=-DBUILD_SHARED_LIBS=yes
+  in_docker_script="ci/kokoro/docker/build-in-docker-cmake.sh"
 elif [[ "${BUILD_NAME}" = "gcc-4.8" ]]; then
   # The oldest version of GCC we support is 4.8, this build checks the code
   # against that version. The use of CentOS 7 for that build is not a
@@ -298,6 +304,9 @@ docker_flags=(
     # Additional flags to enable CMake features.
     "--env" "CMAKE_FLAGS=${CMAKE_FLAGS:-}"
 
+    # If set, enable the Ninja generator with CMake.
+    "--env" "USE_NINJA=${USE_NINJA:-}"
+
     # If set, run the check-api.sh script.
     "--env" "CHECK_API=${CHECK_API:-}"