Deprecate the command line interface.

.github/workflows/main.yml

@@ -29,7 +29,7 @@ jobs:
       run: |
         mkdir build
         cd build
-        cmake .. -DGOOGLE_TEST=ON -DUSE_OPENMP=ON -DUSE_DMLC_GTEST=ON -DPLUGIN_DENSE_PARSER=ON -GNinja
+        cmake .. -DGOOGLE_TEST=ON -DUSE_OPENMP=ON -DUSE_DMLC_GTEST=ON -DPLUGIN_DENSE_PARSER=ON -GNinja -DBUILD_DEPRECATED_CLI=ON
         ninja -v
     - name: Run gtest binary
       run: |
@@ -56,7 +56,7 @@ jobs:
       run: |
         mkdir build
         cd build
-        cmake .. -GNinja -DGOOGLE_TEST=ON  -DUSE_DMLC_GTEST=ON -DUSE_OPENMP=OFF
+        cmake .. -GNinja -DGOOGLE_TEST=ON  -DUSE_DMLC_GTEST=ON -DUSE_OPENMP=OFF -DBUILD_DEPRECATED_CLI=ON
         ninja -v
     - name: Run gtest binary
       run: |

.github/workflows/python_tests.yml

@@ -143,7 +143,7 @@ jobs:
         # Set prefix, to use OpenMP library from Conda env
         # See https://github.com/dmlc/xgboost/issues/7039#issuecomment-1025038228
         # to learn why we don't use libomp from Homebrew.
-        cmake .. -GNinja -DCMAKE_PREFIX_PATH=$CONDA_PREFIX
+        cmake .. -GNinja -DCMAKE_PREFIX_PATH=$CONDA_PREFIX -DBUILD_DEPRECATED_CLI=ON
         ninja
 
     - name: Install Python package
@@ -190,7 +190,7 @@ jobs:
       run: |
         mkdir build_msvc
         cd build_msvc
-        cmake .. -G"Visual Studio 17 2022" -DCMAKE_CONFIGURATION_TYPES="Release" -A x64 -DGOOGLE_TEST=ON  -DUSE_DMLC_GTEST=ON
+        cmake .. -G"Visual Studio 17 2022" -DCMAKE_CONFIGURATION_TYPES="Release" -A x64 -DGOOGLE_TEST=ON  -DUSE_DMLC_GTEST=ON -DBUILD_DEPRECATED_CLI=ON
         cmake --build . --config Release --parallel $(nproc)
 
     - name: Install Python package
@@ -234,7 +234,7 @@ jobs:
       run: |
         mkdir build
         cd build
-        cmake .. -GNinja -DCMAKE_PREFIX_PATH=$CONDA_PREFIX
+        cmake .. -GNinja -DCMAKE_PREFIX_PATH=$CONDA_PREFIX -DBUILD_DEPRECATED_CLI=ON
         ninja
 
     - name: Install Python package

CMakeLists.txt

@@ -45,6 +45,7 @@ set_default_configuration_release()
 option(BUILD_C_DOC "Build documentation for C APIs using Doxygen." OFF)
 option(USE_OPENMP "Build with OpenMP support." ON)
 option(BUILD_STATIC_LIB "Build static library" OFF)
+option(BUILD_DEPRECATED_CLI "Build the deprecated command line interface" OFF)
 option(FORCE_SHARED_CRT "Build with dynamic CRT on Windows (/MD)" OFF)
 option(RABIT_BUILD_MPI "Build MPI" OFF)
 ## Bindings
@@ -273,19 +274,30 @@ target_include_directories(xgboost
 #-- End shared library
 
 #-- CLI for xgboost
-add_executable(runxgboost ${xgboost_SOURCE_DIR}/src/cli_main.cc)
-target_link_libraries(runxgboost PRIVATE objxgboost)
-target_include_directories(runxgboost
-  PRIVATE
-  ${xgboost_SOURCE_DIR}/include
-  ${xgboost_SOURCE_DIR}/dmlc-core/include
-  ${xgboost_SOURCE_DIR}/rabit/include
-)
-set_target_properties(runxgboost PROPERTIES OUTPUT_NAME xgboost)
+if (BUILD_DEPRECATED_CLI)
+  add_executable(runxgboost ${xgboost_SOURCE_DIR}/src/cli_main.cc)
+  target_link_libraries(runxgboost PRIVATE objxgboost)
+  target_include_directories(runxgboost
+    PRIVATE
+    ${xgboost_SOURCE_DIR}/include
+    ${xgboost_SOURCE_DIR}/dmlc-core/include
+    ${xgboost_SOURCE_DIR}/rabit/include
+  )
+  set_target_properties(runxgboost PROPERTIES OUTPUT_NAME xgboost)
+  xgboost_target_properties(runxgboost)
+  xgboost_target_link_libraries(runxgboost)
+  xgboost_target_defs(runxgboost)
+
+  if (KEEP_BUILD_ARTIFACTS_IN_BINARY_DIR)
+    set_output_directory(runxgboost ${xgboost_BINARY_DIR})
+  else ()
+    set_output_directory(runxgboost ${xgboost_SOURCE_DIR})
+  endif (KEEP_BUILD_ARTIFACTS_IN_BINARY_DIR)
+endif (BUILD_DEPRECATED_CLI)
 #-- End CLI for xgboost
 
 # Common setup for all targets
-foreach(target xgboost objxgboost dmlc runxgboost)
+foreach(target xgboost objxgboost dmlc)
   xgboost_target_properties(${target})
   xgboost_target_link_libraries(${target})
   xgboost_target_defs(${target})
@@ -298,14 +310,15 @@ if (JVM_BINDINGS)
 endif (JVM_BINDINGS)
 
 if (KEEP_BUILD_ARTIFACTS_IN_BINARY_DIR)
-  set_output_directory(runxgboost ${xgboost_BINARY_DIR})
   set_output_directory(xgboost ${xgboost_BINARY_DIR}/lib)
 else ()
-  set_output_directory(runxgboost ${xgboost_SOURCE_DIR})
   set_output_directory(xgboost ${xgboost_SOURCE_DIR}/lib)
 endif ()
+
 # Ensure these two targets do not build simultaneously, as they produce outputs with conflicting names
-add_dependencies(xgboost runxgboost)
+if (BUILD_DEPRECATED_CLI)
+  add_dependencies(xgboost runxgboost)
+endif (BUILD_DEPRECATED_CLI)
 
 #-- Installing XGBoost
 if (R_LIB)
@@ -341,9 +354,17 @@ install(DIRECTORY ${xgboost_SOURCE_DIR}/include/xgboost
 #
 # https://github.com/dmlc/xgboost/issues/6085
 if (BUILD_STATIC_LIB)
-  set(INSTALL_TARGETS xgboost runxgboost objxgboost dmlc)
+  if (BUILD_DEPRECATED_CLI)
+    set(INSTALL_TARGETS xgboost runxgboost objxgboost dmlc)
+  else()
+    set(INSTALL_TARGETS xgboost objxgboost dmlc)
+  endif (BUILD_DEPRECATED_CLI)
 else (BUILD_STATIC_LIB)
-  set(INSTALL_TARGETS xgboost runxgboost)
+  if (BUILD_DEPRECATED_CLI)
+    set(INSTALL_TARGETS xgboost runxgboost)
+  else(BUILD_DEPRECATED_CLI)
+    set(INSTALL_TARGETS xgboost)
+  endif (BUILD_DEPRECATED_CLI)
 endif (BUILD_STATIC_LIB)
 
 install(TARGETS ${INSTALL_TARGETS}
@@ -393,13 +414,15 @@ if (GOOGLE_TEST)
     ${xgboost_SOURCE_DIR}/tests/cli/machine.conf.in
     ${xgboost_BINARY_DIR}/tests/cli/machine.conf
     @ONLY)
-  add_test(
-    NAME TestXGBoostCLI
-    COMMAND runxgboost ${xgboost_BINARY_DIR}/tests/cli/machine.conf
-    WORKING_DIRECTORY ${xgboost_BINARY_DIR})
-  set_tests_properties(TestXGBoostCLI
-    PROPERTIES
-    PASS_REGULAR_EXPRESSION ".*test-rmse:0.087.*")
+  if (BUILD_DEPRECATED_CLI)
+    add_test(
+      NAME TestXGBoostCLI
+      COMMAND runxgboost ${xgboost_BINARY_DIR}/tests/cli/machine.conf
+      WORKING_DIRECTORY ${xgboost_BINARY_DIR})
+    set_tests_properties(TestXGBoostCLI
+      PROPERTIES
+      PASS_REGULAR_EXPRESSION ".*test-rmse:0.087.*")
+  endif (BUILD_DEPRECATED_CLI)
 endif (GOOGLE_TEST)
 
 # For MSVC: Call msvc_use_static_runtime() once again to completely

demo/CLI/README.rst

@@ -0,0 +1,4 @@
+XGBoost Command Line Interface Walkthrough
+==========================================
+
+Please note that the command line interface is deprecated in 2.1.0, use other language bindings instead. For a list of available bindings, see https://xgboost.readthedocs.io/en/stable/

src/cli_main.cc

@@ -514,7 +514,9 @@ class CLI {
 };
 }  // namespace xgboost
 
-int main(int argc, char *argv[]) {
+int main(int argc, char* argv[]) {
+  LOG(WARNING)
+      << "The command line interface is deprecated and will be removed in future releases.";
   try {
     xgboost::CLI cli(argc, argv);
     return cli.Run();

tests/buildkite/build-win64-gpu.ps1

@@ -13,7 +13,7 @@ if ( $is_release_branch -eq 0 ) {
 mkdir build
 cd build
 cmake .. -G"Visual Studio 17 2022" -A x64 -DUSE_CUDA=ON -DCMAKE_VERBOSE_MAKEFILE=ON `
-  -DGOOGLE_TEST=ON -DUSE_DMLC_GTEST=ON ${arch_flag}
+  -DGOOGLE_TEST=ON -DUSE_DMLC_GTEST=ON -DBUILD_DEPRECATED_CLI=ON ${arch_flag}
 $msbuild = -join @(
   "C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\MSBuild\\Current"
   "\\Bin\\MSBuild.exe"

tests/ci_build/build_r_pkg_with_cuda.sh

@@ -19,7 +19,6 @@ cmake .. -GNinja -DUSE_CUDA=ON -DR_LIB=ON
 ninja
 cd ..
 
-rm xgboost
 # This super wacky hack is found in cmake/RPackageInstall.cmake.in and
 # cmake/RPackageInstallTargetSetup.cmake. This hack lets us bypass the normal build process of R
 # and have R use xgboost.so that we've already built.

tests/ci_build/build_r_pkg_with_cuda_win64.sh

@@ -22,7 +22,6 @@ cmake .. -G"Visual Studio 17 2022" -A x64 -DUSE_CUDA=ON -DR_LIB=ON -DLIBR_HOME="
 cmake --build . --config Release --parallel
 cd ..
 
-rm xgboost
 # This super wacky hack is found in cmake/RPackageInstall.cmake.in and
 # cmake/RPackageInstallTargetSetup.cmake. This hack lets us bypass the normal build process of R
 # and have R use xgboost.dll that we've already built.

tests/ci_build/build_via_cmake.sh

@@ -24,7 +24,7 @@ fi
 rm -rf build
 mkdir build
 cd build
-cmake .. ${cmake_args} -DGOOGLE_TEST=ON -DUSE_DMLC_GTEST=ON -DCMAKE_VERBOSE_MAKEFILE=ON -DENABLE_ALL_WARNINGS=ON -DCMAKE_COMPILE_WARNING_AS_ERROR=ON -GNinja ${cmake_prefix_flag} -DHIDE_CXX_SYMBOLS=ON
+cmake .. ${cmake_args} -DGOOGLE_TEST=ON -DUSE_DMLC_GTEST=ON -DCMAKE_VERBOSE_MAKEFILE=ON -DENABLE_ALL_WARNINGS=ON -DCMAKE_COMPILE_WARNING_AS_ERROR=ON -GNinja ${cmake_prefix_flag} -DHIDE_CXX_SYMBOLS=ON -DBUILD_DEPRECATED_CLI=ON
 ninja clean
 time ninja -v
 cd ..