[cmake] Use Bazelisk to download Bazel

CMakeLists.txt

@@ -104,11 +104,6 @@ else()
     "tools/ubuntu-${UNIX_DISTRIBUTION_CODENAME}.bazelrc")
 endif()
 
-# The version passed to find_package(Bazel) should match the
-# minimum_bazel_version value in the call to versions.check() in WORKSPACE.
-set(MINIMUM_BAZEL_VERSION 4.0)
-find_package(Bazel ${MINIMUM_BAZEL_VERSION} MODULE REQUIRED)
-
 get_filename_component(C_COMPILER_REALPATH "${CMAKE_C_COMPILER}" REALPATH)
 get_filename_component(C_COMPILER_NAME "${C_COMPILER_REALPATH}" NAME)
 
@@ -581,22 +576,26 @@ endforeach()
 # name `drake_build_cwd` isn't important, it just needs to be unique.
 configure_file(cmake/bazel.rc.in drake_build_cwd/.bazelrc @ONLY)
 configure_file(cmake/WORKSPACE.in drake_build_cwd/WORKSPACE.bazel @ONLY)
+file(CREATE_LINK "${PROJECT_SOURCE_DIR}/.bazeliskrc" drake_build_cwd/.bazeliskrc SYMBOLIC)
 
 include(ExternalProject)
 
 ExternalProject_Add(drake_cxx_python
   SOURCE_DIR "${PROJECT_SOURCE_DIR}"
   BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/drake_build_cwd"
   CONFIGURE_COMMAND
-    "${Bazel_EXECUTABLE}"
+    "${Python_EXECUTABLE}"
+    "${PROJECT_SOURCE_DIR}/third_party/com_github_bazelbuild_bazelisk/bazelisk.py"
     info --announce_rc
   BUILD_COMMAND
-    "${Bazel_EXECUTABLE}"
+    "${Python_EXECUTABLE}"
+    "${PROJECT_SOURCE_DIR}/third_party/com_github_bazelbuild_bazelisk/bazelisk.py"
     build
     ${BAZEL_INSTALL_TARGET}
   BUILD_ALWAYS ON
   INSTALL_COMMAND
-    "${Bazel_EXECUTABLE}"
+    "${Python_EXECUTABLE}"
+    "${PROJECT_SOURCE_DIR}/third_party/com_github_bazelbuild_bazelisk/bazelisk.py"
     run
     ${BAZEL_INSTALL_TARGET}
     --

WORKSPACE

@@ -15,6 +15,5 @@ drake_clion_environment()
 load("@bazel_skylib//lib:versions.bzl", "versions")
 
 # This needs to be in WORKSPACE or a repository rule for native.bazel_version
-# to actually be defined. The minimum_bazel_version value should match the
-# version passed to the find_package(Bazel) call in the root CMakeLists.txt.
+# to actually be defined.
 versions.check(minimum_bazel_version = "4.0")

setup/mac/source_distribution/install_prereqs_user_environment.sh

@@ -22,3 +22,6 @@ cat > "${bazelrc}" <<EOF
 import %workspace%/tools/macos.bazelrc
 import %workspace%/tools/macos-arch-${arch}.bazelrc
 EOF
+
+# Prefetch the bazelisk download of bazel.
+(cd "${workspace_dir}" && bazelisk version) > /dev/null

setup/ubuntu/source_distribution/install_prereqs_user_environment.sh

@@ -21,3 +21,6 @@ cat > "${bazelrc}" <<EOF
 import %workspace%/tools/ubuntu.bazelrc
 import %workspace%/tools/ubuntu-${codename}.bazelrc
 EOF
+
+# Prefetch the bazelisk download of bazel.
+(cd "${workspace_dir}" && ./third_party/com_github_bazelbuild_bazelisk/bazelisk.py version) > /dev/null