SERVER-107805 Add option to not download c++ toolchain for faster python builds (#39355)

GitOrigin-RevId: a2d449d33df132abb0d6086bcd7f600f5708bb58

bazel/toolchains/cc/mongo_linux/mongo_toolchain.bzl

@@ -2,9 +2,17 @@ load("//bazel:utils.bzl", "generate_noop_toolchain", "get_toolchain_subs", "retr
 load("//bazel/toolchains/cc/mongo_linux:mongo_toolchain_version.bzl", "TOOLCHAIN_MAP")
 load("//bazel/toolchains/cc/mongo_linux:mongo_mold.bzl", "MOLD_MAP")
 
+SKIP_TOOLCHAIN_ENVIRONMENT_VARIABLE = "no_c++_toolchain"
+
 def _toolchain_download(ctx):
     distro, arch, substitutions = get_toolchain_subs(ctx)
 
+    skip_toolchain = ctx.os.environ.get(SKIP_TOOLCHAIN_ENVIRONMENT_VARIABLE, None)
+    if skip_toolchain:
+        generate_noop_toolchain(ctx, substitutions)
+        print("Skipping c++ toolchain download and defining noop toolchain due to " + SKIP_TOOLCHAIN_ENVIRONMENT_VARIABLE + " being defined.")
+        return None
+
     toolchain_key = "{distro}_{arch}".format(distro = distro, arch = arch)
 
     if toolchain_key in TOOLCHAIN_MAP[ctx.attr.version]:
@@ -50,6 +58,7 @@ def _toolchain_download(ctx):
 
 toolchain_download = repository_rule(
     implementation = _toolchain_download,
+    environ = [SKIP_TOOLCHAIN_ENVIRONMENT_VARIABLE],
     attrs = {
         "os": attr.string(
             values = ["macos", "linux", "windows"],

bazel/wrapper_hook/install_modules.py

@@ -88,8 +88,12 @@ def search_for_modules(deps, deps_installed, lockfile_changed=False):
     wrapper_debug(f"deps_not_found: {deps_not_found}")
     return deps_not_found
 
+def skip_cplusplus_toolchain(args):
+    if any("no_c++_toolchain" in arg for arg in args):
+        return True
+    return False
 
-def install_modules(bazel):
+def install_modules(bazel, args):
     need_to_install = False
     pwd_hash = hashlib.md5(str(REPO_ROOT).encode()).hexdigest()
     lockfile_hash_file = pathlib.Path(tempfile.gettempdir()) / f"{pwd_hash}_lockfile_hash"
@@ -123,6 +127,10 @@ def install_modules(bazel):
             bazel,
             "build",
         ] + ["@poetry//:library_" + dep.replace("-", "_") for dep in deps_needed]
+
+        if skip_cplusplus_toolchain(args):
+            cmd += ["--repo_env=no_c++_toolchain=1"]
+
         proc = subprocess.run(
             cmd
             + [

bazel/wrapper_hook/post_bazel_hook.py

@@ -13,7 +13,7 @@ BAZEL_CI_NAMESPACE = "ci-prod"
 
 
 def main():
-    install_modules(sys.argv[1])
+    install_modules(sys.argv[1], sys.argv[1:])
 
     from bazel.wrapper_hook.flag_sync import sync_flags
 

bazel/wrapper_hook/wrapper_hook.py

@@ -16,7 +16,7 @@ wrapper_debug(f"wrapper hook script is using {sys.executable}")
 
 
 def main():
-    install_modules(sys.argv[1])
+    install_modules(sys.argv[1], sys.argv[1:])
 
     from bazel.wrapper_hook.autogenerated_targets import autogenerate_targets
     from bazel.wrapper_hook.engflow_check import engflow_auth