[MISC][pre-commit] Add pre-commit check for triton import (#17716)

Signed-off-by: Mengqing Cao <cmq0113@163.com>

.pre-commit-config.yaml

@@ -128,6 +128,13 @@ repos:
     name: Update Dockerfile dependency graph
     entry: tools/update-dockerfile-graph.sh
     language: script
+  # forbid directly import triton
+  - id: forbid-direct-triton-import
+    name: "Forbid direct 'import triton'"
+    entry: python tools/check_triton_import.py
+    language: python
+    types: [python]
+    pass_filenames: false
   # Keep `suggestion` last
   - id: suggestion
     name: Suggestion

tools/check_triton_import.py

+# SPDX-License-Identifier: Apache-2.0
+import re
+import subprocess
+import sys
+
+FORBIDDEN_IMPORT_RE = re.compile(r"^(from|import)\s+triton(\s|\.|$)")
+
+# the way allowed to import triton
+ALLOWED_LINES = {
+    "from vllm.triton_utils import triton",
+    "from vllm.triton_utils import tl",
+    "from vllm.triton_utils import tl, triton",
+}
+
+
+def is_forbidden_import(line: str) -> bool:
+    stripped = line.strip()
+    return bool(
+        FORBIDDEN_IMPORT_RE.match(stripped)) and stripped not in ALLOWED_LINES
+
+
+def parse_diff(diff: str) -> list[str]:
+    violations = []
+    current_file = None
+    current_lineno = None
+
+    for line in diff.splitlines():
+        if line.startswith("+++ b/"):
+            current_file = line[6:]
+        elif line.startswith("@@"):
+            match = re.search(r"\+(\d+)", line)
+            if match:
+                current_lineno = int(
+                    match.group(1)) - 1  # next "+ line" is here
+        elif line.startswith("+") and not line.startswith("++"):
+            current_lineno += 1
+            code_line = line[1:]
+            if is_forbidden_import(code_line):
+                violations.append(
+                    f"{current_file}:{current_lineno}: {code_line.strip()}")
+    return violations
+
+
+def get_diff(diff_type: str) -> str:
+    if diff_type == "staged":
+        return subprocess.check_output(
+            ["git", "diff", "--cached", "--unified=0"], text=True)
+    elif diff_type == "unstaged":
+        return subprocess.check_output(["git", "diff", "--unified=0"],
+                                       text=True)
+    else:
+        raise ValueError(f"Unknown diff_type: {diff_type}")
+
+
+def main():
+    all_violations = []
+    for diff_type in ["staged", "unstaged"]:
+        try:
+            diff_output = get_diff(diff_type)
+            violations = parse_diff(diff_output)
+            all_violations.extend(violations)
+        except subprocess.CalledProcessError as e:
+            print(f"[{diff_type}] Git diff failed: {e}", file=sys.stderr)
+
+    if all_violations:
+        print("❌ Forbidden direct `import triton` detected."
+              " ➤ Use `from vllm.triton_utils import triton` instead.\n")
+        for v in all_violations:
+            print(f"❌ {v}")
+        return 1
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())