adding pre commit hook (#1206)

Signed-off-by: Paige Patton <prubenda@redhat.com>

.pre-commit-config.yaml

@@ -0,0 +1,9 @@
+repos:
+  - repo: local
+    hooks:
+      - id: check-license-header
+        name: Check Apache 2.0 license header
+        language: python
+        entry: python scripts/check_license.py
+        types: [python]
+        exclude: ^tests/|/test_|CI/

scripts/check_license.py

@@ -0,0 +1,108 @@
+#!/usr/bin/env python3
+"""
+License header linter for krkn source files.
+
+Checks that all non-test Python source files contain the Apache 2.0 license header.
+Test files (in tests/ or named test_*.py) are excluded.
+
+Usage:
+    # Check only (exit 1 if any files are missing the header)
+    python scripts/check_license.py
+
+    # Auto-fix: prepend header to files that are missing it
+    python scripts/check_license.py --fix
+
+    # Check specific files (e.g. from pre-commit)
+    python scripts/check_license.py path/to/file.py [...]
+"""
+
+import argparse
+import sys
+from pathlib import Path
+
+LICENSE_HEADER = """\
+# Copyright 2025 The Krkn Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License."""
+
+# Check for the copyright line only — allows year/author variation
+LICENSE_MARKER = "# Copyright 2025 The Krkn Authors"
+
+REPO_ROOT = Path(__file__).parent.parent
+
+
+def is_test_file(path: Path) -> bool:
+    parts = path.parts
+    return "tests" in parts or path.name.startswith("test_")
+
+
+def collect_source_files() -> list[Path]:
+    return [
+        p
+        for p in REPO_ROOT.rglob("*.py")
+        if not is_test_file(p)
+        and not any(part.startswith(".") or part in ("venv", "venv3111", "build", "dist", "__pycache__") for part in p.parts)
+    ]
+
+
+def has_license(path: Path) -> bool:
+    try:
+        content = path.read_text(encoding="utf-8")
+        return LICENSE_MARKER in content
+    except (OSError, UnicodeDecodeError):
+        return True  # skip unreadable files silently
+
+
+def add_license(path: Path) -> None:
+    content = path.read_text(encoding="utf-8")
+    # Preserve shebang on the first line if present
+    if content.startswith("#!"):
+        shebang, rest = content.split("\n", 1)
+        path.write_text(f"{shebang}\n{LICENSE_HEADER}\n{rest}", encoding="utf-8")
+    else:
+        path.write_text(f"{LICENSE_HEADER}\n{content}", encoding="utf-8")
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="Check/add Apache 2.0 license headers")
+    parser.add_argument("files", nargs="*", help="Files to check (defaults to all source files)")
+    parser.add_argument("--fix", action="store_true", help="Prepend license header to files missing it")
+    args = parser.parse_args()
+
+    if args.files:
+        paths = [Path(f) for f in args.files if not is_test_file(Path(f)) and f.endswith(".py")]
+    else:
+        paths = collect_source_files()
+
+    missing = [p for p in paths if not has_license(p)]
+
+    if not missing:
+        print("All files have the license header.")
+        return 0
+
+    if args.fix:
+        for p in missing:
+            add_license(p)
+            print(f"  fixed: {p.relative_to(REPO_ROOT)}")
+        print(f"\nAdded license header to {len(missing)} file(s).")
+        return 0
+
+    print("Missing license header in the following files:")
+    for p in missing:
+        print(f"  {p.relative_to(REPO_ROOT)}")
+    print(f"\nRun with --fix to add the header automatically.")
+    return 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())