53 lines
1.9 KiB
Python
53 lines
1.9 KiB
Python
"""PySpark SQL Guardrails — validator and safe execution wrapper.
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This module is the canonical implementation referenced by
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.claude/skills/pyspark-sql-guardrails/SKILL.md. Do not redefine the
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regex inline at call sites; do not write "lighter" versions. Always
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import this module and route `spark.sql(...)` through `safe_spark_sql`.
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The validator is pure-Python and has no Spark / I/O dependencies. It
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is safe to import in unit tests, CI, notebooks, and ad-hoc scripts.
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"""
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import re
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_FORBIDDEN_SQL = re.compile(
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r"\b(delete|truncate|drop|alter|create|replace|merge|update|msck|refresh|analyze|cache|uncache|vacuum|optimize)\b",
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re.IGNORECASE,
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)
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_LEADING_COMMENTS = re.compile(r"\A\s*(?:--[^\n]*\n|/\*.*?\*/\s*)*", re.DOTALL)
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def assert_select_or_insert(sql: str) -> str:
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"""Return the SQL body if it is a single SELECT/INSERT, else raise ValueError.
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Hard-allowlist. No I/O, no logging side effects, no Spark dependency.
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Safe to call in unit tests, CI, notebooks, and ad-hoc scripts.
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"""
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text = sql.strip()
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if not text:
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raise ValueError("SQL is empty")
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body = text[:-1].strip() if text.endswith(";") else text
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if ";" in body:
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raise ValueError("Multiple SQL statements are not allowed")
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normalized = _LEADING_COMMENTS.sub("", body).lstrip()
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first = normalized.split(None, 1)[0].lower() if normalized else ""
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if first not in {"select", "with", "insert"}:
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raise ValueError(f"Only SELECT and INSERT SQL are allowed, got {first!r}")
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if _FORBIDDEN_SQL.search(normalized):
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raise ValueError("Forbidden SQL keyword found")
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if first == "with" and not re.search(r"\bselect\b", normalized, re.IGNORECASE):
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raise ValueError("WITH statements must be SELECT queries")
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return body
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def safe_spark_sql(spark, sql: str):
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"""Validate then execute. The ONLY sanctioned path to spark.sql()."""
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return spark.sql(assert_select_or_insert(sql))
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