102 lines
3.2 KiB
Python
102 lines
3.2 KiB
Python
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"""The databases.csv contract: its columns, its delimiter, and what a row means.
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``baudolo-seed`` writes the file, the backup reads it to learn which dumps to
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take, and a restore consumer reads it again to replay them. Stating the schema
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once keeps a column or a convention added here from being invisible to the
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other two.
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Field values are handed back exactly as they stand in the file. A password may
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legitimately begin or end with a space, so stripping belongs to the caller that
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compares, never to the reader.
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"""
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from __future__ import annotations
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import csv
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import re
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from typing import NamedTuple
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COLUMNS = ("instance", "database", "username", "password")
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DELIMITER = ";"
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CLUSTER_ROW = "*"
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_NAME_RE = re.compile(r"^[a-zA-Z0-9_][a-zA-Z0-9_-]*$")
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class DatabasesCsvError(ValueError):
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"""A row does not match the contract."""
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class Row(NamedTuple):
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"""One databases.csv row, verbatim.
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``database`` holds :data:`CLUSTER_ROW` when the whole instance is dumped.
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"""
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instance: str
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database: str
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username: str
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password: str
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@property
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def is_cluster(self) -> bool:
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return self.database.strip() == CLUSTER_ROW
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def validate_database(value: str | None, *, instance: str) -> str:
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"""The database column of one row, or raise.
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The name reaches a shell as part of the dump command, so it is checked
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where it is read as well as where it is written: a file edited by hand
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never passed the seed.
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Args:
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value: the raw column.
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instance: named in the error, so a bad row can be found.
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Raises:
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DatabasesCsvError: the column is empty, literally ``nan``, or holds
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anything but letters, numbers, ``_`` and ``-``.
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"""
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text = (value or "").strip()
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if not text:
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raise DatabasesCsvError(
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f"Invalid databases.csv entry for instance '{instance}': column "
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f"'database' must be '{CLUSTER_ROW}' or a concrete database name "
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"(not empty)."
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)
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if text == CLUSTER_ROW:
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return CLUSTER_ROW
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if text.lower() == "nan":
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raise DatabasesCsvError(
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f"Invalid databases.csv entry for instance '{instance}': "
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"database must not be 'nan'."
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)
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if not _NAME_RE.match(text):
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raise DatabasesCsvError(
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f"Invalid databases.csv entry for instance '{instance}': invalid "
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f"database name '{text}'. Allowed: letters, numbers, '_' and '-'."
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)
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return text
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def read_rows(csv_path: str) -> list[Row]:
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"""Every row of the file in file order, header skipped, blank rows dropped.
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Raises:
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DatabasesCsvError: a row holds fewer columns than :data:`COLUMNS`.
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"""
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rows: list[Row] = []
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with open(csv_path, newline="", encoding="utf-8") as handle:
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reader = csv.reader(handle, delimiter=DELIMITER)
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next(reader, None)
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for raw in reader:
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if not any(field.strip() for field in raw):
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continue
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if len(raw) < len(COLUMNS):
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raise DatabasesCsvError(
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f"{csv_path} has a row with {len(raw)} column(s), "
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f"expected {len(COLUMNS)}"
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)
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rows.append(Row(*raw[: len(COLUMNS)]))
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return rows
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