99 lines
3.6 KiB
Python
99 lines
3.6 KiB
Python
 
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"""Per-plugin Alembic migration runner + install/uninstall lifecycle (SPEC §11.1).
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Each plugin ships its own revision directory (``Plugin.migrations``) and runs
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against a dedicated version table, so its schema history is independent of core
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and of other plugins. ``install`` upgrades to head; ``uninstall --drop-data``
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runs the plugin's downgrade chain and removes the version table, leaving zero
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residue (the §12 M3 acceptance round-trip). Builtin (core) plugins refuse removal.
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"""
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from __future__ import annotations
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import asyncio
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import logging
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from pathlib import Path
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from alembic import command
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from alembic.config import Config
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from sqlalchemy import text
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from sqlalchemy.ext.asyncio import create_async_engine
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from sqlalchemy.pool import NullPool
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from app.config import get_settings
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from app.plugins import loader
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from app.plugins.types import Plugin
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logger = logging.getLogger(__name__)
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_SHARED_ENV = str(Path(__file__).parent / "alembic")
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class PluginMigrationError(Exception):
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"""Raised when a plugin's migrations can't be run."""
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def _version_table(plugin: Plugin) -> str:
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# plugin.name is validated [a-z][a-z0-9_]* at construction, so this is safe to
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# interpolate into DDL.
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return f"alembic_version_plg_{plugin.name}"
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def _config(plugin: Plugin) -> Config:
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if not plugin.migrations:
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raise PluginMigrationError(f"plugin {plugin.name!r} declares no migrations")
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cfg = Config()
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cfg.set_main_option("script_location", _SHARED_ENV)
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cfg.set_main_option("version_locations", plugin.migrations)
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cfg.set_main_option("path_separator", "os") # split version_locations on os.pathsep only
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cfg.set_main_option("version_table", _version_table(plugin))
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return cfg
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def upgrade(plugin: Plugin, revision: str = "head") -> None:
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"""Run the plugin's migrations up to ``revision`` (default: head)."""
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command.upgrade(_config(plugin), revision)
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def downgrade(plugin: Plugin, revision: str = "base") -> None:
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"""Run the plugin's downgrades to ``revision`` (default: base = drop all)."""
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command.downgrade(_config(plugin), revision)
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async def _drop_version_table(plugin: Plugin) -> None:
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# Fresh engine (not the shared global one) so this is safe to call from any loop.
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engine = create_async_engine(get_settings().database_url, poolclass=NullPool)
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try:
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async with engine.begin() as conn:
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await conn.execute(text(f"DROP TABLE IF EXISTS {_version_table(plugin)}"))
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finally:
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await engine.dispose()
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def install(name: str) -> None:
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"""Apply a plugin's migrations (create its ``plg_*`` tables). No-op if none."""
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plugin = loader.get_plugin(name)
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if plugin is None:
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raise PluginMigrationError(f"unknown plugin {name!r}")
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if plugin.migrations is None:
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logger.info("plugin %s has no migrations; nothing to install", name)
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return
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logger.info("installing plugin %s: upgrade -> head", name)
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upgrade(plugin, "head")
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def uninstall(name: str, *, drop_data: bool = False) -> None:
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"""Uninstall a plugin. Refuses builtin plugins.
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Without ``drop_data`` the schema/data are kept (a reversible disable). With
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``drop_data`` the downgrade chain runs and the version table is removed, so
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nothing remains in the database (SPEC §12 M3 acceptance)."""
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plugin = loader.assert_removable(name) # raises PluginRemovalError for builtin/unknown
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if not drop_data:
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logger.info("uninstalling plugin %s (data kept)", name)
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return
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if plugin.migrations is None:
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return
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logger.info("uninstalling plugin %s --drop-data: downgrade -> base", name)
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downgrade(plugin, "base")
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asyncio.run(_drop_version_table(plugin))
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