Files
shopdb-flask/shopdb/plugins/migrations.py

254 lines
8.8 KiB
Python

"""Plugin migration management using Alembic."""
from pathlib import Path
from typing import Optional
import logging
import subprocess
import sys
logger = logging.getLogger(__name__)
class PluginMigrationManager:
"""
Manages database migrations for plugins.
Each plugin has its own migrations directory.
"""
def __init__(self, plugins_dir: Path, database_url: str):
self.plugins_dir = plugins_dir
self.database_url = database_url
# Set by PluginManager.init_app; a PluginVerifier or None (no policy).
self.verifier = None
def _verify_ok(self, plugin_name: str) -> bool:
"""Strip bytecode + verify the tree before ANY alembic import.
Alembic imports env.py and every versions/*.py module body (running
their top-level code) with full DB rights, so every method that reaches
alembic for a plugin must pass through here first (finding #3).
"""
if self.verifier is None or not self.verifier.require_signed:
return True
from .packaging import strip_bytecode
strip_bytecode(self.plugins_dir / plugin_name)
ok, reason = self.verifier.check(plugin_name)
if not ok:
logger.error(
"Refusing plugin migration code for %s: %s", plugin_name, reason)
return ok
def get_migrations_dir(self, plugin_name: str) -> Optional[Path]:
"""Get migrations directory for a plugin."""
migrations_dir = self.plugins_dir / plugin_name / 'migrations'
if migrations_dir.exists():
return migrations_dir
return None
def run_plugin_migrations(
self,
plugin_name: str,
revision: str = 'head'
) -> bool:
"""
Run migrations for a plugin.
Uses flask db upgrade with the plugin's migrations directory.
"""
# verify-at-migrate: never run a plugin's migration code (full DB rights)
# from an unverified tree when the site enforces signing.
if not self._verify_ok(plugin_name):
return False
migrations_dir = self.get_migrations_dir(plugin_name)
if not migrations_dir:
logger.info(f"No migrations directory for plugin {plugin_name}")
return True # No migrations to run
try:
# Use alembic directly with plugin's migrations
from alembic.config import Config
from alembic import command
from .packaging import no_bytecode
config = Config()
config.set_main_option('script_location', str(migrations_dir))
config.set_main_option('sqlalchemy.url', self.database_url)
# Use plugin-specific version table
config.set_main_option(
'version_table',
f'alembic_version_{plugin_name}'
)
with no_bytecode():
command.upgrade(config, revision)
logger.info(f"Migrations completed for {plugin_name}")
return True
except ImportError:
# Fallback to subprocess if alembic not available in context
logger.warning("Using subprocess for migrations")
return self._run_migrations_subprocess(plugin_name, revision)
except Exception as e:
logger.error(f"Migration failed for {plugin_name}: {e}")
return False
def _run_migrations_subprocess(
self,
plugin_name: str,
revision: str = 'head'
) -> bool:
"""Run migrations via subprocess as fallback."""
if not self._verify_ok(plugin_name):
return False
migrations_dir = self.get_migrations_dir(plugin_name)
if not migrations_dir:
return True
try:
result = subprocess.run(
[
sys.executable, '-B', '-m', 'alembic',
'-c', str(migrations_dir / 'alembic.ini'),
'upgrade', revision
],
capture_output=True,
text=True,
env={
**dict(__import__('os').environ),
'DATABASE_URL': self.database_url,
'PYTHONDONTWRITEBYTECODE': '1',
}
)
if result.returncode != 0:
logger.error(f"Migration error: {result.stderr}")
return False
return True
except Exception as e:
logger.error(f"Migration subprocess failed: {e}")
return False
def downgrade_plugin(
self,
plugin_name: str,
revision: str = 'base'
) -> bool:
"""
Downgrade/rollback plugin migrations.
"""
# Downgrade runs the same env.py + version module code as upgrade, so it
# gets the same fail-closed verification (finding #3: this path had none).
if not self._verify_ok(plugin_name):
return False
migrations_dir = self.get_migrations_dir(plugin_name)
if not migrations_dir:
return True
try:
from alembic.config import Config
from alembic import command
from .packaging import no_bytecode
config = Config()
config.set_main_option('script_location', str(migrations_dir))
config.set_main_option('sqlalchemy.url', self.database_url)
config.set_main_option(
'version_table',
f'alembic_version_{plugin_name}'
)
with no_bytecode():
command.downgrade(config, revision)
logger.info(f"Downgrade completed for {plugin_name}")
return True
except Exception as e:
logger.error(f"Downgrade failed for {plugin_name}: {e}")
return False
def get_current_revision(self, plugin_name: str) -> Optional[str]:
"""Get current migration revision for a plugin.
ScriptDirectory imports every versions/*.py to build the revision map,
so this reads (executes) plugin code and must verify first (finding #3).
"""
if not self._verify_ok(plugin_name):
return None
migrations_dir = self.get_migrations_dir(plugin_name)
if not migrations_dir:
return None
try:
from alembic.config import Config
from alembic.script import ScriptDirectory
from .packaging import no_bytecode
config = Config()
config.set_main_option('script_location', str(migrations_dir))
with no_bytecode():
script = ScriptDirectory.from_config(config)
return script.get_current_head()
except Exception:
return None
def has_pending_migrations(self, plugin_name: str) -> bool:
"""Check if plugin has any migration scripts on disk.
File-level check only (no DB): True when the plugin ships a
migrations/versions dir with at least one script. Used by
upgrade-all to decide whether the plugin participates in the
per-plugin Alembic flow at all.
"""
migrations_dir = self.get_migrations_dir(plugin_name)
if not migrations_dir:
return False
versions_dir = migrations_dir / 'versions'
if not versions_dir.exists():
return False
# Any migration files on disk?
migration_files = list(versions_dir.glob('*.py'))
return len(migration_files) > 0
def get_applied_revision(self, plugin_name: str) -> Optional[str]:
"""Return the revision stamped in alembic_version_<plugin> in the DB,
or None if the plugin chain has never been stamped (or on any error)."""
migrations_dir = self.get_migrations_dir(plugin_name)
if not migrations_dir or not self.database_url:
return None
try:
from sqlalchemy import create_engine
from alembic.runtime.migration import MigrationContext
engine = create_engine(self.database_url)
with engine.connect() as connection:
context = MigrationContext.configure(
connection,
opts={'version_table': f'alembic_version_{plugin_name}'},
)
return context.get_current_revision()
except Exception:
return None
def has_unapplied_migrations(self, plugin_name: str) -> bool:
"""True when the plugin's on-disk chain head is ahead of what the DB
has stamped. Compares the script head against alembic_version_<plugin>.
Best-effort: returns False when it cannot tell (no chain / no DB)."""
head = self.get_current_revision(plugin_name) # script head on disk
if not head:
return False
return self.get_applied_revision(plugin_name) != head