145 lines
4.1 KiB
Python
145 lines
4.1 KiB
Python
import hashlib
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import logging
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from dataclasses import dataclass
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from enum import Enum
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from typing import Optional
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from redis import ResponseError
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from redis_developer.connections import get_redis_connection
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from redis_developer.model.model import model_registry
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redis = get_redis_connection()
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log = logging.getLogger(__name__)
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import importlib # noqa: E402
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import pkgutil # noqa: E402
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class MigrationError(Exception):
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pass
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def import_submodules(root_module_name: str):
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"""Import all submodules of a module, recursively."""
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# TODO: Call this without specifying a module name, to import everything?
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root_module = importlib.import_module(root_module_name)
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if not hasattr(root_module, "__path__"):
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raise MigrationError(
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"The root module must be a Python package. "
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f"You specified: {root_module_name}"
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)
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for loader, module_name, is_pkg in pkgutil.walk_packages(
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root_module.__path__, root_module.__name__ + "." # type: ignore
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):
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importlib.import_module(module_name)
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def schema_hash_key(index_name):
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return f"{index_name}:hash"
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def create_index(index_name, schema, current_hash):
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try:
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redis.execute_command(f"ft.info {index_name}")
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except ResponseError:
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log.info("Index already exists, skipping. Index hash: %s", index_name)
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return
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redis.execute_command(f"ft.create {index_name} {schema}")
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redis.set(schema_hash_key(index_name), current_hash)
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class MigrationAction(Enum):
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CREATE = 2
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DROP = 1
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@dataclass
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class IndexMigration:
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model_name: str
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index_name: str
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schema: str
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hash: str
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action: MigrationAction
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previous_hash: Optional[str] = None
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def run(self):
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if self.action is MigrationAction.CREATE:
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self.create()
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elif self.action is MigrationAction.DROP:
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self.drop()
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def create(self):
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return create_index(self.index_name, self.schema, self.hash)
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def drop(self):
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redis.execute_command(f"FT.DROPINDEX {self.index_name}")
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class Migrator:
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def __init__(self, module=None):
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# Try to load any modules found under the given path or module name.
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if module:
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import_submodules(module)
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self.migrations = []
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for name, cls in model_registry.items():
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hash_key = schema_hash_key(cls.Meta.index_name)
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try:
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schema = cls.redisearch_schema()
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except NotImplementedError:
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log.info("Skipping migrations for %s", name)
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continue
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current_hash = hashlib.sha1(schema.encode("utf-8")).hexdigest() # nosec
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try:
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redis.execute_command("ft.info", cls.Meta.index_name)
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except ResponseError:
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self.migrations.append(
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IndexMigration(
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name,
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cls.Meta.index_name,
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schema,
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current_hash,
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MigrationAction.CREATE,
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)
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)
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continue
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stored_hash = redis.get(hash_key)
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schema_out_of_date = current_hash != stored_hash
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if schema_out_of_date:
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# TODO: Switch out schema with an alias to avoid downtime -- separate migration?
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self.migrations.append(
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IndexMigration(
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name,
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cls.Meta.index_name,
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schema,
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current_hash,
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MigrationAction.DROP,
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stored_hash,
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)
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)
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self.migrations.append(
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IndexMigration(
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name,
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cls.Meta.index_name,
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schema,
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current_hash,
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MigrationAction.CREATE,
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stored_hash,
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)
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)
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def run(self):
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# TODO: Migration history
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# TODO: Dry run with output
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for migration in self.migrations:
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migration.run()
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