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service.py
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service.py
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import time
from datetime import datetime
from pathlib import Path
from typing import TYPE_CHECKING
import sqlalchemy as sa
from alembic import command, util
from alembic.config import Config
from langflow.services.base import Service
from langflow.services.database import models # noqa
from langflow.services.database.models.user.crud import get_user_by_username
from langflow.services.database.utils import Result, TableResults
from langflow.services.deps import get_settings_service
from langflow.services.utils import teardown_superuser
from loguru import logger
from sqlalchemy import event, inspect
from sqlalchemy.engine import Engine
from sqlalchemy.exc import OperationalError
from sqlmodel import Session, SQLModel, create_engine, select, text
if TYPE_CHECKING:
from langflow.services.settings.service import SettingsService
from sqlalchemy.engine import Engine
class DatabaseService(Service):
name = "database_service"
def __init__(self, settings_service: "SettingsService"):
self.settings_service = settings_service
if settings_service.settings.database_url is None:
raise ValueError("No database URL provided")
self.database_url: str = settings_service.settings.database_url
# This file is in langflow.services.database.manager.py
# the ini is in langflow
langflow_dir = Path(__file__).parent.parent.parent
self.script_location = langflow_dir / "alembic"
self.alembic_cfg_path = langflow_dir / "alembic.ini"
self.engine = self._create_engine()
def _create_engine(self) -> "Engine":
"""Create the engine for the database."""
settings_service = get_settings_service()
if settings_service.settings.database_url and settings_service.settings.database_url.startswith("sqlite"):
connect_args = {"check_same_thread": False}
else:
connect_args = {}
try:
return create_engine(
self.database_url,
connect_args=connect_args,
pool_size=self.settings_service.settings.pool_size,
max_overflow=self.settings_service.settings.max_overflow,
)
except sa.exc.NoSuchModuleError as exc:
# sqlalchemy.exc.NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:postgres
if "postgres" in str(exc) and not self.database_url.startswith("postgresql"):
# https://stackoverflow.com/questions/62688256/sqlalchemy-exc-nosuchmoduleerror-cant-load-plugin-sqlalchemy-dialectspostgre
self.database_url = self.database_url.replace("postgres://", "postgresql://")
logger.warning(
"Fixed postgres dialect in database URL. Replacing postgres:// with postgresql://. To avoid this warning, update the database URL."
)
return self._create_engine()
raise RuntimeError("Error creating database engine") from exc
@event.listens_for(Engine, "connect")
def on_connection(dbapi_connection, connection_record):
from sqlite3 import Connection as sqliteConnection
if isinstance(dbapi_connection, sqliteConnection):
logger.info("sqlite connect listener, setting pragmas")
cursor = dbapi_connection.cursor()
try:
cursor.execute("PRAGMA synchronous = NORMAL")
cursor.execute("PRAGMA journal_mode = WAL")
cursor.close()
except OperationalError as oe:
logger.warning("Failed to set PRAGMA: ", {oe})
def __enter__(self):
self._session = Session(self.engine)
return self._session
def __exit__(self, exc_type, exc_value, traceback):
if exc_type is not None: # If an exception has been raised
logger.error(f"Session rollback because of exception: {exc_type.__name__} {exc_value}")
self._session.rollback()
else:
self._session.commit()
self._session.close()
def get_session(self):
with Session(self.engine) as session:
yield session
def migrate_flows_if_auto_login(self):
# if auto_login is enabled, we need to migrate the flows
# to the default superuser if they don't have a user id
# associated with them
settings_service = get_settings_service()
if settings_service.auth_settings.AUTO_LOGIN:
with Session(self.engine) as session:
flows = session.exec(select(models.Flow).where(models.Flow.user_id is None)).all()
if flows:
logger.debug("Migrating flows to default superuser")
username = settings_service.auth_settings.SUPERUSER
user = get_user_by_username(session, username)
if not user:
logger.error("Default superuser not found")
raise RuntimeError("Default superuser not found")
for flow in flows:
flow.user_id = user.id
session.commit()
logger.debug("Flows migrated successfully")
def check_schema_health(self) -> bool:
inspector = inspect(self.engine)
model_mapping = {
"flow": models.Flow,
"user": models.User,
"apikey": models.ApiKey,
# Add other SQLModel classes here
}
# To account for tables that existed in older versions
legacy_tables = ["flowstyle"]
for table, model in model_mapping.items():
expected_columns = list(model.model_fields.keys())
try:
available_columns = [col["name"] for col in inspector.get_columns(table)]
except sa.exc.NoSuchTableError:
logger.debug(f"Missing table: {table}")
return False
for column in expected_columns:
if column not in available_columns:
logger.debug(f"Missing column: {column} in table {table}")
return False
for table in legacy_tables:
if table in inspector.get_table_names():
logger.warning(f"Legacy table exists: {table}")
return True
def init_alembic(self, alembic_cfg):
logger.info("Initializing alembic")
command.ensure_version(alembic_cfg)
# alembic_cfg.attributes["connection"].commit()
command.upgrade(alembic_cfg, "head")
logger.info("Alembic initialized")
def run_migrations(self, fix=False):
# First we need to check if alembic has been initialized
# If not, we need to initialize it
# if not self.script_location.exists(): # this is not the correct way to check if alembic has been initialized
# We need to check if the alembic_version table exists
# if not, we need to initialize alembic
# stdout should be something like sys.stdout
# which is a buffer
# I don't want to output anything
# subprocess.DEVNULL is an int
buffer = open(self.script_location / "alembic.log", "w")
alembic_cfg = Config(stdout=buffer)
# alembic_cfg.attributes["connection"] = session
alembic_cfg.set_main_option("script_location", str(self.script_location))
alembic_cfg.set_main_option("sqlalchemy.url", self.database_url.replace("%", "%%"))
should_initialize_alembic = False
with Session(self.engine) as session:
# If the table does not exist it throws an error
# so we need to catch it
try:
session.exec(text("SELECT * FROM alembic_version"))
except Exception:
logger.info("Alembic not initialized")
should_initialize_alembic = True
else:
logger.info("Alembic already initialized")
if should_initialize_alembic:
try:
self.init_alembic(alembic_cfg)
except Exception as exc:
logger.error(f"Error initializing alembic: {exc}")
raise RuntimeError("Error initializing alembic") from exc
logger.info(f"Running DB migrations in {self.script_location}")
try:
buffer.write(f"{datetime.now().isoformat()}: Checking migrations\n")
command.check(alembic_cfg)
except Exception as exc:
if isinstance(exc, (util.exc.CommandError, util.exc.AutogenerateDiffsDetected)):
command.upgrade(alembic_cfg, "head")
time.sleep(3)
try:
buffer.write(f"{datetime.now().isoformat()}: Checking migrations\n")
command.check(alembic_cfg)
except util.exc.AutogenerateDiffsDetected as exc:
logger.error(f"AutogenerateDiffsDetected: {exc}")
if not fix:
raise RuntimeError(f"There's a mismatch between the models and the database.\n{exc}")
if fix:
self.try_downgrade_upgrade_until_success(alembic_cfg)
def try_downgrade_upgrade_until_success(self, alembic_cfg, retries=5):
# Try -1 then head, if it fails, try -2 then head, etc.
# until we reach the number of retries
for i in range(1, retries + 1):
try:
command.check(alembic_cfg)
break
except util.exc.AutogenerateDiffsDetected as exc:
# downgrade to base and upgrade again
logger.warning(f"AutogenerateDiffsDetected: {exc}")
command.downgrade(alembic_cfg, f"-{i}")
# wait for the database to be ready
time.sleep(3)
command.upgrade(alembic_cfg, "head")
def run_migrations_test(self):
# This method is used for testing purposes only
# We will check that all models are in the database
# and that the database is up to date with all columns
# get all models that are subclasses of SQLModel
sql_models = [
model for model in models.__dict__.values() if isinstance(model, type) and issubclass(model, SQLModel)
]
return [TableResults(sql_model.__tablename__, self.check_table(sql_model)) for sql_model in sql_models]
def check_table(self, model):
results = []
inspector = inspect(self.engine)
table_name = model.__tablename__
expected_columns = list(model.__fields__.keys())
available_columns = []
try:
available_columns = [col["name"] for col in inspector.get_columns(table_name)]
results.append(Result(name=table_name, type="table", success=True))
except sa.exc.NoSuchTableError:
logger.error(f"Missing table: {table_name}")
results.append(Result(name=table_name, type="table", success=False))
for column in expected_columns:
if column not in available_columns:
logger.error(f"Missing column: {column} in table {table_name}")
results.append(Result(name=column, type="column", success=False))
else:
results.append(Result(name=column, type="column", success=True))
return results
def create_db_and_tables(self):
from sqlalchemy import inspect
inspector = inspect(self.engine)
table_names = inspector.get_table_names()
current_tables = ["flow", "user", "apikey"]
if table_names and all(table in table_names for table in current_tables):
logger.debug("Database and tables already exist")
return
logger.debug("Creating database and tables")
for table in SQLModel.metadata.sorted_tables:
try:
table.create(self.engine, checkfirst=True)
except OperationalError as oe:
logger.warning(f"Table {table} already exists, skipping. Exception: {oe}")
except Exception as exc:
logger.error(f"Error creating table {table}: {exc}")
raise RuntimeError(f"Error creating table {table}") from exc
# Now check if the required tables exist, if not, something went wrong.
inspector = inspect(self.engine)
table_names = inspector.get_table_names()
for table in current_tables:
if table not in table_names:
logger.error("Something went wrong creating the database and tables.")
logger.error("Please check your database settings.")
raise RuntimeError("Something went wrong creating the database and tables.")
logger.debug("Database and tables created successfully")
def teardown(self):
logger.debug("Tearing down database")
try:
settings_service = get_settings_service()
# remove the default superuser if auto_login is enabled
# using the SUPERUSER to get the user
with Session(self.engine) as session:
teardown_superuser(settings_service, session)
except Exception as exc:
logger.error(f"Error tearing down database: {exc}")
self.engine.dispose()
self.engine.dispose()