Added better CLI docs in README and bumps langchain-serve (#590)

src/backend/langflow/__init__.py

@@ -1,6 +1,6 @@
 from importlib import metadata
-from langflow.cache import cache_manager
-from langflow.processing.process import load_flow_from_json
+from langflow.cache import cache_manager  # noqa: E402
+from langflow.processing.process import load_flow_from_json  # noqa: E402
 
 try:
     __version__ = metadata.version(__package__)
@@ -9,4 +9,5 @@ except metadata.PackageNotFoundError:
     __version__ = ""
 del metadata  # optional, avoids polluting the results of dir(__package__)
 
+
 __all__ = ["load_flow_from_json", "cache_manager"]

src/backend/langflow/__main__.py

@@ -1,3 +1,4 @@
+import os
 import sys
 import time
 import httpx
@@ -33,6 +34,10 @@ def update_settings(
     remove_api_keys: bool = False,
 ):
     """Update the settings from a config file."""
+
+    # Check for database_url in the environment variables
+    database_url = database_url or os.getenv("langflow_database_url")
+
     if config:
         settings.update_from_yaml(config, dev=dev)
     if database_url:
@@ -91,19 +96,27 @@ def serve_on_jcloud():
 
 @app.command()
 def serve(
-    host: str = typer.Option("127.0.0.1", help="Host to bind the server to."),
-    workers: int = typer.Option(1, help="Number of worker processes."),
+    host: str = typer.Option(
+        "127.0.0.1", help="Host to bind the server to.", envvar="LANGFLOW_HOST"
+    ),
+    workers: int = typer.Option(
+        1, help="Number of worker processes.", envvar="LANGFLOW_WORKERS"
+    ),
     timeout: int = typer.Option(60, help="Worker timeout in seconds."),
-    port: int = typer.Option(7860, help="Port to listen on."),
+    port: int = typer.Option(7860, help="Port to listen on.", envvar="LANGFLOW_PORT"),
     config: str = typer.Option("config.yaml", help="Path to the configuration file."),
     # .env file param
     env_file: Path = typer.Option(
         ".env", help="Path to the .env file containing environment variables."
     ),
-    log_level: str = typer.Option("critical", help="Logging level."),
-    log_file: Path = typer.Option("logs/langflow.log", help="Path to the log file."),
-    cache: str = typer.Argument(
-        envvar="LANGCHAIN_CACHE",
+    log_level: str = typer.Option(
+        "critical", help="Logging level.", envvar="LANGFLOW_LOG_LEVEL"
+    ),
+    log_file: Path = typer.Option(
+        "logs/langflow.log", help="Path to the log file.", envvar="LANGFLOW_LOG_FILE"
+    ),
+    cache: str = typer.Option(
+        envvar="LANGFLOW_LANGCHAIN_CACHE",
         help="Type of cache to use. (InMemoryCache, SQLiteCache)",
         default="SQLiteCache",
     ),
@@ -112,27 +125,34 @@ def serve(
     database_url: str = typer.Option(
         None,
         help="Database URL to connect to. If not provided, a local SQLite database will be used.",
+        envvar="LANGFLOW_DATABASE_URL",
     ),
     path: str = typer.Option(
         None,
         help="Path to the frontend directory containing build files. This is for development purposes only.",
+        envvar="LANGFLOW_FRONTEND_PATH",
     ),
     open_browser: bool = typer.Option(
-        True, help="Open the browser after starting the server."
+        True,
+        help="Open the browser after starting the server.",
+        envvar="LANGFLOW_OPEN_BROWSER",
     ),
     remove_api_keys: bool = typer.Option(
-        False, help="Remove API keys from the projects saved in the database."
+        False,
+        help="Remove API keys from the projects saved in the database.",
+        envvar="LANGFLOW_REMOVE_API_KEYS",
     ),
 ):
     """
     Run the Langflow server.
     """
+    # override env variables with .env file
+    if env_file:
+        load_dotenv(env_file, override=True)
 
     if jcloud:
         return serve_on_jcloud()
 
-    load_dotenv(env_file)
-
     configure(log_level=log_level, log_file=log_file)
     update_settings(
         config,

src/backend/langflow/database/base.py

@@ -2,17 +2,34 @@ from langflow.settings import settings
 from sqlmodel import SQLModel, Session, create_engine
 from langflow.utils.logger import logger
 
-if settings.database_url.startswith("sqlite"):
+if settings.database_url and settings.database_url.startswith("sqlite"):
     connect_args = {"check_same_thread": False}
 else:
     connect_args = {}
+if not settings.database_url:
+    raise RuntimeError("No database_url provided")
 engine = create_engine(settings.database_url, connect_args=connect_args)
 
 
 def create_db_and_tables():
     logger.debug("Creating database and tables")
-    SQLModel.metadata.create_all(engine)
-    logger.debug("Database and tables created")
+    try:
+        SQLModel.metadata.create_all(engine)
+    except Exception as exc:
+        logger.error(f"Error creating database and tables: {exc}")
+        raise RuntimeError("Error creating database and tables") from exc
+    # Now check if the table Flow exists, if not, something went wrong
+    # and we need to create the tables again.
+    from sqlalchemy import inspect
+
+    inspector = inspect(engine)
+    if "flow" not in inspector.get_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.")
+    else:
+        logger.debug("Database and tables created successfully")
 
 
 def get_session():

src/backend/langflow/interface/utils.py

@@ -66,17 +66,24 @@ def extract_input_variables_from_prompt(prompt: str) -> list[str]:
 def setup_llm_caching():
     """Setup LLM caching."""
 
+    from langflow.settings import settings
+
     try:
-        import langchain
-        from langflow.settings import settings
-        from langflow.interface.importing.utils import import_class
-
-        cache_class = import_class(f"langchain.cache.{settings.cache}")
-
-        logger.debug(f"Setting up LLM caching with {cache_class.__name__}")
-        langchain.llm_cache = cache_class()
-        logger.info(f"LLM caching setup with {cache_class.__name__}")
+        set_langchain_cache(settings)
     except ImportError:
         logger.warning(f"Could not import {settings.cache}. ")
     except Exception as exc:
         logger.warning(f"Could not setup LLM caching. Error: {exc}")
+
+
+# TODO Rename this here and in `setup_llm_caching`
+def set_langchain_cache(settings):
+    import langchain
+    from langflow.interface.importing.utils import import_class
+
+    cache_type = os.getenv("LANGFLOW_LANGCHAIN_CACHE")
+    cache_class = import_class(f"langchain.cache.{cache_type or settings.cache}")
+
+    logger.debug(f"Setting up LLM caching with {cache_class.__name__}")
+    langchain.llm_cache = cache_class()
+    logger.info(f"LLM caching setup with {cache_class.__name__}")

src/backend/langflow/lcserve.py

@@ -1,16 +1,7 @@
 # This file is used by lc-serve to load the mounted app and serve it.
 
-from pathlib import Path
+from langflow.main import setup_app
+from langflow.utils.logger import configure
 
-from fastapi.staticfiles import StaticFiles
-
-from langflow.main import create_app
-
-app = create_app()
-path = Path(__file__).parent
-static_files_dir = path / "frontend"
-app.mount(
-    "/",
-    StaticFiles(directory=static_files_dir, html=True),
-    name="static",
-)
+configure(log_level="DEBUG")
+app = setup_app()

src/backend/langflow/main.py

@@ -61,7 +61,7 @@ def setup_static_files(app: FastAPI, static_files_dir: Path):
 
 # app = create_app()
 # setup_static_files(app, static_files_dir)
-def setup_app(static_files_dir: Optional[Path]) -> FastAPI:
+def setup_app(static_files_dir: Optional[Path] = None) -> FastAPI:
     """Setup the FastAPI app."""
     # get the directory of the current file
     if not static_files_dir:

src/backend/langflow/settings.py

@@ -1,4 +1,5 @@
 import os
+from typing import Optional
 
 import yaml
 from pydantic import BaseSettings, root_validator
@@ -21,16 +22,18 @@ class Settings(BaseSettings):
     textsplitters: dict = {}
     utilities: dict = {}
     dev: bool = False
-    database_url: str
+    database_url: Optional[str] = None
     cache: str = "InMemoryCache"
     remove_api_keys: bool = False
 
     @root_validator(pre=True)
     def set_database_url(cls, values):
         if "database_url" not in values:
-            logger.debug("No database_url provided, trying DATABASE_URL env variable")
-            if database_url := os.getenv("DATABASE_URL"):
-                values["database_url"] = database_url
+            logger.debug(
+                "No database_url provided, trying LANGFLOW_DATABASE_URL env variable"
+            )
+            if langflow_database_url := os.getenv("LANGFLOW_DATABASE_URL"):
+                values["database_url"] = langflow_database_url
             else:
                 logger.debug("No DATABASE_URL env variable, using sqlite database")
                 values["database_url"] = "sqlite:///./langflow.db"
@@ -39,7 +42,6 @@ class Settings(BaseSettings):
     class Config:
         validate_assignment = True
         extra = "ignore"
-        env_prefix = "LANGFLOW_"
 
     @root_validator(allow_reuse=True)
     def validate_lists(cls, values):