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Environment Variables

Setting boolean values

To set a boolean True, use one of the following string values: "true", "1" or "yes". Any other value will be interpreted as False.

FLET_APP_CONSOLE​

The path to the application's console log file (console.log) in the temporary storage directory.

Its value is set in production mode.

FLET_APP_STORAGE_DATA​

A directory for the storage of persistent application data that is preserved between app updates. It is already pre-created and its location depends on the platform the app is running on.

FLET_APP_STORAGE_TEMP​

A directory for the storage of temporary application files, i.e. cache. It is already pre-created and its location depends on the platform the app is running on.

FLET_ASSETS_DIR​

Absolute path to the app's assets directory.

In production apps built with flet build, this environment-variable points to the bundled assets absolute location at runtime. Use it when your code needs a filesystem path to bundled files (for example, JSON configs, databases, or model files).

For local runs, it may be unset depending on how the app is started, so use a fallback:

import os
from pathlib import Path
import flet as ft

default_assets_dir = Path(__file__).parent / "assets"
assets_dir = Path(os.environ.get("FLET_ASSETS_DIR", str(default_assets_dir))).resolve()

def main(page: ft.Page):
	...

ft.run(main, assets_dir="assets")

For control properties like Image.src, continue using paths relative to the ft.run(assets_dir=...), as described in the assets cookbook.

FLET_ANDROID_SIGNING_KEY_ALIAS​

Android signing key alias used by flet build for Android app signing.

It is used only when a keystore is configured.

FLET_ANDROID_SIGNING_KEY_PASSWORD​

Android signing key password used by flet build for Android app signing.

If FLET_ANDROID_SIGNING_KEY_STORE_PASSWORD is set but this variable is not, the keystore password is reused as the key password.

FLET_ANDROID_SIGNING_KEY_STORE​

Path to the Android upload keystore (.jks) used by flet build for Android app signing.

FLET_ANDROID_SIGNING_KEY_STORE_PASSWORD​

Android signing keystore password used by flet build for Android app signing.

If FLET_ANDROID_SIGNING_KEY_PASSWORD is set but this variable is not, the key password is reused as the keystore password.

FLET_CLI_NO_RICH_OUTPUT​

Whether to disable rich output in the console.

Defaults to "false".

FLET_PLATFORM​

The platform on which the application is running. Its value is one of the following: "android", "ios", "linux", "macos", "windows" or "fuchsia".

FLET_CLI_SKIP_FLUTTER_DOCTOR​

Whether to skip running flutter doctor when a build fails.

Defaults to False.

FLET_HIDE_WINDOW_ON_START​

Set to true to start app with the main window hidden.

Defaults to False.

FLET_FORCE_WEB_SERVER​

Set to true to force running app as a web app. Automatically set on headless Linux hosts.

FLET_OAUTH_CALLBACK_HANDLER_ENDPOINT​

Custom path for OAuth handler.

Defaults to "/oauth_callback".

FLET_OAUTH_STATE_TIMEOUT​

Maximum allowed time (in seconds) to complete OAuth web flow.

Defaults to 600.

FLET_MAX_UPLOAD_SIZE​

Maximum allowed size (in bytes) of uploaded files.

Default is unlimited.

FLET_SECRET_KEY​

A secret key to sign temporary upload URLs.

FLET_SERVER_IP​

IP address to listen web app on, e.g. "127.0.0.1".

Defaults to 0.0.0.0 - bound to all server IPs.

FLET_SERVER_PORT​

TCP port to run app on.

8000 if the program is running on a Linux server or FLET_FORCE_WEB_SERVER is set; otherwise random port.

FLET_SERVER_UDS_PATH​

The Unix Domain Socket (UDS) path for the Flet server. It enables inter-process communication on Unix-based systems, with its value being a socket file path in the format flet_<pid>.sock.

FLET_SESSION_TIMEOUT​

Session lifetime in seconds.

Defaults to 3600.

FLET_UPLOAD_DIR​

Absolute path to app "upload" directory.

FLET_UPLOAD_HANDLER_ENDPOINT​

Custom path for upload handler.

Defaults to "/upload".

FLET_WEB_APP_PATH​

A URL path after domain name to host web app under, e.g. "/apps/myapp".

Defaults to "/" - host app in the root.

FLET_WEB_NO_CDN​

Set to true to avoid loading CanvasKit, Pyodide, and fonts from CDNs.

FLET_WEBSOCKET_HANDLER_ENDPOINT​

Custom path for WebSocket handler.

Defaults to "/ws".

FLET_WEB_RENDERER​

Web rendering mode: "canvaskit" (default), "skwasm" or "auto".

FLET_WEB_USE_COLOR_EMOJI​

Set to True, true or 1 to load web font with colorful emojis.

FLET_WEB_ROUTE_URL_STRATEGY​

The URL strategy of the web application. Its value can be either "path" (default) or "hash".