app.py

import os
import streamlit as st
import streamlit.components.v1 as components

st.set_page_config(layout="wide")

# List of backend URLs
backends = ["backend1", "backend2", "backend3", "backend4"]

# Randomly select a backend URL
backend = random.choice(backends)
backend_url = os.getenv(backend, "https://www.bytedance.com/en/")  # 如果环境变量不存在，则使用默认 URL

iframe_html = f'<iframe src="{backend_url}" width="100%" height="800"></iframe>'

components.html(iframe_html, height=800)