# Guaranteed Availability

Implementing this is usually not necessary as it adds complexity to your application. The Langfuse Prompt Management is highly available due to multiple [caching layers](/content/docs/prompt-management/features/caching/index.html) and we closely monitor its performance ( [status page](https://status.langfuse.com/)). However, if you require 100% availability, you can use the following options.

The Langfuse API has high uptime and prompts are [cached locally](/content/docs/prompt-management/features/caching/index.html) in the SDKs to prevent network issues from affecting your application.

However, `get_prompt()`/`getPrompt()` will throw an exception if:

- No local (fresh or stale) cached prompt is available -> new application instance fetching prompt for the first time
- _and_ network request fails -> networking or Langfuse API issue (after retries)

To guarantee 100% availability, there are two options:

1. **Pre-fetch prompts** on application startup and exit the application if the prompt is not available.
2. Provide a **fallback** prompt that will be used in these cases.

## Option 1: Pre-fetch prompts

Pre-fetch prompts on application startup and exit the application if the prompt is not available.

### Python (Flask)
```python
from flask import Flask, jsonify
from langfuse import Langfuse

# Initialize the Flask app and Langfuse client
app = Flask(__name__)
langfuse = Langfuse()

def fetch_prompts_on_startup():
    try:
        # Fetch and cache the production version of the prompt
        langfuse.get_prompt("movie-critic")
    except Exception as e:
        print(f"Failed to fetch prompt on startup: {e}")
        sys.exit(1)  # Exit the application if the prompt is not available

# Call the function during application startup
fetch_prompts_on_startup()

@app.route('/get-movie-prompt/<movie>', methods=['GET'])
def get_movie_prompt(movie):
    prompt = langfuse.get_prompt("movie-critic")
    compiled_prompt = prompt.compile(criticlevel="expert", movie=movie)
    return jsonify({"prompt": compiled_prompt})

if __name__ == '__main__':
    app.run(debug=True)
```

### JS/TS (Express)
```javascript
import express from "express";
import { LangfuseClient } from "@langfuse/client";

// Initialize the Express app and Langfuse client
const app = express();
const langfuse = new LangfuseClient();

async function fetchPromptsOnStartup() {
  try {
    // Fetch and cache the production version of the prompt
    await langfuse.prompt.get("movie-critic");
  } catch (error) {
    console.error("Failed to fetch prompt on startup:", error);
    process.exit(1); // Exit the application if the prompt is not available
  }
}

// Call the function during application startup
fetchPromptsOnStartup();

app.get("/get-movie-prompt/:movie", async (req, res) => {
  const movie = req.params.movie;
  const prompt = await langfuse.prompt.get("movie-critic");
  const compiledPrompt = prompt.compile({ criticlevel: "expert", movie });
  res.json({ prompt: compiledPrompt });
});

app.listen(3000, () => {
  console.log("Server is running on port 3000");
});
```

## Option 2: Fallback

Provide a fallback prompt that will be used in these cases:

### Python SDK
```python
from langfuse import Langfuse
langfuse = Langfuse()

# Get `text` prompt with fallback
prompt = langfuse.get_prompt(
  "movie-critic",
  fallback="Do you like {{movie}}?"
)

# Get `chat` prompt with fallback
chat_prompt = langfuse.get_prompt(
  "movie-critic-chat",
  type="chat",
  fallback=[{"role": "system", "content": "You are an expert on {{movie}}"}]
)

# True if the prompt is a fallback
prompt.is_fallback
```

### JS/TS SDK
```javascript
import { LangfuseClient } from "@langfuse/client";

const langfuse = new LangfuseClient();

// Get `text` prompt with fallback
const prompt = await langfuse.prompt.get("movie-critic", {
  fallback: "Do you like {{movie}}?",
});

// Get `chat` prompt with fallback
const chatPrompt = await langfuse.prompt.get("movie-critic-chat", {
  type: "chat",
  fallback: [{ role: "system", content: "You are an expert on {{movie}}" }],
});

// True if the prompt is a fallback
prompt.isFallback;
```