When calling the Hugging Face Inference API (e.g., for Stable Diffusion image generation) from a Vercel serverless function, I'm consistently receiving 504 Gateway Timeout errors.
Root Cause
After investigation, it appears that the Hugging Face model's inference time sometimes exceeds the execution timeout limit imposed by Vercel's serverless infrastructure. This results in the Vercel edge function terminating before Hugging Face can respond.
Why this happens
Vercel’s serverless functions are optimized for fast, low-latency responses. Long-running API calls (like image generation or large model inference) can easily exceed the timeout threshold (typically 10 seconds on the free plan, and ~60 seconds on Pro).
Steps to Reproduce
- Deploy a Next.js (or similar) app on Vercel
- Add an API route that sends a POST request to Hugging Face’s Stable Diffusion endpoint
- Deploy and hit the endpoint from the frontend
- Observe the 504 response after ~10–60 seconds
Possible Solutions
- Move inference calls to a backend with longer execution time (e.g., AWS Lambda with extended timeout, or a dedicated server).
- Queue the request and poll for the result after the function returns.
- Cache Hugging Face model in a managed runtime or use a lightweight model for faster responses.
When calling the Hugging Face Inference API (e.g., for Stable Diffusion image generation) from a Vercel serverless function, I'm consistently receiving
504 Gateway Timeouterrors.Root Cause
After investigation, it appears that the Hugging Face model's inference time sometimes exceeds the execution timeout limit imposed by Vercel's serverless infrastructure. This results in the Vercel edge function terminating before Hugging Face can respond.
Why this happens
Vercel’s serverless functions are optimized for fast, low-latency responses. Long-running API calls (like image generation or large model inference) can easily exceed the timeout threshold (typically 10 seconds on the free plan, and ~60 seconds on Pro).
Steps to Reproduce
Possible Solutions