Hello, I am implementing Phoenix as a test in ECS and I am having some problems with the UI. At the moment I am doing a simple test and I have the following problems:
The task is running ok and healthy in ECS
This si my docker file:
FROM arizephoenix/phoenix:latest
ENV PHOENIX_HOST_ROOT_PATH="/csg-innv-mcp-phoenix-ecs"
VOLUME ["/phoenix/data"]
EXPOSE 80When I try to get my ui to see the projects or something I get this!
The PHOENIX_HOST_ROOT_PATH environment variable is only effective when Phoenix is deployed behind a reverse proxy that rewrites the path prefix; setting it in the Dockerfile alone does not make Phoenix serve at a subpath automatically. If you access Phoenix at a subpath (e.g., /csg-innv-mcp-phoenix-ecs) without a properly configured reverse proxy, static assets (like JS files) will fail to load, resulting in a blank or broken UI. This is a common issue and is documented in several support threads and issues—see this GitHub issue and Slack discussion.To resolve this, you must deploy Phoenix behind a reverse proxy (such as NGINX, Traefik, or an AWS Application Load Balancer) that rewrites the incoming subpath to / and forwards requests to the Phoenix container, with PHOENIX_HOST_ROOT_PATH set to your subpath. Without this, Phoenix will not recognize or serve assets at the subpath, and the UI will not function correctly. Would you like more detail on how to configure the reverse proxy for this setup?Sources:
- GitHub Issue: Static files fail to load with ingress prefix route
- Slack: PHOENIX_HOST_ROOT_PATH and reverse proxy explanation
💡 Hint: Mention RunLLM in the thread for followups.
I actually can't repro anymore either.
If the PHOENIX_HOST_ROOT_PATH is removed I get errors in the routing of the assets
looks familiar try running ensure npm run build is called prior to running the app I ran a similar problem trying to run phoenix in dev mode where logs were suggesting issues with the assets, npm run build solved it for me
