/gradio_api/heartbeat/<<sess_id>> fails in browser (http code 500)

[ErnstDinkelmann]

Describe the bug

Hi there

Asked in discord, but no response thus far. Not sure it's a bug or our configs.

Issue:
All assets (e.g. css, js, docs) are successfully received in brower (inspect > network), except the heartbeat (which is pending and then returns 500 after some time).
Only happens when a gr.State variable is present.
So the minimal repro only has a gr.State and still the problem happens.

Basic setup:
NGINX reverse proxy. Tried to implement according to deployment guide.
proxy_cookie_flags ~ secure httponly samesite=lax; Have tested without this, makes no difference.
proxy_set_header X-Forwarded-Proto $scheme; Have tested without this, makes no difference.
proxy_set_header X-Forwarded-Host $host; When including this, nothing works. Even using $http_host, nothing works. So not using this header at all. "Connection Errored out" on UI.

Have you searched existing issues? 🔎

• I have searched and found no existing issues

Reproduction

import gradio as gr
from fastapi import FastAPI
import uvicorn

app = FastAPI(debug=True)

with gr.Blocks(analytics_enabled=False) as gr_block_app: 
    a_state = gr.State(None)

gr_block_app.queue()

app = gr.mount_gradio_app(
    app, 
    blocks=gr_block_app, 
    path='/app',
)

uvicorn.run(app, port=8080, host='0.0.0.0')

NGINX
...
http {
        ...
        sendfile on;
        tcp_nopush on;
        keepalive_timeout 75;
        types_hash_max_size 2048;
        server_tokens off;
        include /etc/nginx/mime.types;
        default_type application/octet-stream;
        proxy_read_timeout 600s;
        proxy_cookie_flags ~ secure httponly samesite=lax;
        ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3; # Dropping SSLv3, ref: POODLE
        ssl_prefer_server_ciphers on;
        gzip off;
        large_client_header_buffers 6 64k;

        upstream app_server {
                keepalive 60;
                server 127.0.0.1:8080 fail_timeout=0;
        }

        server {
                listen 443 ssl so_keepalive=on;

                include snippets/self-signed.conf;
                include snippets/ssl-params.conf;

                server_name my_server_domain;

                if ($request_method !~ ^(GET|HEAD|POST)$) {
                        return 444;
                }

                # just removing /answers prefix on URL as that's how request arrives from downstream
                rewrite ^/answers(.*)$ /$1 last;

                location / {
                        proxy_pass http://app_server;
                        proxy_buffering off;
                        proxy_redirect off;
                        proxy_http_version 1.1;
                        proxy_set_header Upgrade $http_upgrade;
                        proxy_set_header Connection "upgrade";
                        proxy_set_header Host $host;
                        # proxy_set_header X-Forwarded-Host $host;  #cannot use: "Connection Errorred out"
                        proxy_set_header X-Forwarded-Proto $scheme;
                        proxy_hide_header Access-Control-Allow-Origin;
                        proxy_connect_timeout 60s;
                        proxy_send_timeout 60s;
                        proxy_read_timeout 60s;
                }
        }
}

Screenshot

Logs

App log:
Dec 17 09:41:27 ... "GET /app/gradio_api/heartbeat/2pu0j9q9bc9 HTTP/1.1" 200 OK
So it seems the heartbeat is successfully done by the app.

NGINX Access log:
[17/Dec/2024:09:42:31 +0200] "GET /answersapp/gradio_api/heartbeat/2pu0j9q9bc9 HTTP/1.1" 200 54 "https://my_server_domain/app/" "Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Mobile Safari/537.36"

There's nothing in the NGINX error log, only the above line in the Access log. I do notice the URL seems invalid here, should be /answers/app/gradio_api/heartbeat/2pu0j9q9bc9 or /app/gradio_api/heartbeat/2pu0j9q9bc9 depending on whether it's before the URL rewrite or after.

System Info

Gradio Environment Information:
------------------------------
Operating System: Linux
gradio version: 5.8.0
gradio_client version: 1.5.1

------------------------------------------------
gradio dependencies in your environment:

aiofiles: 23.2.1
anyio: 4.7.0
audioop-lts is not installed.
fastapi: 0.115.6
ffmpy: 0.4.0
gradio-client==1.5.1 is not installed.
httpx: 0.28.1
huggingface-hub: 0.26.5
jinja2: 3.1.4
markupsafe: 2.1.5
numpy: 2.2.0
orjson: 3.10.12
packaging: 24.2
pandas: 2.2.3
pillow: 11.0.0
pydantic: 2.10.3
pydub: 0.25.1
python-multipart: 0.0.19
pyyaml: 6.0.2
ruff: 0.8.2
safehttpx: 0.1.6
semantic-version: 2.10.0
starlette: 0.41.3
tomlkit: 0.13.2
typer: 0.15.1
typing-extensions: 4.12.2
urllib3: 2.2.3
uvicorn: 0.32.1
authlib; extra == 'oauth' is not installed.
itsdangerous; extra == 'oauth' is not installed.


gradio_client dependencies in your environment:

fsspec: 2024.10.0
httpx: 0.28.1
huggingface-hub: 0.26.5
packaging: 24.2
typing-extensions: 4.12.2
websockets: 14.1

Severity

I can work around it