Streamlit app hit by 502 error
sandman2412
HOBBYOP

4 months ago

I've been trying to deploy a Streamlit app from a Docker container for several hours now only to be hit by a 502 Error:

requestId:
"pfcXMJG5SX6HfAr80-QtfA"
timestamp:
"2025-08-14T16:47:57.562384242Z"
method:
"GET"
path:
"/"
host:
"lumon-fund-bot-production.up.railway.app"
httpStatus:
502
upstreamProto:
""
downstreamProto:
"HTTP/2.0"
responseDetails:
"Retried single replica"
totalDuration:
146
upstreamAddress:
""
clientUa:
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36"
upstreamRqDuration:
4
txBytes:
4682
rxBytes:
937
srcIp:
"152.37.80.22"
edgeRegion:
"europe-west4-drams3a"
upstreamErrors:
"[{"deploymentInstanceID":"66cf260a-e6fc-43ff-b66b-d00e43686e91","duration":0,"error":"connection refused"},{"deploymentInstanceID":"66cf260a-e6fc-43ff-b66b-d00e43686e91","duration":0,"error":"connection refused"},{"deploymentInstanceID":"66cf260a-e6fc-43ff-b66b-d00e43686e91","duration":4,"error":"connection refused"}]"

My Dockerfile is below:

FROM python:3.12-slim

WORKDIR /app

# Install system dependencies
RUN apt-get update && apt-get install -y --no-install-recommends \
    rsync \
 && rm -rf /var/lib/apt/lists/*

# Install Python dependencies first
COPY docling/requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy all project files
COPY . .



ARG PORT=8080
EXPOSE ${PORT}

CMD streamlit run /app/docling/5-chat.py --server.address 0.0.0.0 --server.port $PORT

My railway.toml file is:

[build]
builder = "dockerfile"
dockerfilePath = "Dockerfile"

[deploy]
healthcheckPath = "/"
healthcheckTimeout = 300
restartPolicyType = "on_failure"

I'm using a Railway volume as I need to access data from persistent storage.

Can someone help here?

$10 Bounty

5 Replies

sandman2412
HOBBYOP

4 months ago

Here are the deploy logs which don't show any error:

Here's my Deploy logs:

Mounting volume on: /var/lib/containers/railwayapp/bind-mounts/66cf260a-e6fc-43ff-b66b-d00e43686e91/vol_r7rq2uik7u834q8n

Starting Container



Collecting usage statistics. To deactivate, set browser.gatherUsageStats to false.





  You can now view your Streamlit app in your browser.



  URL: http://0.0.0.0:8080
uxuz
MODERATOR

4 months ago

Hey @Sandip, have you checked the docs for possible solutions? Especially checking if the port is set correctly in the public networking section.

sandman2412
HOBBYOP

4 months ago

@uxuz Thanks, I managed to fix it by changing the custom port in the Networking section of settings! Now, however, I face a different problem: my app connects to a sqlite-like DB (called LanceDB) which I've copied over in the Dockerfile. I'm using a Railway Volume mounted at /data and copying over the data/ folder from my repo like so:

```RUN echo '#!/bin/bash\n\
if [ ! -f "/data/.initialized" ]; then\n\
echo "Copying database to persistent volume…"\n\
cp -r /app/data/* /data/ 2>/dev/null || true\n\
touch /data/.initialized\n\
fi\n\
exec streamlit run /app/docling/5-chat.py --server.address 0.0.0.0 --server.port ${PORT} --server.headless true\n\
' > /start.sh && chmod +x /start.sh

However, the app is unable to find the db files:

Failed to connect to database at /data/lancedb: Table 'portfolio' was not found

Make sure the database has been initialized by running the pipeline steps 1-3```

I'm unfortunately finding Railway quite opaque as it does not surface the Docker logs making it difficult to debug!

sandman2412
HOBBYOP

4 months ago

What I'm missing is direct SSH access to the container

brody
EMPLOYEE

4 months ago

railway ssh

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