Revert \"Merge pull request #2578 from keboola/pepa/PAT-1538_e2bStreamlit\"

[devin-ai-integration]

Release Notes

Reverts #2578 — restores the Streamlit WebSocket Origin rewriting workaround in apps-proxy.

Plans for customer communication

None.

Impact analysis

PR #2578 removed a temporary workaround that rewrote the WebSocket Origin header to match the upstream hostname for Streamlit (Tornado) apps. The commit message claimed Streamlit apps were now configured with STREAMLIT_BROWSER_SERVER_ADDRESS / STREAMLIT_BROWSER_SERVER_PORT env vars, but these env vars were never actually configured anywhere.

This caused Tornado to reject WebSocket connections with 403 (Origin mismatch), breaking the /_stcore/stream endpoint across all stacks:

• /_stcore/stream 403s jumped from 0 → 31,803 in a 4-hour window
• Streamlit clients retry failed stream connections, amplifying total traffic ~3.5x
• /_stcore/health and /_stcore/host-config requests jumped from ~16k → ~56k per 4h
• Most affected environments: kbc-eu-central-1 (22,975 spans), cloud-keboola-groupon (17,243 spans)

This revert restores the Origin rewrite workaround until STREAMLIT_BROWSER_SERVER_ADDRESS / STREAMLIT_BROWSER_SERVER_PORT are properly configured on all Streamlit Data Apps.

Change type

Revert / bugfix

Justification

Production incident — Streamlit Data Apps broken across all stacks after v1.10.1 deployment.

Deployment

Merge & automatic deploy.

Rollback plan

Revert of this PR.

Post release support plan

None.

Link to Devin session: https://app.devin.ai/sessions/a88bf1485da340738418021851aadc44

[devin-ai-integration]

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[linear]

PAT-1538 [streamlit] Behind proxy setup