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…for proxy chain SSE connections through Cloudflare → Envoy → Node.js are killed after ~125s of idle time. This adds two fixes: 1. SSE heartbeat: sends `: ping\n\n` comments every 30s (configurable via GITLAB_SSE_HEARTBEAT_MS) to keep connections alive through proxies. Applied to both legacy /sse and modern StreamableHTTP GET endpoints. 2. HTTP server timeouts: configures keepAliveTimeout (620s), headersTimeout (625s), and timeout (0) to prevent Node.js from closing connections before upstream proxies do. Configurable via GITLAB_HTTP_KEEPALIVE_TIMEOUT_MS. Closes #139
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Pull request overview
This PR addresses a critical production issue where SSE connections through proxy chains (Cloudflare → Envoy → Node.js) are killed after approximately 125 seconds of idle time. The fix implements two complementary solutions: SSE heartbeat keepalives and proper HTTP server timeout configuration.
Changes:
- Added configurable SSE heartbeat mechanism sending
: ping\n\ncomments every 30 seconds to keep connections alive through proxies - Configured HTTP server timeouts (keepAliveTimeout=620s, headersTimeout=625s, timeout=0) to prevent Node.js from closing connections before upstream proxies
- Applied heartbeat to both legacy
/sseendpoint and modern StreamableHTTP GET endpoints with proper cleanup on connection close
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/config.ts | Added SSE_HEARTBEAT_MS and HTTP_KEEPALIVE_TIMEOUT_MS configuration with environment variable parsing and validation |
| src/server.ts | Implemented startSseHeartbeat() helper, configureServerTimeouts(), integrated heartbeat into both SSE endpoints, and switched to http.createServer() for timeout control |
| tests/unit/server.test.ts | Added 10 comprehensive unit tests covering heartbeat lifecycle, ping delivery, cleanup, and HTTP timeout configuration |
polaz
deleted the
feat/#139-fixtransport-add-sse-keepalive-and-configure-http
branch
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🎉 This PR is included in version 6.31.2 🎉 The release is available on: Your semantic-release bot 📦🚀 |
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Summary
: ping\n\ncomments every 30s) to keep connections alive through Cloudflare/Envoy proxy chains that kill idle SSE streams after ~125skeepAliveTimeout=620s,headersTimeout=625s,timeout=0) to prevent Node.js from closing connections before upstream proxiesGITLAB_SSE_HEARTBEAT_MSandGITLAB_HTTP_KEEPALIVE_TIMEOUT_MSenvironment variables/sseand modern StreamableHTTP GET endpointsChanges
src/config.ts— AddSSE_HEARTBEAT_MSandHTTP_KEEPALIVE_TIMEOUT_MSconfig with env var parsingsrc/server.ts— AddstartSseHeartbeat()helper,configureServerTimeouts(), integrate into both SSE endpoints, usehttp.createServer()for proper timeout controltests/unit/server.test.ts— 10 new tests covering heartbeat start/stop/ping, GET SSE streams, POST non-heartbeat, HTTP timeout configurationTest plan
DR(Downstream Reset) flags no longer appear at ~125sCloses #139