domainsd-cpp (experimental)

domainsd-cpp is an experimental native local-domains proxy used by:

• f domains --engine native up
• f domains --engine native down

It is designed for low overhead on localhost routing and keeps Flow route state in:

• ~/.config/flow/local-domains/routes.json

Current scope:

• HTTP/1.1 host-based routing (*.localhost -> host:port)
• WebSocket upgrade passthrough (full duplex tunnel)
• request-side chunked transfer-encoding decode/forward
• upstream keepalive connection pooling (safe framed-response reuse)
• overload shedding with bounded active client handlers (503 when saturated)
• upstream connect/IO timeouts (504 for connect timeout)
• health endpoint: GET /_flow/domains/health
• mtime-based route reload (no daemon restart required)
• optional macOS launchd socket activation (--launchd-socket <name>) for privileged :80 bind without Docker

Runtime tuning:

• daemon supports CLI flags (--max-active-clients, --upstream-*-timeout-ms, --pool-*)
• Flow passes tuning via env vars prefixed FLOW_DOMAINS_NATIVE_*

Current limitations:

• no HTTP/2/TLS yet

The Flow CLI builds this binary automatically with clang++ when needed.

macOS native :80 without Docker

When direct bind to 127.0.0.1:80 is blocked by permissions, install launchd socket mode once:

sudo ./tools/domainsd-cpp/install-macos-launchd.sh

This installs dev.flow.domainsd in /Library/LaunchDaemons, binds port 80 via launchd, and runs domainsd-cpp as your user with inherited socket fd.

Uninstall:

sudo ./tools/domainsd-cpp/uninstall-macos-launchd.sh