Datarhei — Dragon Fork

A fork of datarhei/core that adds a native WebRTC (WHEP) egress path. Everything upstream Datarhei already does — RTMP / SRT / RTSP ingest, FFmpeg process orchestration, HLS / DASH outputs, S3 mounts, the HTTP API and Swagger UI — works unchanged. WebRTC sits alongside as another output type, opt-in per process.

publisher (OBS / FFmpeg / SRT) ──▶  datarhei Core  ──▶  WebRTC peers
            │                            │   (1–5 viewers per stream)
            │                            ├──▶ HLS / DASH (existing)
            │                            ├──▶ RTMP relay (existing)
            └──▶ ingest (RTMP / SRT / …) └──▶ recording (existing)

Sub-second glass-to-glass on a LAN over WHEP, no SFU dependencies, single binary, single Docker image.

Status: v0.2 in progress (last work 2026-05-06). Full GUI bundled (Restreamer UI + Wild Dragon WebRTC admin). Prometheus + Grafana observability stack shipped. Live deploy running on TrueNAS since 2026-04-17.

What this fork adds

• webrtc.* config block alongside rtmp.* and srt.*, with the same CORE_* env-var binding pattern.
• Per-process webrtc.enabled toggle on the existing process config. Once true, Core auto-injects two RTP output legs (video + audio), allocates UDP ports, and the WHEP endpoint is live.
• POST /api/v3/whep/{processID} — WebRTC-HTTP Egress Protocol subscribe; SDP offer in, SDP answer out. JWT-protected by the existing Core auth.
• DELETE /api/v3/whep/{processID}/{resourceID} — idempotent teardown.
• PATCH …/{resourceID} — trickle ICE.
• Bundled GUI — the upstream Restreamer React UI is built into the TrueNAS deploy image with Wild Dragon branding, plus a single-file Wild Dragon WebRTC admin page for one-click webrtc.enabled toggling.
• Browser-side smoke player at whep-player.html — zero-dependency WHEP subscriber, ICE/codec/bitrate stats, JWT field, shareable ?url=&token= URLs.
• Prometheus observability — eleven dragonfork_webrtc_* metrics (RED-method counters/histograms + state gauges). Grafana health dashboard with 5 rows and 4 pre-loaded alert rules.
• Multi-viewer correctness: per-stream peer cap, ICE-failure auto-cleanup, process-stop broadcast tear-down.
• Error matrix per the design spec: 406 on codec mismatch, 504 on ICE timeout, 503 on cap, 204 on idempotent DELETE, CORS preflights on every WHEP route.

The existing upstream Datarhei feature set is intact — see "From upstream Datarhei" below.

Quick start

Docker (TrueNAS / any host with Docker + LAN-reachable IP)

git clone https://forge.wilddragon.net/zgaetano/datarhei-dragonfork-core.git
cd datarhei-dragonfork-core/deploy/truenas/core

cat > .env <<EOF
PUBLIC_IP=10.0.0.25
CORE_HTTP_PORT=8080
API_AUTH_USERNAME=admin
API_AUTH_PASSWORD=$(openssl rand -base64 24)
API_AUTH_JWT_SECRET=$(openssl rand -base64 48)
GRAFANA_ADMIN_PASSWORD=$(openssl rand -base64 24)
GRAFANA_PORT=3000
PROM_PORT=9090
EOF

docker compose up -d --build

Then open in a browser (replace <host> with your PUBLIC_IP):

URL	What it does
http://<host>:8080/	Restreamer UI — manage processes, ingests, outputs
http://<host>:8080/wilddragon-webrtc.html	Wild Dragon WebRTC admin — toggle webrtc.enabled per process, copy WHEP URL
http://<host>:8080/whep-player.html	WHEP smoke player — verify the WebRTC stream renders
http://<host>:3000/	Grafana — WebRTC Health dashboard (login with GRAFANA_ADMIN_PASSWORD)
http://<host>:9090/	Prometheus — raw metrics, alert rules
http://<host>:8080/api/swagger/index.html	Swagger — full API docs

The Restreamer UI doesn't yet have a WebRTC checkbox in its process editor — use /wilddragon-webrtc.html for that. Tracked in issue #15.

Pulling a pre-built image (after first tag is published)

# Update .env, then:
docker compose pull   # pulls pre-built multi-arch image
docker compose up -d  # no --build needed

Sample process JSON

{
  "id": "live",
  "input": [
    { "address": "{rtmp,name=live.stream}", "options": [] }
  ],
  "output": [],
  "webrtc": { "enabled": true }
}

That's it. No webrtc:// URL scheme to learn — the toggle on config.webrtc.enabled is the entire surface. The resolver allocates ports, injects -f rtp udp://… legs into the FFmpeg command, and the WHEP endpoint at /api/v3/whep/live becomes live the moment the process starts.

For multi-input pipelines (lavfi test sources, multi-camera switches, SDI + file audio), use the video_map and audio_map fields:

"webrtc": {
  "enabled": true,
  "video_map": "0:v:0",
  "audio_map": "1:a:0",
  "force_transcode": true
}

Documentation

Topic	Where
Design spec	docs/design/2026-04-16-datarhei-dragon-fork-webrtc-design.md
M1 (PoC) plan	docs/design/2026-04-16-datarhei-dragon-fork-m1-webrtc-poc.md
M2 (Core integration) spec	docs/design/2026-04-17-datarhei-dragon-fork-m2-webrtc-core-integration.md
Prometheus metrics design	docs/design/2026-05-03-datarhei-dragon-fork-webrtc-prometheus-metrics-design.md
Upstream rebase policy	docs/REBASE.md
TrueNAS deploy guide	deploy/truenas/core/README.md
Testing	test/TESTING.md
Changelog (Dragon Fork)	CHANGELOG.md
Upstream Datarhei docs	docs.datarhei.com/core

Building from source

Go 1.24 required (vendored).

make release   # cross-compiles linux/amd64 to ./core/core
make test      # full suite, race detector
go test -tags latency -timeout 90s -count=1 \
  -run TestLatencyServerHop ./app/webrtc/...   # latency p95 gate

Load testing

go run ./test/load/sustained.go \
  -url http://<host>:8080 \
  -stream <processID> \
  -peers 5 \
  -duration 10m \
  -auth "Bearer <TOKEN>" \
  -out test/load/results/

Reports are written to test/load/results/. Observe the Grafana WebRTC Health dashboard during the run.

From upstream Datarhei

This fork preserves everything upstream Datarhei Core does — Dragon Fork is purely additive. If a feature isn't WebRTC-related, the behaviour is unchanged from upstream and the upstream documentation applies as-is.

Subsystem	Upstream feature set
Process management	API-driven FFmpeg, error detection / recovery, log history, resource limits, statistics, FFprobe input verification, process metadata
Media delivery	HTTP/S, RTMP/S, SRT services with Let's Encrypt, configurable file systems (in-memory / disk / S3), HLS/DASH session limits, viewer session API
Misc	HTTP REST + GraphQL, Swagger, Prometheus metrics, multi-arch Docker images

Attribution

Dragon Fork is built on:

• datarhei Core — Apache 2.0, © datarhei. The base repository this fork tracks. See NOTICE for the required attribution.
• datarhei Restreamer UI — Apache 2.0, © datarhei. The React frontend bundled into the TrueNAS deploy image with Wild Dragon overlays.
• Pion WebRTC — MIT. The Go WebRTC stack the egress path is built on.
• FFmpeg — LGPL / GPL (build-flag dependent). Used as a subprocess for transcoding and RTP packetisation; Dragon Fork doesn't link against it.

Full third-party credits in CREDITS.

License

Apache License 2.0 — same as upstream. See LICENSE.