Piik/docs/deployment.md

Minimal Deployment

Last verified against upstream documentation: 2026-08-22.

This page records exact release 9461e20 production facts and the current source deployment contract. Product direction and pending migrations are owned by project memory and the TODO ledger.

This section documents the repository's UDP-only deployment candidate: one Node.js process provides the built Web client, room API, and WebSocket signaling behind Caddy or nginx; application ICE advertises only STUN by default; LiveKit supplies bounded SFU fallback capacity. Normal media remains distributed through direct or peer edges whenever those paths work.

A deployment may additionally provide one dedicated single-node LiveKit process as the current controller's automatic final media fallback. This capacity is dormant unless the complete public URL, private API URL, key, secret, and capacity tuple is configured. It does not replace the P2P path, the peer-assisted experiment, or required STUN discovery. LiveKit remains ICE/UDP only. Source no longer contains the rejected participant-wide Peer ICE TURN candidate; stale PEER_ICE_TURN_* keys fail startup even when blank. The selected-edge source tuple is enabled in production only for the controller's single exceptional edge. Production ordinary peer ICE remains STUN-only and the tracked coturn example remains stun-only; the shared host retains its older authenticated-relay daemon configuration and firewall range. The application does not pre-advertise TURN credentials to ordinary peers.

Production currently runs exact 9461e207af62b4f38f6b7a8aa16f8beb49e0e4ee from /opt/screener/releases/9461e20; immediate rollback is /opt/screener/releases/21d5cd9f7139. Local and public health return 200; Screener, LiveKit, coturn, and nginx are active, and Screener reports NRestarts=0.

The current release deploys the bounded pre-share health/WSS/STUN self-check, privacy-safe click-only diagnostic JSON export, room admission default eight with explicit limits from one through sixteen, bounded signaling-partition recovery, and peer-quality MBB. An ordinary Viewer with a peer/SFU upstream or the Host may own one separately budgeted provisional child. The endpoint-cap environment is unset, so the production default yields Host two and ordinary Browser Viewer one; the wire remains unchanged. The retained capacity-two/cap3 sixteen-Viewer and resource runs are historical ordinary-PC experiments only and do not define release policy or close performance gates. The release also deploys the identity-bound relayed-detail presentation, root <=2 controller/token invariant, Host-publication edge accounting, zero-child assignment/subscriber retention, and dynacast: false with ordered active q,h. These are bounded control-plane and publisher-configuration guarantees; real shaped LiveKit packet flow, BWE downshift/recovery, and resource cost remain open.

Topology and prerequisites

Use two DNS names, for example share.example.com and stun.example.com. They may resolve to the same public IP: the Web ingress owns TCP 443 while the self-hosted STUN listener owns UDP 3478.

browser -- HTTPS/WSS --> Caddy or nginx :443 --> Node.js :8787
browser <------------ DTLS-SRTP P2P ------------> browser
browser -- STUN binding/UDP --> coturn :3478 (application advertises STUN only)
browser <---------- DTLS-SRTP/UDP ----------> LiveKit :7882

The minimum runtime is Node.js 24 LTS and coturn 4.17.2 or a newer patched release. Provision a valid TLS certificate for the Web name. Enable operating system time synchronization and keep the Node application port reachable only from its reverse proxy. A single Node process is intentional. Active participants and signaling remain in memory; an optional protected SQLite file can restore room identity after a restart, but it does not restore live WebRTC connections.

Build and validate the exact revision on a build host before starting it:

npm ci
npm run check
npm start

Do not run the repository full check, typecheck, or build on the current 960 MiB no-swap production host. An inactive-release check before the 261e980c cutover temporarily starved HTTP and SSH; exact 691863e remained current and all four services stayed at NRestarts=0. The retained production path uses a locally verified dist artifact plus one npm ci --omit=dev in a transient unit bounded to 30% CPU, 160 MiB memory high, 256 MiB memory max, and 120 seconds. It then runs only runtime imports, node:sqlite, and artifact/inode/permission gates.

Each immutable release must own an independent dependency tree. Never hard-link node_modules or another file that deployment may chown, chmod, replace, or remove: metadata changes would also mutate the rollback release. A copy or copy-on-write reflink is acceptable only after an inode audit confirms that the old and new regular-file sets have zero shared inodes. Do not recursively change permissions until that check passes.

Transport archives must preserve UTF-8 entry names. Prefer the POSIX release archive path and verify the extracted manifest before switching. A Windows ZIP used for the 2026-08-20 route-rescue release altered two non-runtime Chinese documentation names on Linux. Runtime artifacts were unaffected and the immutable upload remains evidence, but do not reuse that packaging method.

In a strict-shell deployment, expected service states are data, not command failures. Do not call systemctl is-active bare under set -e/ERR: an intentionally stopped service returns a nonzero status and can trigger a false rollback. Read ActiveState with systemctl show, compare the returned string explicitly, and keep stop, symlink switch, start, health check, and rollback as separate steps. Preflight every inspection dependency before taking a backup or changing a service. If a host lacks the sqlite3 CLI, use the pinned Node runtime's node:sqlite API or stop before the first write. After a start, poll health for a short bounded window instead of treating one request during startup as a failed release; retain the last failure while still enforcing the deadline.

Run npm start under a service supervisor that injects the environment, restarts on failure, and applies bounded logs. For a simple untracked environment file, the equivalent direct launch is node --env-file=.env.production dist/server/server/index.js. Do not expose port 8787 to the Internet. The application default is 0.0.0.0 for LAN development and container compatibility, while the bare-metal production baseline below explicitly sets LISTEN_HOST=127.0.0.1 because only the same-host reverse proxy should connect. A container can instead use 0.0.0.0 and enforce the intended boundary with port publishing rules or a host firewall.

The optional same-host LiveKit layout needs no additional public hostname: LIVEKIT_URL=wss://share.example.com and nginx proxies only current /rtc/v1* requests to LiveKit. Retired /rtc and /rtc/validate endpoints return 404 without request-target logging. LiveKit's HTTP/WebSocket listener on TCP 7880 is private to nginx and the Screener process uses LIVEKIT_API_URL=http://127.0.0.1:7880 for RoomService; WebRTC media reaches LiveKit directly on UDP 7882. No unrelated application may create rooms on this instance, and its tracked configuration sets room.auto_create: false.

Candidate boundary and rollback

The accepted target for share.bonfire.icu remains distributed and automatic: direct/peer UDP first, with one Host publication available to authorized SFU subscriptions when a logical edge cannot use peer transport. SFU-fed and peer-fed endpoints use the same provisional-child transaction, and the exact candidate child's first newly decoded frame commits that edge. Server-assisted subscriptions and allocations use independent deployment admission rather than an endpoint-cap or fixed-root rule.

The repository requires STUN and ordinary peer connections receive STUN-only ICE. An existing logical edge prefers direct/peer UDP and may use exact selected TURN when configured; only an unavailable logical ingress uses the Host publication/SFU path. A Host-SFU ingress may itself use selected TURN. LiveKit participants receive only revision-bound sfu-config URL/token messages and negotiate within LiveKit's separate ICE domain. The selected-edge TURN config/wire is deployed in the current 9461e20 release with one UDP URL and a 120-second credential TTL. It was not exercised by a real media session during this cutover.

PEER_ASSISTED_MEDIA=true is the process-wide topology/SFU switch. Every normal room gets its own bounded controller state; ordinary peer connections remain STUN-only and only the selected-edge source path may grant TURN to the controller's then-current edge. Run candidate releases on an isolated instance/hostname and keep the old release unchanged for rollback. If the candidate fails, roll back the release or instance; do not add a permanent dual-transport branch.

A shared-public-IP instance can test candidate behavior while the old TURN service stays live, but it cannot prove the clean-port boundary or approve broad migration. The room-1 smoke uses this shape: nginx owns 443, LiveKit 1.13.5 owns UDP 7882, Peer ICE TURN is disabled, and LiveKit is fail-closed under a 192 MiB high/256 MiB hard cgroup limit with restart disabled. Prefer a separate VM/IP for the full gate and verify representative external networks and devices.

TURN REST authentication proves only HMAC and expiry to coturn. Coturn cannot verify a room, route, edge, or connection generation, so the application must bind issuance and parent/child rebuild to the current controller state, keep the attempt one-use and short-lived, and revalidate every asynchronous boundary. Never describe coturn itself as cryptographic selected-edge enforcement. HTTPS/WSS always remains TLS/TCP independently.

The 2026-08-20 exact-room canary used source a11a73dfa79d, inactive release /opt/screener/releases/a11a73dfa79d-r4, artifact SHA-256 C954185869A3A15CCCE642AB72A4CF90770476C117D61182D7728280C30A036F, and backup /opt/screener/backups/turn-a11-20260820T065933Z. The candidate switch completed at 14:59:33 +08. Local authenticated coturn allocation and application/deployment gates passed, but the real direct Host plus Pion Viewer did not establish its peer connection. The forced-relay test was therefore not run. Issuance was removed first, then coturn and its firewall rules returned to the pre-canary authenticated-relay baseline: TCP/UDP 3478 and UDP 49152-49251. Exact 7fea60ef6f2ad14a9ac1c23a89a523d91bbb97e4 was restored and advertises no TURN credential. The final lock-free check at 15:12:40 +08 found active services, zero allocations, and matching health, configuration, firewall, and SQLite state. No canary test process, browser profile, or transient firewall rule remained. The retained release is inactive. This is a canary no-go, not TURN deployment or media evidence. Two earlier attempts changed no durable state: one stopped before backup/write because sqlite3 was absent, and one rolled back after a single health request landed in the normal startup window. The preflight and bounded-poll rules above are the retained fixes.

Production application environment

Keep the real values in the process secret store or an untracked, access-restricted environment file. Node.js 24 can load such a file with --env-file; the tracked .env.example is only a schema. Generate independent secrets with a password manager or a cross-platform Node command such as:

node -e "console.log(require('node:crypto').randomBytes(32).toString('base64url'))"

Use this next-release baseline for the current source candidate:

NODE_ENV=production
LISTEN_HOST=127.0.0.1
PORT=8787
PUBLIC_BASE_URL=https://share.example.com
ALLOWED_ORIGINS=https://share.example.com
SITE_ACCESS_PASSWORD=<INDEPENDENT_8_TO_128_BYTE_ACCESS_KEY>
ROOM_DATABASE_PATH=/var/lib/screener/rooms.sqlite
ROOM_TTL_SECONDS=14400
MAX_ROOMS=1000
MAX_VIEWERS_PER_ROOM=8
ENDPOINT_MEDIA_COPY_CAPACITY=2

STUN_URLS=stun:stun.example.com:3478

To make automatic SFU fallback capacity available, add the complete tuple:

PEER_ASSISTED_MEDIA=true
LIVEKIT_URL=wss://share.example.com
LIVEKIT_API_URL=http://127.0.0.1:7880
LIVEKIT_API_KEY=<GENERATED_LIVEKIT_API_KEY>
LIVEKIT_API_SECRET=<INDEPENDENT_SECRET_OF_AT_LEAST_32_BYTES>
SFU_INGRESS_CAPACITY=<MEASURED_DEPLOYMENT_INGRESS_COPIES>
SFU_EGRESS_CAPACITY=<MEASURED_DEPLOYMENT_EGRESS_COPIES>

To enable exact selected TURN after bounded peer and SFU recovery, add its complete tuple:

SELECTED_EDGE_TURN_URLS=turn:turn.example.com:3478?transport=udp
SELECTED_EDGE_TURN_SHARED_SECRET=<INDEPENDENT_SECRET_OF_AT_LEAST_32_BYTES>
SELECTED_EDGE_TURN_CREDENTIAL_TTL_SECONDS=120
SELECTED_EDGE_TURN_ALLOCATION_CAPACITY=<MEASURED_DEPLOYMENT_ALLOCATIONS>

The rejected PEER_ICE_TURN_* participant-wide tuple is removed; supplying any stale key, even blank, fails startup. Current source requires the complete four-value SELECTED_EDGE_TURN_* tuple with one explicit TURN/UDP URI, an independent secret, bounded TTL, and positive safe-integer logical-allocation capacity. Each exact peer-selected edge and Host-SFU ingress consumes one unit from the same process ledger before credential issuance; reserved, committed, and draining authorizations stay charged until exact logical release. The production release remains on its recorded configuration until the four-value tuple is supplied atomically with current source. Only a controller-selected edge may receive a short-lived grant. Roll back by removing the application tuple before changing coturn or firewall state. Credentials never enter URLs, logs, browser persistence, room rows, or SQLite.

Application release does not prove deletion of the matching physical coturn allocation. Keep the credential TTL short and configure coturn user-quota and total-quota to bound allocations left by disconnect or process restart. A restarted single process begins a fresh logical ledger while old physical allocations expire under those coturn bounds; do not claim cross-restart reconstruction or per-allocation readback.

Before a media canary, npm run gate:turn-udp-allocation provides the bounded UDP allocation check. It proves only that an authenticated relay candidate can be allocated over UDP; it does not prove a media route, recovery, quality, or performance. Set CHROME_PATH in the process environment and supply the complete selected-edge tuple either in that environment or as newline-delimited KEY=value records on stdin. Values containing = are preserved. The script uses an isolated Chrome profile and loopback-only in-memory credential response, then emits only status, relay-candidate count, transport protocol, and coarse ICE error-code buckets. Do not echo, log, or persist raw production environment input; never add TURN URLs, usernames, credentials, candidate addresses, or raw errors to the result.

PEER_ASSISTED_ROOM_IDS is retired. Supplying it, even blank, fails startup so that a stale room-1 deployment cannot silently retain the old scope. With PEER_ASSISTED_MEDIA=true, every normal room receives peer-assisted routing, optional LiveKit fallback, and the same deployment resource/fanout/failure guards. Every ordinary peer connection remains STUN-only; selected-edge TURN is still issued only to a current controller-selected edge. There is no browser control, percentage rollout, or second router.

ALLOWED_ORIGINS must list exact http or https origins, never *. SITE_ACCESS_PASSWORD is required in production and must contain 8 through 128 visible ASCII bytes (0x21 through 0x7e). It must not be reused for LiveKit, TLS, TURN, or another service. It authorizes room creation, Host role, and code-only Viewer attempts; it does not replace a private room grant or password. Local development and tests may omit it. Supplying a removed access key, even blank, fails startup. ROOM_DATABASE_PATH is optional but requires SITE_ACCESS_PASSWORD. Omit the database path to keep random temporary rooms; ROOM_TTL_SECONDS applies only to those rooms. MAX_VIEWERS_PER_ROOM defaults to 8 and accepts 1 through 16. It is an admission limit, not evidence that the publisher can sustain that many streams. ENDPOINT_MEDIA_COPY_CAPACITY defaults to 2 and accepts only 1, 2, or 3. It is the single server-authoritative steady outbound media-copy cap for Host and Viewer endpoints; role, browser, UA, and visibility do not create another tier. A peer child or the Host's single SFU publication consumes one copy, upstream receive is free, a committed selected TURN transport for the same child does not consume a second copy, and an uncommitted selected carry does. Transition work may reach only min(C + 1, 3). A Host already sending three copies at C=3 must fail or wait before a fourth endpoint copy is issued; changing an existing copy to selected TURN remains the same endpoint copy and separately requires TURN allocation admission. Supplying the removed MAX_PEER_RELAY_DOWNSTREAM_EDGES, even blank, fails startup.

Production release 9461e20 still runs the legacy Host-2/Browser-1 policy on wire screener-v5. Deploy the current source server, Web assets, and Native sender atomically on screener-v6; restore the exact prior environment and release together when rolling back.

The four LIVEKIT_* values must either all be absent or all be present, and a complete tuple requires PEER_ASSISTED_MEDIA=true plus explicit positive safe-integer SFU_INGRESS_CAPACITY and SFU_EGRESS_CAPACITY values. The two capacities have no defaults and must be selected from the instance's measured publisher/subscriber/bitrate and accepted concurrency matrix. Supplying either capacity without the complete fallback configuration fails startup rather than silently enabling or ignoring a partial policy. An empty tuple with neither capacity keeps the optional SDK and server path dormant. LIVEKIT_URL must be a plain ws: or wss: origin with no /rtc suffix; production requires wss:. LIVEKIT_API_URL must be a plain http: or https: origin with no path; production permits plaintext only on loopback and otherwise requires https:. LIVEKIT_API_SECRET must contain at least 32 bytes and must not reuse SITE_ACCESS_PASSWORD. These credentials authorize short-lived LiveKit room tokens and do not provide E2EE: the LiveKit operator can access ordinary SFU media. The LiveKit instance is dedicated to this Screener process and has room.auto_create: false. Screener first binds the configured application listener exclusively; a competing process that cannot bind makes no LiveKit call. While bound but not initialized it returns 503 and has no signaling upgrade handler. It then rejects any foreign room name, deletes every stale managed room, confirms the namespace empty, and begins serving. Each exact-generation room is then created before its token is issued. Reserved, committed, and draining generations remain charged until DeleteRoom succeeds and a follow-up lookup proves absence. Run only one application process until a shared atomic admission and lifecycle owner exists.

For the first candidate canary, use an isolated instance and a protected persistent room whose ID is stable across restarts. Restart the application and verify startup removes a seeded stale managed LiveKit room before serving traffic. Hold the application port with another process and verify a competing startup makes zero LiveKit calls. Verify that both the persistent room and a second normal room contain mediaMode: "peer-assisted", with independent route revisions and no shared room state or capacity bypass. Exercise join, offer and answer, stale-token reconnect after abort, Host signaling loss with and without a live Host participant, stop, restart, and room deletion in both rooms. Confirm each drain keeps capacity charged until the room is absent. Ordinary Web and Native-shaped clients remain STUN-only. With the selected-edge tuple, only the current controller-selected edge may receive a one-use grant; all other sessions and connections remain STUN-only. Roll back by disabling application issuance, stopping Screener, and proving every managed LiveKit room absent before restoring the exact recorded application/LiveKit configuration and release; or direct traffic to the unchanged old instance. Restore the coturn/firewall baseline only after the application no longer issues its selected-edge grant. Do not treat disabling PEER_ASSISTED_MEDIA alone as TURN rollback: disable the selected-edge tuple independently, and no removed old TURN wire is restored. During migration, remove the retired room-ID variable in the same coherent change; the process flag explicitly enables the all-room controller.

Only POST /api/site-access accepts the site access secret in an Authorization: Bearer header from an exact allowed Origin. Success returns a 12-hour stateless HMAC-SHA256 cookie with HttpOnly, SameSite=Strict, Path=/, bounded Max-Age, and, under production HTTPS, Secure plus an __Host- name. The cookie contains no account or server-side session ID. There is no account database, JWT, session map, or logout endpoint.

Before an access-boundary release, set CHROME_PATH to a local Chrome or Chromium executable and run npm run gate:access-privacy. The gate creates only a loopback room and temporary SQLite/profile state, navigates the fragment through CDP rather than a process argument, disposes its ephemeral browser context, and emits only fixed booleans and counts. It also checks the tracked nginx logging shape and runs the complete signaling suite containing the strong rotate/revoke teardown case. The room password enters only at the RoomStore boundary, so this run proves its raw SQLite non-persistence, not its WebSocket or log ingress. It never connects to production or accepts a production credential; exact production request/nginx/journal/database inspection remains separate.

nginx limits this exact endpoint per source at 5r/m with burst=5 nodelay and returns 429 when exhausted. The limiter uses nginx shared memory; do not add the secret, Authorization header, request body, or a new source-address field to logs. POST /api/rooms accepts only the site-access cookie and strict JSON with an explicit Viewer policy; a Bearer header is not an alternate creation path. /signal still admits a cookie-free browser after Origin and capacity checks and records the cookie state at upgrade. Host requires it with the room Host token. A Viewer may omit it only when presenting a valid, unexpired grant for that exact room; otherwise the server rejects before evaluating public-watch or a room password.

Private rooms are the default. Their invitation is /r/{code}#v={room-scoped-grant}; the fragment does not enter HTTP or WebSocket request targets. The page validates it, writes it only to that room's sessionStorage, and immediately replaces the visible URL with /r/{code}. An independent tab without the fragment must first pass site access. A private room then requires its room password, while explicit public-watch accepts the numeric room code. Neither policy lets a Viewer create a room or authenticate as Host.

Room allocation has two deliberately small policies:

• With ROOM_DATABASE_PATH, SQLite allocates positive decimal IDs starting at 1. These rooms do not expire, while each private Viewer invitation expires after seven days unless rotated earlier. An explicit stop or capture track ending stops the current publication and leaves viewers waiting; it does not delete the room. A brief signaling disconnect does not stop otherwise healthy P2P media.
• Without ROOM_DATABASE_PATH, rooms use random numeric IDs and expire according to ROOM_TTL_SECONDS; a private grant cannot outlive its room. Stopping sharing does not immediately delete it. Public-watch remains available but explicit.

The built-in node:sqlite schema v3 stores each room ID, a SHA-256 Host token digest, one nullable SHA-256 Viewer-grant digest, and optional validated Viewer password material in the same STRICT row. NULL means public-watch or no password; checked BLOBs mean private-link/password state. It must not contain plaintext tokens or grants, passwords, cookies, names, participants, SDP, ICE candidates, IP addresses, TURN credentials, or media. Protect and back up the file as service state. The tracked systemd unit creates /var/lib/screener with StateDirectory=screener and mode 0700; the production path above is writable despite ProtectSystem=strict. The database is designed for one application process, not shared storage across multiple instances.

For a simple consistent backup, stop screener.service before copying the SQLite file, then start it again. Restore while the service is stopped, restore ownership to the service account and mode 0600, run SQLite PRAGMA integrity_check, and only then start the service. An online backup must use SQLite's backup API or VACUUM INTO; do not copy only the live main file while it may have an active journal.

The current release migrates schema v1 or v2 to v3 and has no dual-schema runtime. For an existing deployment, stop the service and take a named, immutable copy before installing or starting the new binary. Confirm the stopped source reports PRAGMA user_version = 1 or 2, retain the backup outside the release directory, and record its checksum. On first v3 startup, one BEGIN IMMEDIATE transaction first gives v1 rows a checked nullable Viewer grant digest with a fresh fail-closed value, then gives v1/v2 rows the checked nullable password material and advances user_version to 3.

After startup, verify PRAGMA integrity_check, user_version = 3, service health, Host reclaim, invitation rotation, password update/removal, and a new Viewer join before removing the maintenance boundary. If rollback is required, stop the v3 service, preserve the v3 database separately for diagnosis, restore the exact pre-migration backup with service ownership and mode 0600, verify its integrity and original user version, and only then start the matching old binary. Never point an old binary at the migrated v3 file.

Enabling persistence does not migrate rooms that existed only in memory. The deployment restart invalidates those temporary links; the first subsequently created persistent room receives ID 1.

Production startup requires one to eight syntactically valid stun: URLs before the server listens. This validates shape only; it does not prove DNS, firewall, NAT mappings, or external STUN reachability. The current application rejects TURN_URLS, TURN_SHARED_SECRET, or TURN_CREDENTIAL_TTL_SECONDS when any key is present, including with an empty value. Remove those obsolete keys from the candidate environment; startup fails instead of pretending they enable compatibility.

The rejected candidate names PEER_ICE_TURN_URLS, PEER_ICE_TURN_SHARED_SECRET, and PEER_ICE_TURN_CREDENTIAL_TTL_SECONDS must remain absent from production and now fail startup even when blank. They are not aliases for the selected-edge tuple; ordinary peer edges remain STUN-only while only the current controller edge may use the configured selected-edge transport.

HTTPS and WSS ingress

Terminate public TLS at Caddy or nginx and proxy every application path to the single Node process. /signal must preserve the WebSocket upgrade, Host, and Origin, and its idle/read timeout must be longer than a normal sharing session. Do not cache /api/* responses. Caddy's minimal same-host form is:

share.example.com {
    reverse_proxy 127.0.0.1:8787
}

An equivalent nginx location is:

location / {
    proxy_pass http://127.0.0.1:8787;
    proxy_http_version 1.1;
    proxy_set_header Host $host;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_read_timeout 1h;
}

The tracked share.bonfire.icu.conf.example follows this simple model and listens directly on public TCP 443. It does not need an SNI transport router. Exact /rtc and pinned-v0 /rtc/validate requests return 404 with access and request-line error logging disabled; only /rtc/v1* is proxied. Current versioned requests carry a short-lived LiveKit JWT in the query string, so no /rtc* target may fall through to the site's ordinary logs.

When Certbot manages the Web certificate, install the tracked reload-nginx.sh as an executable under /etc/letsencrypt/renewal-hooks/deploy/. Run certbot renew --dry-run after the first certificate is installed. This hook reloads only the Web ingress.

Keep the proxy's access-log retention bounded and access controlled. Requests to /r/{code} put the room code in the path, so access logs can contain room codes as well as network metadata. They must not be treated as public artifacts. For a private room, the grant remains in the fragment and is not part of that request target. A public-watch code still requires prior site access.

For a process-level liveness probe, send GET /healthz. A running process returns HTTP 200 with {"status":"ok"} and Cache-Control: no-store; other methods return 405 with Allow: GET. The endpoint does not inspect room state, STUN/SFU reachability, or any external dependency, so use it only to decide whether the Node process can accept HTTP requests. It is not a deployment-readiness or end-to-end media check.

Optional single-node LiveKit fallback

Use the tracked livekit.yaml.example and livekit.service.example as the minimal single-node baseline. Install a reviewed, pinned LiveKit Server release from its official release assets, generate an independent key pair with livekit-server generate-keys, and place only the YAML key mapping in /etc/livekit/keys.yaml. Keep that file owned by the livekit service account with mode 0600; put the same values in Screener's untracked process secrets.

The example deliberately omits Redis and every recording, ingress, egress, webhook, external-TURN, and embedded-TURN service. It explicitly sets tcp_port: 0 and allow_tcp_fallback: false, and points stun_servers at the deployment's self-hosted STUN listener so pinned LiveKit cannot inherit its default public Google STUN servers. Do not add Redis for this one-node workload. The service journal is the diagnostic log; keep its retention finite and access restricted. Never enable debug/Pion packet logging continuously or persist JWTs, SDP, ICE candidates, API secrets, or full /rtc and /rtc/* request targets.

Configure both the host firewall and the provider firewall independently:

Destination	Protocol	Exposure	Purpose
127.0.0.1:7880	TCP	Private	nginx to LiveKit signaling/API
public host :7882	UDP	Public	WebRTC ICE/UDP mux

LiveKit may listen beyond loopback while it discovers and advertises public media addresses, so the public-firewall denial of TCP 7880 is mandatory; nginx must be its only ingress. UDP 7882 is a direct media listener and must not be placed behind the HTTP reverse proxy. If the host is behind NAT, forward it without port translation and verify the advertised candidate from an external network. UDP-blocked networks are expected to fail clearly in this candidate; do not set rtc.tcp_port above zero, enable TCP fallback, or add TURN to make a canary pass silently.

Self-hosted STUN

This subsection describes the temporary STUN-only deployment template, not the enabled selected-edge production environment or the current shared-host coturn state. That host retains an older authenticated-relay configuration and TCP/UDP 3478 plus UDP 49152-49251 firewall range. In this template Screener advertises no TURN credential and the canary audit found zero allocations; production selected-edge issuance remains limited to the controller's one configured edge and has one active Host-ingress forced-relay functional acceptance. Initial Host ingress and peer-selected last mile remain open.

Copy deploy/coturn/turnserver.conf.example to an untracked service-owned location and use the tracked coturn.service.example. The config uses coturn's documented stun-only mode, ignores every TURN allocation request, and disables TCP and TLS client listeners. It has no auth secret, user database, relay port range, certificate, quota, or TURN REST credential. Pinned coturn 4.17.2 deprecates no-dtls, so the tracked config does not use that obsolete switch or claim a separate DTLS listener gate.

On a single-homed public host, automatic listener selection is sufficient. On a multi-homed host, set listening-ip to the intended public interface. Open only UDP 3478 and keep TCP 3478/5349 plus every old relay range closed. The same public IP may serve HTTPS/WSS on TCP 443 and LiveKit media on UDP 7882.

The example writes informational logs to stdout. Apply finite supervisor retention and restrict access because STUN sees client IP addresses. Do not enable verbose or log-binding continuously. stun-only is a hard candidate boundary, not a hidden unauthenticated TURN service.

Open only these public listeners:

Destination	Protocol	Purpose
share.example.com:443	TCP	HTTPS and WSS
stun.example.com:3478	UDP	STUN binding only
host public address :7882	UDP	LiveKit WebRTC ICE/UDP mux

Verification

Run these checks from real external networks before calling the deployment usable:

1. Open the official Trickle ICE sample and test the configured STUN URL. It must produce an srflx candidate over UDP and no relay candidate. Confirm TCP 3478/5349 and the old relay range are closed externally.
2. Create a normal Screener room on two different networks. Confirm media flows and the selected-pair stats report a non-relay path when direct ICE succeeds.
3. On a normal room, exhaust a peer route and verify exactly one Host publication serves only the admitted SFU subscriptions over LiveKit UDP 7882. Peer descendants stay on ordinary direct UDP and every non-server endpoint obeys the configured ENDPOINT_MEDIA_COPY_CAPACITY.
4. Force one controller-eligible edge past SFU/UDP and verify only that edge gets the short-lived TURN server plus relay policy and selects TURN/UDP. Ordinary peer PCs must stay STUN-only. Then block all UDP and verify bounded recovery ends clearly without ICE/TCP, TURN/TCP, or a long pseudo-connected path.
5. Exercise root departure, reconnect, SFU unavailable, route prepare rollback, stop, and source/profile changes. Unaffected subtrees must not migrate.
6. Repeat at 1, 3, 5, and 8 viewers across representative consumer networks. Record selected protocol, RTT, bitrate, frame rate, packet loss, publisher upload/encode load, LiveKit ingress/egress, and final decoded quality. A real 1:8 session remains unverified until this matrix passes.

References: coturn 4.17.2 release, pinned turnserver documentation, the pinned example configuration, RFC6265bis, LiveKit firewall guidance, and the pinned LiveKit configuration sample.