stats: take per-track series from the relay, not /state

Both sources emitted moqx_track_subscribers, so leaving the /state module in
place would blend two label schemes into one metric name. The relay's own
counters are durable where /state's entries are transient (#501),
and they carry bytes and object counts /state never had.

Tracks table gains real Bitrate (ingest rate) and Data Tx (delivered payload).

Author: gmarzot

docker/json-exporter/json-exporter.yml

@@ -1,31 +1,15 @@
 # json_exporter config for the moqx stats stack.
 #
-# Turns the relay admin /state JSON (which the aggregate /metrics does NOT carry)
-# into per-track Prometheus series so Grafana can graph subscribers per track
-# over time. Prometheus scrapes this exporter with ?module=moqx&target=<state-url>
-# (see the moqx-state job in prometheus.yml).
+# Turns admin JSON the aggregate /metrics does not carry into Prometheus
+# series. Prometheus scrapes this exporter with ?module=<name>&target=<url>
+# (see the moqx-state and moqx-info jobs in prometheus.yml).
 #
-# NOTE: per-track series scale with the number of distinct track names, so this
-# is higher-cardinality than the relay's own metrics — scraped at 15s to keep
-# the sample rate down.
+# Per-track series come from the relay's own /metrics/track, not from here:
+# both emitted moqx_track_subscribers, and /state's entries are transient and
+# undercount under load (openmoq/moqx#501).
 modules:
   moqx:
     metrics:
-      # One series per active subscription entry, keyed by track name.
-      - name: moqx_track
-        type: object
-        help: Per-track subscription stats from the relay admin /state
-        path: '{.services.default.subscriptions[*]}'
-        labels:
-          track: '{.track_name}'
-          is_publish: '{.is_publish}'
-          # namespace is a JSON array (e.g. ["com.wowza","moq","moqtest_all"]);
-          # slash-join it into a browsable path label (separator between
-          # elements only — no trailing "/").
-          namespace: '{.namespace[0]}{range .namespace[1:]}/{@}{end}'
-        values:
-          subscribers: '{.subscribers}'
-          forwarding_subscribers: '{.forwarding_subscribers}'
       # Top-level scalars for cross-checking against the aggregate /metrics.
       - name: moqx_state_active_sessions
         help: Active sessions reported by the admin /state