Extended Prometheus metrics

Composer exposes roughly 160 metrics on its Prometheus endpoint (default port 8015, path /metrics). The tables below are the canonical reference, generated from the metric definitions in the engine; the Description column reproduces the # HELP text served alongside each metric on the endpoint. From R2 2026 every metric is emitted by every Composer build and licence tier (including Trial) with no separate activation.

Caution

Pre-R2 2026 releases: On older releases the extended metrics still appeared on the endpoint but reported 0 and didn't update unless the host's licence carried the Extended Monitoring plug-in entry (Trial builds were the exception and always exposed them). The baseline metrics (see below) have always reported normally regardless of licence.

Naming and prefixes

Metric names are a wire contract — Grafana dashboards and alert rules query them by name, so they are stable across releases. Composer uses five name prefixes:

Prefix	Group	Notes
`composer_`	Baseline	Core render-loop and log counters. Always emitted on every tier.
`composer_ext_`	Extended	The bulk of the surface — GPU, RTMP/SRT, alarms, WebSockets, etc. The `_ext_` prefix is historical; it is not a reliable marker of which group a metric belongs to.
`composer_packager_sink_target_`	MoQ / Packager target	Per-target media-over-QUIC output metrics.
`composer_moq_input_`	MoQ / Packager source	Per-source media-over-QUIC input metrics.
`composer_runtime_`	Runtime lifecycle	Process- and session-level metrics for the headless Composer Runtime.

Every metric additionally carries the static labels systemlabel, version, and hostname, applied at startup so a single Prometheus/Grafana instance can disambiguate many Composer hosts. Counters (cumulative since process start) are marked Counter below; everything else is a Gauge (an instantaneous value, even where the name ends in _total or _count).

Baseline metrics

Always emitted, on every licence tier. These drive the core render-health panels and the per-severity log counters.

Metric	Type	Description
`composer_frames_processed_total`	Gauge	Total processed video frames since process start.
`composer_congestions_last_second`	Gauge	Congestive frames in the last second.
`composer_congestive_frames_since_start`	Gauge	Total congestive frames since process start.
`composer_processing_queue_length`	Gauge	Current render processing queue length.
`composer_last_frame_processing_time`	Gauge	Processing time of the most recent frame in ms.
`composer_max_processing_time`	Gauge	Maximum frame processing time observed in ms.
`composer_average_processing_time`	Gauge	Average frame processing time in ms.
`composer_gpu_ram_usage`	Gauge	GPU RAM used by the process in GB.
`composer_fatal_error_count_total`	Counter	Total fatal errors logged since process start.
`composer_error_count_total`	Counter	Total errors logged since process start.
`composer_warning_count_total`	Counter	Total warnings logged since process start.

Processing

Extended render-loop timing beyond the baseline frame counters.

Metric	Type	Description
`composer_ext_average_processing_time_10k_frames`	Gauge	Average frame processing time over the last 10k frames in ms.
`composer_ext_average_processing_usage_10k_frames`	Gauge	Average processing-budget usage over the last 10k frames in percent.
`composer_ext_last_frame_processing_usage`	Gauge	Processing-budget usage of the most recent frame in percent.
`composer_ext_worker_queue_flushes`	Gauge	Worker queue flushes since process start.

GPU

Sampled from nvidia-smi. All values are for the GPU Composer is bound to.

Metric	Type	Description
`composer_ext_gpu_power_usage_percentage`	Gauge	GPU power draw as a percentage of the power limit.
`composer_ext_gpu_power_usage`	Gauge	GPU power draw in watts.
`composer_ext_gpu_power_limit`	Gauge	GPU power limit in watts.
`composer_ext_gpu_power_state`	Gauge	GPU performance state (P-state) reported by nvidia-smi, as an integer.
`composer_ext_gpu_power_management_enabled`	Gauge	1 if GPU power management is enabled, 0 otherwise.
`composer_ext_gpu_utilization`	Gauge	GPU core utilisation percentage.
`composer_ext_gpu_encoder_utilization`	Gauge	GPU hardware encoder utilisation percentage.
`composer_ext_gpu_decoder_utilization`	Gauge	GPU hardware decoder utilisation percentage.
`composer_ext_gpu_memory_total`	Gauge	Total GPU memory in GB.
`composer_ext_gpu_memory_used`	Gauge	Used GPU memory in GB.
`composer_ext_gpu_memory_available`	Gauge	Available GPU memory in GB.
`composer_ext_gpu_temperature`	Gauge	GPU temperature in degrees Celsius.

System memory

Process RAM (not host-wide memory), in GB.

Metric	Type	Description
`composer_ext_system_memory_usage`	Gauge	Process RAM usage in GB.
`composer_ext_system_memory_usage_avg_10min`	Gauge	Average process RAM usage over the last 10 minutes in GB.
`composer_ext_system_memory_usage_max_10min`	Gauge	Peak process RAM usage over the last 10 minutes in GB.
`composer_ext_system_memory_usage_min_10min`	Gauge	Minimum process RAM usage over the last 10 minutes in GB.

RTMP targets (aggregate)

Roll-ups across all RTMP targets in the project. For per-target detail, see Per-instance metrics below.

Metric	Type	Description
`composer_ext_rtmp_target_count`	Gauge	Number of RTMP target instances.
`composer_ext_rtmp_target_nvenc_count`	Gauge	Number of RTMP targets using the NVENC encoder.
`composer_ext_rtmp_target_x264_count`	Gauge	Number of RTMP targets using the x264 software encoder.
`composer_ext_rtmp_target_connected_count`	Gauge	Number of RTMP targets currently connected.
`composer_ext_rtmp_target_disconnected_count`	Gauge	Number of RTMP targets currently disconnected.
`composer_ext_rtmp_target_connecting_count`	Gauge	Number of RTMP targets currently connecting.
`composer_ext_rtmp_target_disconnecting_count`	Gauge	Number of RTMP targets currently disconnecting.
`composer_ext_rtmp_target_reconnecting_count`	Gauge	Number of RTMP targets currently reconnecting.
`composer_ext_rtmp_target_errors`	Gauge	Number of RTMP targets currently in an error state.
`composer_ext_rtmp_target_warnings`	Gauge	Number of RTMP targets currently in a warning state.
`composer_ext_rtmp_target_error_count`	Counter	Total RTMP target errors since process start.
`composer_ext_rtmp_target_warning_count`	Counter	Total RTMP target warnings since process start.
`composer_ext_rtmp_target_auto_reconnect_count`	Gauge	Total automatic RTMP target reconnections.
`composer_ext_rtmp_target_sum_outgoing_bitrate`	Gauge	Combined outgoing bitrate across all RTMP targets in Mbit/s.
`composer_ext_rtmp_target_avg_network_write_time`	Gauge	Average network write time across RTMP targets in ms.
`composer_ext_rtmp_target_avg_video_encode_time`	Gauge	Average video encode time across RTMP targets in ms.
`composer_ext_rtmp_target_all_connected`	Gauge	1 if all RTMP targets are connected, 0 otherwise.
`composer_ext_rtmp_target_max_pts_diff`	Gauge	Maximum PTS difference across RTMP targets in ms.

Per-instance metrics

One time series per input/target instance, identified by the labels instance_id and instance_name. Series are removed from the endpoint when their instance is torn down, so a stopped target stops appearing rather than reporting stale values. connection_status is encoded as 0=Disconnected, 1=Connecting, 2=Connected, 3=Reconnecting; buffer_state / buffering_state as 0=None, 1=Buffering, 2=Buffered; listener and playback states are raw integer enum values.

RTMP target (per instance_id, instance_name)

Metric	Type	Description
`composer_ext_rtmp_target_instance_connection_status`	Gauge	Connection status: 0=Disconnected, 1=Connecting, 2=Connected, 3=Reconnecting.
`composer_ext_rtmp_target_instance_outgoing_bitrate_mbps`	Gauge	Outgoing bitrate in Mbit/s.
`composer_ext_rtmp_target_instance_output_queue_size`	Gauge	Output queue depth.
`composer_ext_rtmp_target_instance_avg_video_encode_time_ms`	Gauge	Average video encode time in ms.
`composer_ext_rtmp_target_instance_max_video_encode_time_ms`	Gauge	Maximum video encode time in ms.
`composer_ext_rtmp_target_instance_avg_network_write_time_ms`	Gauge	Average network write time in ms.
`composer_ext_rtmp_target_instance_pts_diff_average`	Gauge	Average PTS difference in ms.
`composer_ext_rtmp_target_instance_auto_reconnects`	Gauge	Automatic reconnections performed.
`composer_ext_rtmp_target_instance_video_frames_written`	Gauge	Video frames written.
`composer_ext_rtmp_target_instance_error_count`	Gauge	Error count for this target.
`composer_ext_rtmp_target_instance_warning_count`	Gauge	Warning count for this target.

SRT target (per instance_id, instance_name)

Metric	Type	Description
`composer_ext_srt_target_instance_connection_status`	Gauge	Connection status: 0=Disconnected, 1=Connecting, 2=Connected, 3=Reconnecting.
`composer_ext_srt_target_instance_outgoing_bitrate_mbps`	Gauge	Outgoing bitrate in Mbit/s.
`composer_ext_srt_target_instance_output_queue_size`	Gauge	Output queue depth.
`composer_ext_srt_target_instance_avg_video_encode_time_ms`	Gauge	Average video encode time in ms.
`composer_ext_srt_target_instance_max_video_encode_time_ms`	Gauge	Maximum video encode time in ms.
`composer_ext_srt_target_instance_avg_network_write_time_ms`	Gauge	Average network write time in ms.
`composer_ext_srt_target_instance_auto_reconnects`	Gauge	Automatic reconnections performed.
`composer_ext_srt_target_instance_video_frames_written`	Gauge	Video frames written.
`composer_ext_srt_target_instance_error_count`	Gauge	Error count for this target.
`composer_ext_srt_target_instance_warning_count`	Gauge	Warning count for this target.

RTMP input (per instance_id, instance_name)

Metric	Type	Description
`composer_ext_rtmp_input_instance_connection_status`	Gauge	Connection status: 0=Disconnected, 1=Connecting, 2=Connected, 3=Reconnecting.
`composer_ext_rtmp_input_instance_video_buffer_size_frames`	Gauge	Video buffer depth in frames.
`composer_ext_rtmp_input_instance_video_buffer_size_ms`	Gauge	Video buffer depth in ms.
`composer_ext_rtmp_input_instance_audio_buffer_size_ms`	Gauge	Audio buffer depth in ms.
`composer_ext_rtmp_input_instance_buffer_state`	Gauge	Buffer state: 0=None, 1=Buffering, 2=Buffered.
`composer_ext_rtmp_input_instance_auto_reconnects`	Gauge	Automatic reconnections performed.
`composer_ext_rtmp_input_instance_flushes`	Gauge	Buffer flushes performed.

SRT input (per instance_id, instance_name)

Metric	Type	Description
`composer_ext_srt_input_instance_listener_status`	Gauge	Listener status as an integer enum value.
`composer_ext_srt_input_instance_buffering_state`	Gauge	Buffering state: 0=None, 1=Buffering, 2=Buffered.
`composer_ext_srt_input_instance_video_buffer_size_frames`	Gauge	Video buffer depth in frames.
`composer_ext_srt_input_instance_video_buffer_size_ms`	Gauge	Video buffer depth in ms.
`composer_ext_srt_input_instance_audio_buffer_size_ms`	Gauge	Audio buffer depth in ms.
`composer_ext_srt_input_instance_video_audio_sync_ms`	Gauge	Video/audio sync offset in ms.
`composer_ext_srt_input_instance_auto_reconnects`	Gauge	Automatic reconnections performed.
`composer_ext_srt_input_instance_flushes`	Gauge	Buffer flushes performed.
`composer_ext_srt_input_instance_buffer_underruns`	Gauge	Buffer under-runs.
`composer_ext_srt_input_instance_video_decode_errors`	Gauge	Video decode errors.
`composer_ext_srt_input_instance_packets_received`	Gauge	Packets received.
`composer_ext_srt_input_instance_rendered_frames`	Gauge	Rendered frames.

DeckLink input (per instance_id, instance_name)

Metric	Type	Description
`composer_ext_decklink_input_instance_playback_state`	Gauge	Playback state as an integer enum value.
`composer_ext_decklink_input_instance_captured_frames`	Gauge	Captured frames.
`composer_ext_decklink_input_instance_playback_frames`	Gauge	Playback frames.
`composer_ext_decklink_input_instance_zero_data_frames`	Gauge	Zero-data frames captured.

DeckLink output (per instance_id, instance_name)

Metric	Type	Description
`composer_ext_decklink_output_instance_playback_state`	Gauge	Playback state as an integer enum value.
`composer_ext_decklink_output_instance_frames_displayed`	Gauge	Frames displayed.

MoQ / Packager targets

Per media-over-QUIC output (MoQTarget / packager sink), labelled target_id, target_name, and sink_type. composer_packager_sink_target_count is the only unlabelled roll-up.

Metric	Type	Description
`composer_packager_sink_target_count`	Gauge	Number of MoQTarget/PackagerSink instances.
`composer_packager_sink_target_connection_status`	Gauge	Connection status: 0=Disconnected, 1=Connecting, 2=Connected, 3=Reconnecting.
`composer_packager_sink_target_reconnection_count_total`	Counter	Total reconnections for this target since process start.
`composer_packager_sink_target_frames_processed_total`	Counter	Total frames processed by this target since process start.
`composer_packager_sink_target_packets_sent_total`	Counter	Total packets sent by this target since process start.
`composer_packager_sink_target_avg_video_processing_time`	Gauge	Average video processing time in ms.
`composer_packager_sink_target_avg_encoding_time`	Gauge	Average encoding time in ms.
`composer_packager_sink_target_avg_total_time`	Gauge	Average total processing time in ms.
`composer_packager_sink_target_peak_video_processing_time`	Gauge	Peak video processing time in ms.
`composer_packager_sink_target_peak_encoding_time`	Gauge	Peak encoding time in ms.
`composer_packager_sink_target_video_input_queue_depth`	Gauge	Video input queue depth.
`composer_packager_sink_target_encoding_input_queue_depth`	Gauge	Encoding input queue depth.
`composer_packager_sink_target_output_queue_depth`	Gauge	Output queue depth.
`composer_packager_sink_target_outgoing_bitrate_mbps`	Gauge	Outgoing bitrate in Mbit/s (30-second rolling average).

MoQ / Packager sources

Per media-over-QUIC input (MoQInput / packager source), labelled id, name, and source_type. composer_moq_input_count is the only unlabelled roll-up.

Metric	Type	Description
`composer_moq_input_count`	Gauge	Number of MoQInput instances.
`composer_moq_input_connection_status`	Gauge	Connection status: 0=Disconnected, 1=Connecting, 2=Connected, 3=Reconnecting.
`composer_moq_input_reconnection_count_total`	Counter	Total reconnections for this source since process start.
`composer_moq_input_packets_received_total`	Counter	Total packets received by this source since process start.
`composer_moq_input_rendered_frames_total`	Counter	Total frames rendered by this source since process start.
`composer_moq_input_video_frames_decoded_total`	Counter	Total video frames decoded by this source since process start.
`composer_moq_input_audio_frames_decoded_total`	Counter	Total audio frames decoded by this source since process start.
`composer_moq_input_buffer_underruns_total`	Counter	Total buffer under-runs for this source since process start.
`composer_moq_input_video_decode_errors_total`	Counter	Total video decode errors for this source since process start.
`composer_moq_input_video_buffer_ms`	Gauge	Video buffer size in ms.
`composer_moq_input_audio_buffer_ms`	Gauge	Audio buffer size in ms.
`composer_moq_input_incoming_video_bitrate_mbps`	Gauge	Incoming video bitrate in Mbit/s.
`composer_moq_input_incoming_audio_bitrate_mbps`	Gauge	Incoming audio bitrate in Mbit/s.
`composer_moq_input_avg_decode_time_ms`	Gauge	Average video decode time in ms.
`composer_moq_input_peak_decode_time_ms`	Gauge	Peak video decode time in ms.
`composer_moq_input_connect_latency_ms`	Gauge	Last connect latency in ms.
`composer_moq_input_is_congested`	Gauge	1 if the source is congested, 0 otherwise.
`composer_moq_input_video_audio_sync_ms`	Gauge	Video/audio sync offset in ms.

Alarms

Metric	Type	Description
`composer_ext_alarms_total_count`	Counter	Total alarms triggered since process start.
`composer_ext_alarms_currently_active`	Gauge	Number of alarms currently active.

WebSockets

Real-time API traffic — connected clients, throughput, and queue depths.

Metric	Type	Description
`composer_ext_incoming_websocket_messages_total`	Counter	Total WebSocket messages received since process start.
`composer_ext_sent_websocket_messages_total`	Counter	Total WebSocket messages sent since process start.
`composer_ext_websockets_incoming_queue_size`	Gauge	Current inbound WebSocket queue size.
`composer_ext_websockets_outgoing_queue_size`	Gauge	Current outbound WebSocket queue size.
`composer_ext_websocket_processing_time_ms`	Gauge	WebSocket processing time in ms.
`composer_ext_websocket_incoming_message_count_total`	Gauge	Cumulative inbound WebSocket message count.
`composer_ext_websocket_outgoing_message_count_total`	Gauge	Cumulative outbound WebSocket message count.
`composer_ext_websocket_clients_connected`	Gauge	Number of currently connected WebSocket clients.
`composer_ext_websocket_egress_bytes_per_second_average`	Gauge	Average outbound WebSocket throughput in bytes per second.
`composer_ext_websocket_ingress_bytes_per_second_average`	Gauge	Average inbound WebSocket throughput in bytes per second.
`composer_ext_websocket_egress_messages_per_second`	Gauge	Outbound WebSocket messages per second.
`composer_ext_websocket_egress_bytes_per_second`	Gauge	Outbound WebSocket throughput in bytes per second.

Runtime lifecycle

Process- and session-level metrics for the headless Composer Runtime. composer_runtime_api_calls_total carries an endpoint label.

Metric	Type	Description
`composer_runtime_uptime_seconds`	Gauge	Runtime process uptime in seconds.
`composer_runtime_project_uptime_seconds`	Gauge	Current project session uptime in seconds.
`composer_runtime_project_loaded`	Gauge	1 if a project is loaded and running, 0 otherwise.
`composer_runtime_projects_started_total`	Counter	Total projects started since runtime launch.
`composer_runtime_reloads_total`	Counter	Total project reloads since runtime launch.
`composer_runtime_api_calls_total`	Counter	Total runtime API calls since runtime launch. (label: `endpoint`)
`composer_runtime_errors_total`	Gauge	Cumulative errors across all project sessions since runtime launch.
`composer_runtime_warnings_total`	Gauge	Cumulative warnings across all project sessions since runtime launch.
`composer_runtime_last_reload_duration_seconds`	Gauge	Duration of the last project reload in seconds.
`composer_runtime_last_time_to_first_frame_seconds`	Gauge	Time from the last start/reload to the first frame rendered, in seconds.
`composer_runtime_compute_time_ms_short`	Gauge	Average compute time over the last ~100 frames in ms.
`composer_runtime_compute_time_ms_long`	Gauge	Average compute time over the last ~10k frames in ms.
`composer_runtime_congestions`	Gauge	Congestive frames in the current project session.
`composer_runtime_queue_flushes`	Gauge	Worker queue flushes in the current project session.

Project and API

Metric	Type	Description
`composer_ext_project_fps`	Gauge	Configured project frame rate in frames per second.
`composer_ext_api_call_count`	Counter	Total HTTP API calls since process start.
`composer_ext_allow_grafana_alerts`	Gauge	1 if Grafana alerts are enabled for this instance, 0 otherwise.
`composer_ext_runtime_state_enum`	Gauge	Runtime lifecycle state exposed as an integer enum value.

The /metrics endpoint is self-describing: each metric carries its own # HELP and # TYPE lines. The tables above are kept in sync with the engine's metric definitions, but pointing a browser at a running instance's /metrics endpoint always shows the exact set emitted by that specific build.