Lightdash can expose Prometheus metrics to help you monitor the performance and health of your Lightdash instance. This guide explains how to enable and configure Prometheus metrics for your self-hosted Lightdash deployment.

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Enabling Prometheus metrics

By default, Prometheus metrics are disabled in Lightdash. To enable them, set the following environment variable: 
LIGHTDASH_PROMETHEUS_ENABLED=true

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Configuration options

You can customize the Prometheus metrics endpoint using the following environment variables:
VariableDescriptionRequired?Default
LIGHTDASH_PROMETHEUS_ENABLEDEnables/Disables Prometheus metrics endpointfalse
LIGHTDASH_PROMETHEUS_PORTPort for Prometheus metrics endpoint9090
LIGHTDASH_PROMETHEUS_PATHPath for Prometheus metrics endpoint/metrics
LIGHTDASH_PROMETHEUS_PREFIXPrefix for metric names
LIGHTDASH_GC_DURATION_BUCKETSBuckets for duration histogram in seconds0.001, 0.01, 0.1, 1, 2, 5
LIGHTDASH_EVENT_LOOP_MONITORING_PRECISIONPrecision for event loop monitoring in milliseconds. Must be greater than zero.10
LIGHTDASH_PROMETHEUS_LABELSLabels to add to all metrics. Must be valid JSON

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Available metrics

Lightdash exposes the following metrics:

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Process metrics

These metrics provide information about the Node.js process running Lightdash:
MetricTypeDescription
process_cpu_user_seconds_totalcounterTotal user CPU time spent in seconds
process_cpu_system_seconds_totalcounterTotal system CPU time spent in seconds
process_cpu_seconds_totalcounterTotal user and system CPU time spent in seconds
process_start_time_secondsgaugeStart time of the process since unix epoch in seconds
process_resident_memory_bytesgaugeResident memory size in bytes
process_virtual_memory_bytesgaugeVirtual memory size in bytes
process_heap_bytesgaugeProcess heap size in bytes
process_open_fdsgaugeNumber of open file descriptors
process_max_fdsgaugeMaximum number of open file descriptors

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Node.js metrics

These metrics provide information about the Node.js runtime:
MetricTypeDescription
nodejs_eventloop_lag_secondsgaugeLag of event loop in seconds
nodejs_eventloop_lag_min_secondsgaugeThe minimum recorded event loop delay
nodejs_eventloop_lag_max_secondsgaugeThe maximum recorded event loop delay
nodejs_eventloop_lag_mean_secondsgaugeThe mean of the recorded event loop delays
nodejs_eventloop_lag_stddev_secondsgaugeThe standard deviation of the recorded event loop delays
nodejs_eventloop_lag_p50_secondsgaugeThe 50th percentile of the recorded event loop delays
nodejs_eventloop_lag_p90_secondsgaugeThe 90th percentile of the recorded event loop delays
nodejs_eventloop_lag_p99_secondsgaugeThe 99th percentile of the recorded event loop delays
nodejs_active_resourcesgaugeNumber of active resources that are currently keeping the event loop alive, grouped by async resource type
nodejs_active_resources_totalgaugeTotal number of active resources
nodejs_active_handlesgaugeNumber of active libuv handles grouped by handle type
nodejs_active_handles_totalgaugeTotal number of active handles
nodejs_active_requestsgaugeNumber of active libuv requests grouped by request type
nodejs_active_requests_totalgaugeTotal number of active requests
nodejs_heap_size_total_bytesgaugeProcess heap size from Node.js in bytes
nodejs_heap_size_used_bytesgaugeProcess heap size used from Node.js in bytes
nodejs_external_memory_bytesgaugeNode.js external memory size in bytes
nodejs_heap_space_size_total_bytesgaugeProcess heap space size total from Node.js in bytes
nodejs_heap_space_size_used_bytesgaugeProcess heap space size used from Node.js in bytes
nodejs_heap_space_size_available_bytesgaugeProcess heap space size available from Node.js in bytes
nodejs_version_infogaugeNode.js version info
nodejs_gc_duration_secondshistogramGarbage collection duration by kind
nodejs_eventloop_utilizationgaugeThe calculated Event Loop Utilization (ELU) as a percentage

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PostgreSQL metrics

These metrics provide information about the PostgreSQL connection pool:
MetricTypeDescription
pg_pool_max_sizegaugeMax size of the PG pool
pg_pool_sizegaugeCurrent size of the PG pool
pg_active_connectionsgaugeNumber of active connections in the PG pool
pg_idle_connectionsgaugeNumber of idle connections in the PG pool
pg_queued_queriesgaugeNumber of queries waiting in the PG pool queue
pg_connection_acquire_timehistogramTime to acquire a connection from the PG pool in milliseconds
pg_query_durationhistogramHistogram of PG query execution time in milliseconds

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Queue metrics

MetricTypeDescription
queue_sizegaugeNumber of jobs in the queue

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Using metrics for monitoring and alerting

You can use these metrics to create dashboards and alerts in your monitoring system. Some common use cases include:
  • Monitoring memory usage and setting alerts for potential memory leaks
  • Tracking PostgreSQL connection pool utilization
  • Monitoring event loop lag to detect performance issues
  • Setting up alerts for high CPU usage
For example, you might want to create alerts for:
  • High memory usage: process_resident_memory_bytes > threshold
  • Event loop lag: nodejs_eventloop_lag_p99_seconds > threshold
  • Database connection pool saturation: pg_active_connections / pg_pool_max_size > 0.8

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Setting up a Prometheus server

If you don’t already have a Prometheus server set up, here are some resources to help you get started:

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General Prometheus setup

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Setting up Prometheus in Google Cloud Platform (GCP)

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Setting up Prometheus in Amazon Web Services (AWS)