The Hydrolix stack includes Prometheus, an open-source metrics database. While the Stack runs, Hydrolix continuously updates its Prometheus instance with metrics information. You can query, view, and actively monitor this information through the use of a stack's Grafana instance or you can access it via your own monitoring platform.

Using Prometheus directly

Prometheus has its own web-based UI, available by visiting https://YOUR-HYDROLIX-HOSTNAME.hydrolix.live/prometheus in your web browser.

This view is far more basic than Grafana's, suitable for quickly entering queries and seeing simple, graphed results. Hydrolix does make this feature available immediately, without any additional setup.

Hydrolix's metrics

This table lists the metrics available for merge.

For more information about metric types, refer to Prometheus's documentation.

Merge metrics

These metrics correspond to Hydrolix's merge service.

Metric	Type	Components	Purpose
`merge_duration_summary`	Summary	Merge peer	Merge processing duration, in milliseconds.
`merge_duration_histo`	Histogram	Merge peer	Merge processing duration, in milliseconds.
`merge_sdk_duration_summary`	Summary	Merge peer	Merge SDK processing duration, in milliseconds.
`merge_sdk_duration_histo`	Histogram	Merge peer	Merge SDK processing duration, in milliseconds.
`merge_candidate_histo`	Histogram	Merge peer	Partitions per merge candidate.
`merge_success`	Counter	Merge peer	Count of merge successes.
`merge_failure`	Counter	Merge peer	Count of merge successes.

General metrics

These metrics track various counters and statistics regarding data ingestion.

Metric	Type	Components	Purpose
`bytes_written`	Counter	Batch peer, Stream peer	Bytes written to the indexer.
`partitions_created`	Counter	Batch peer, Stream peer	Count of partitions created.
`process_cpu_seconds_total`	Counter	Batch peer, Stream head, Stream peer	Total user and system CPU time spent in seconds.
`process_max_fds`	Gauge	Batch peer, Stream head, Stream peer	Maximum number of open file descriptors.
`process_open_fds`	Gauge	Batch peer, Stream head, Stream peer	Number of open file descriptors.
`process_resident_memory_bytes`	Gauge	Batch peer, Stream head, Stream peer	Resident memory size in bytes.
`process_start_time_seconds`	Gauge	Batch peer, Stream head, Stream peer	Start time of the process since unix epoch in seconds.
`process_virtual_memory_bytes`	Gauge	Batch peer, Stream head, Stream peer	Virtual memory size in bytes.
`process_virtual_memory_max_bytes`	Gauge	Batch peer, Stream head, Stream peer	Maximum amount of virtual memory available in bytes.
`promhttp_metric_handler_requests_in_flight`	Gauge	Batch peer, Stream head, Stream peer	Current number of scrapes being served.
`promhttp_metric_handler_requests_total`	Counter	Batch peer, Stream head, Stream peer	Total number of scrapes by HTTP status code.