Viewing system metrics

Your Hydrolix stack includes Prometheus, an open-source metrics database. While your stack runs, Hydrolix continuously updates its Prometheus instance with metrics information. You can query, view, and actively monitor this information through the use of your stack’s Grafana instance, after performing a one-time setup.

Using Grafana

To view your Hydrolix metrics with Grafana, you must connect your stack’s Prometheus instance as a data source into its Grafana instance.

Preparing the data source

  1. Visit your stack’s Grafana instance at https://YOUR-HYDROLIX-HOSTNAME.hydrolix.live/grafana.

  2. Select ⚙️ Configuration from the left menu bar, and then select Data Sources.

  3. Click the Add data source button.

  4. Select Prometheus from the list of compatible data sources.

  5. Enter https://YOUR-HYDROLIX-HOSTNAME.hydrolix.live/prometheus as the data source’s URL.

Entering your Prometheus instance's URL.

Finally, click Save & Test. The message “Data source is working” should appear immediately, completing this setup.

If you do not see that success message, confirm that your provided URL is correct, and that your stack has at least one prometheus service running. If you still have trouble getting Grafana to connect to Prometheus, please contact Hydrolix support.

Querying Grafana

After setting up Prometheus as a data source, you can query, graph, and monitor your Hydrolix metrics through all the tools and techniques Grafana makes available.

For a simple example, select 🧭 Explore from Grafana’s left menu bar, and then enter a basic metric-query such as process_open_fds into the text entry field. This results in a multi-line graph showing the open file descriptors in use by several of your stack’s components.

To turn this static graph into a dynamic monitor, select 5s from the pull-down menu next to the Run query button. The graph then refreshes itself every five seconds.

Viewing a simple metric query.

For a complete list of the metrics that Hydrolix makes available, see Hydrolix’s Metrics.

For more information on using Grafana and Prometheus together, you may consult Prometheus’s documentation on that topic.

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, and which components update them.

If more than one component uses a given metric, then querying it will return results from all relevant components. You can restrict results to a specific component by adding a service keyword to your query, e.g. “process_open_fds{service="stream-peer"}”.

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

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.

Batch metrics

These metrics track activity specific to batch ingestions.

Metric Type Components Purpose
processed_count Counter Batch peer Count of items processed.
processed_failure Counter Batch peer Count of processing failures.
processing_duration_histo Histogram Batch peer Histogram of Batch processing durations in milliseconds.
processing_duration_summary Summary Batch peer Summary of Batch processing durations in milliseconds.
rows_read Counter Batch peer Count of rows read.

Streaming metrics

HTTP Stream Ingest

These metrics are specific to the use of streaming data sources.

Metric Type Components Purpose
http_source_byte_count Counter Stream head Count of bytes processed.
http_source_request_count Counter Stream head Count of http requests.
http_source_request_duration_ns Histogram Stream head A histogram of HTTP request durations in nanoseconds.
http_source_request_error_count Counter Stream head Count of http request failures.
http_source_row_count Counter Stream head Count of rows processed.
http_source_value_count Counter Stream head Count of values processed.
kinesis_source_byte_count Counter Stream peer Count of bytes read from Kinesis.
kinesis_source_checkpoint_count Counter Stream peer Count of Kinesis checkpoint operations.
kinesis_source_checkpoint_duration_ns Histogram Stream peer Duration of Kinesis checkpoint operations.
kinesis_source_checkpoint_error_count Counter Stream peer Count of errors in Kinesis checkpoint operations.
kinesis_source_error_count Counter Stream peer Count of errors in Kinesis source reads.
kinesis_source_lag_ms Gauge Stream peer Measure of lag in Kinesis source.
kinesis_source_operation_count Counter Stream peer Count of operations on Kinesis.
kinesis_source_operation_duration_ns Histogram Stream peer Histogram of duration of operations on Kinesis.
kinesis_source_record_count Counter Stream peer Count of records read from Kinesis.
kinesis_source_row_count Counter Stream peer Count of rows read from Kinesis.
kinesis_source_value_count Counter Stream peer Count of values read from Kinesis.

Kafka Ingest

These metrics are specific to the use of Kafka data sources.

Metric Type Components Purpose
kafka_source_byte_count Counter Stream peer Count of bytes read from Kafka.
kafka_source_commit_duration_ns Histogram Stream peer Kafka commit duration.
kafka_source_read_count Counter Stream peer Count of Kafka reads.
kafka_source_read_duration_ns Histogram Stream peer Kafka read duration.
kafka_source_read_error_count Counter Stream peer Count of Kafka errors.
kafka_source_row_count Counter Stream peer Count of rows processed.
kafka_source_value_count Counter Stream peer Count of values processed.

Go environment metrics

These metrics track resources used by Hydrolix’s Go environments.

Metric Type Components Purpose
go_gc_duration_seconds Summary Batch peer, Stream head, Stream peer A summary of the pause duration of garbage collection cycles.
go_goroutines Gauge Batch peer, Stream head, Stream peer Number of goroutines that currently exist.
go_info Gauge Batch peer, Stream head, Stream peer Information about the Go environment.
go_memstats_alloc_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes allocated and still in use.
go_memstats_alloc_bytes_total Counter Batch peer, Stream head, Stream peer Total number of bytes allocated, even if freed.
go_memstats_buck_hash_sys_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes used by the profiling bucket hash table.
go_memstats_frees_total Counter Batch peer, Stream head, Stream peer Total number of frees.
go_memstats_gc_cpu_fraction Gauge Batch peer, Stream head, Stream peer The fraction of this program’s available CPU time used by the GC since the program started.
go_memstats_gc_sys_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes used for garbage collection system metadata.
go_memstats_heap_alloc_bytes Gauge Batch peer, Stream head, Stream peer Number of heap bytes allocated and still in use.
go_memstats_heap_idle_bytes Gauge Batch peer, Stream head, Stream peer Number of heap bytes waiting to be used.
go_memstats_heap_inuse_bytes Gauge Batch peer, Stream head, Stream peer Number of heap bytes that are in use.
go_memstats_heap_objects Gauge Batch peer, Stream head, Stream peer Number of allocated objects.
go_memstats_heap_released_bytes Gauge Batch peer, Stream head, Stream peer Number of heap bytes released to OS.
go_memstats_heap_sys_bytes Gauge Batch peer, Stream head, Stream peer Number of heap bytes obtained from system.
go_memstats_last_gc_time_seconds Gauge Batch peer, Stream head, Stream peer Number of seconds since 1970 of last garbage collection.
go_memstats_lookups_total Counter Batch peer, Stream head, Stream peer Total number of pointer lookups.
go_memstats_mallocs_total Counter Batch peer, Stream head, Stream peer Total number of mallocs.
go_memstats_mcache_inuse_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes in use by mcache structures.
go_memstats_mcache_sys_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes used for mcache structures obtained from system.
go_memstats_mspan_inuse_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes in use by mspan structures.
go_memstats_mspan_sys_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes used for mspan structures obtained from system.
go_memstats_next_gc_bytes Gauge Batch peer, Stream head, Stream peer Number of heap bytes when next garbage collection will take place.
go_memstats_other_sys_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes used for other system allocations.
go_memstats_stack_inuse_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes in use by the stack allocator.
go_memstats_stack_sys_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes obtained from system for stack allocator.
go_memstats_sys_bytes Gauge Batch peer, Stream head, Stream peer Number of bytes obtained from system.
go_threads Gauge Batch peer, Stream head, Stream peer Number of OS threads created.