---
title: Monitoring
kind: operations
weight: 30
restrictedtoc: true
---

## OpenTelemetry

When run as a server and configured accordingly, OPA will emit spans to an
[OpenTelemetry](https://opentelemetry.io/) collector via gRPC.

Each [REST API](../rest-api/) request sent to the server will start a span.
If processing the request involves policy evaluation, and that in turn uses
[`http.send`](../policy-reference/#http), those HTTP clients will emit descendant spans.

Furthermore, spans exported for policy evaluation requests will contain an
attribute `opa.decision_id` of the evaluation's decision ID _if_ the server
has decision logging enabled.

See [the configuration documentation](../configuration/#distributed-tracing)
for all OpenTelemetry-related configurables.

## Prometheus

OPA exposes an HTTP endpoint that can be used to collect performance metrics
for all API calls. The Prometheus endpoint is enabled by default when you run
OPA as a server.

You can enable metric collection from OPA with the following `prometheus.yml` config:

```yaml
global:
  scrape_interval: 15s
scrape_configs:
  - job_name: "opa"
    metrics_path: "/metrics"
    static_configs:
    - targets:
      - "localhost:8181"
```

The Prometheus endpoint exports Go runtime metrics as well as HTTP request latency metrics for all handlers (e.g., `v1/data`).

| Metric name | Metric type | Description | Status |
| --- | --- | --- | --- |
| go_gc_duration_seconds | summary | A summary of the GC invocation durations. | STABLE |
| go_goroutines | gauge | Number of goroutines that currently exist. | STABLE |
| go_info | gauge | Information about the Go environment. | STABLE |
| go_memstats_alloc_bytes | gauge | Number of bytes allocated and still in use. | STABLE |
| go_memstats_alloc_bytes_total | counter | Total number of bytes allocated, even if freed. | STABLE |
| go_memstats_buck_hash_sys_bytes | gauge | Number of bytes used by the profiling bucket hash table. | STABLE |
| go_memstats_frees_total | counter | Total number of frees. | STABLE |
| go_memstats_gc_sys_bytes | gauge | Number of bytes used for garbage collection system metadata. | STABLE |
| go_memstats_heap_alloc_bytes | gauge | Number of heap bytes allocated and still in use. | STABLE |
| go_memstats_heap_idle_bytes | gauge | Number of heap bytes waiting to be used. | STABLE |
| go_memstats_heap_inuse_bytes | gauge | Number of heap bytes that are in use. | STABLE |
| go_memstats_heap_objects | gauge | Number of allocated objects. | STABLE |
| go_memstats_heap_released_bytes | gauge | Number of heap bytes released to OS. | STABLE |
| go_memstats_heap_sys_bytes | gauge | Number of heap bytes obtained from system. | STABLE |
| go_memstats_last_gc_time_seconds | gauge | Number of seconds since 1970 of last garbage collection. | STABLE |
| go_memstats_lookups_total | counter | Total number of pointer lookups. | STABLE |
| go_memstats_mallocs_total | counter | Total number of mallocs. | STABLE |
| go_memstats_mcache_inuse_bytes | gauge | Number of bytes in use by mcache structures. | STABLE |
| go_memstats_mcache_sys_bytes | gauge | Number of bytes used for mcache structures obtained from system. | STABLE |
| go_memstats_mspan_inuse_bytes | gauge | Number of bytes in use by mspan structures. | STABLE |
| go_memstats_mspan_sys_bytes | gauge | Number of bytes used for mspan structures obtained from system. | STABLE |
| go_memstats_next_gc_bytes | gauge | Number of heap bytes when next garbage collection will take place. | STABLE |
| go_memstats_other_sys_bytes | gauge | Number of bytes used for other system allocations. | STABLE |
| go_memstats_stack_inuse_bytes | gauge | Number of bytes in use by the stack allocator. | STABLE |
| go_memstats_stack_sys_bytes | gauge | Number of bytes obtained from system for stack allocator. | STABLE |
| go_memstats_sys_bytes | gauge | Number of bytes obtained from system. | STABLE |
| go_threads | gauge | Number of OS threads created. | STABLE |
| http_request_duration_seconds | histogram | A histogram of duration for requests. | STABLE |


### Status Metrics

When Prometheus is enabled in the status plugin (see [Configuration](../configuration/#status)), the OPA instance's Prometheus endpoint also exposes these metrics:

| Metric name | Metric type | Description                                              | Status |
| --- | --- |----------------------------------------------------------|--------|
| opa_info | gauge | Information about the OPA environment.                    | STABLE |
| plugin_status_gauge | gauge | Number of plugins by name and status.                    | STABLE |
| bundle_loaded_counter | counter | Number of bundles loaded with success.                   | STABLE |
| bundle_failed_load_counter | counter | Number of bundles that failed to load.                   | STABLE |
| last_bundle_request | gauge | Last bundle request in UNIX nanoseconds.                 | STABLE |
| last_success_bundle_activation | gauge | Last successful bundle activation in UNIX nanoseconds. | STABLE |
| last_success_bundle_download | gauge | Last successful bundle download in UNIX nanoseconds.   | STABLE |
| last_success_bundle_request | gauge | Last successful bundle request in UNIX nanoseconds.    | STABLE |
| bundle_loading_duration_ns | histogram | A histogram of duration for bundle loading.              | STABLE |


## Health Checks

OPA exposes a `/health` API endpoint that can be used to perform health checks.
See [Health API](../rest-api#health-api) for details.

## Status API

OPA provides a plugin which can push status to a remote service.
See [Status API](../management-status) for details.
