Metrics

Publish aggregate throughput, latency, and error telemetry for Prometheus-oriented monitoring.

This page belongs to the immutable 0.2.0 Private Preview documentation.

At a glance

Property	Value
Pipeline phase	Request + response
Category	Observability
Canonical minimum tier	Free
Legacy dashboard tier label	Free
Legacy rendered name	Metrics
Legacy rendered summary	Prometheus-compatible metrics for MongoDB traffic: throughput, latency, errors.
Canonical entitlement	Yes
Supported deployment contract	Yes
Release status	Reconciled and executable.

Release accuracy

• 0.2.0 Private Preview: Reconciled and executable.

The detailed material below preserves every section rendered by the legacy dashboard. Where it conflicts with the release status above, the release status is authoritative. Legacy field names and examples are not a substitute for the selected bundle's CRD and runtime contract. Unsafe legacy wording is retained in metadata for traceability but is corrected in the rendered guidance.

Release-aware feature flow. The diagram is explanatory; the release status on this page is authoritative.

Diagram resources: Open the SVG full screen · Download the editable Excalidraw source

Performance impact

:::warning Legacy, unverified performance claims

These numbers are preserved for documentation parity with the legacy dashboard. They are not current benchmarks or service guarantees and have not been verified by the current test suite.

:::

Percentile	Legacy claim
P50	0.08ms
P95	0.15ms
P99	0.30ms

Legacy note: In-memory counter updates. No I/O on hot path.

Overview

The Metrics step instruments every MongoDB operation with Prometheus counters, histograms, and gauges. It exposes request rate, latency distribution, error rate, and active connections — broken down by command type, database, and collection.

Metrics are exported via the standard /metrics HTTP endpoint (port 9090) and are compatible with Prometheus, Grafana, Datadog, and any OpenMetrics scraper.

When to use

• Monitoring MongoDB traffic throughput and latency in real-time
• Setting up alerts on error rate spikes or latency degradation
• Capacity planning based on actual traffic patterns
• Building Grafana dashboards for MongoDB operational visibility

How it works

1. Request phase: Increments nexo_requests_total counter with labels (command, db, collection). Records request size in nexo_request_size_bytes histogram.
2. Response phase: Records latency in nexo_request_duration_seconds histogram. Increments nexo_errors_total if the response indicates failure.
3. Maintains nexo_active_connections gauge for concurrent connection tracking.

Configuration

The table preserves the legacy dashboard field reference. “Not specified” means the legacy source did not declare required semantics.

Field	Legacy UI type	Legacy default	Required	Description
histogram_buckets	string	1,5,10,25,50,100,250,500,1000,5000	No	Custom latency histogram buckets (comma-separated ms values)
include_collection	bool	true	No	Add collection label to metrics (high cardinality warning)
namespace	string	nexo	No	Prometheus metric prefix

Settings reference

The legacy page did not render an additional anchored settings reference.

Examples

Default metrics collection

steps:
  - name: builtin:metrics
    config:
      include_collection: true
      namespace: nexo

Best practices

• Keep include_collection: true unless you have >1000 collections (cardinality explosion)
• Use pre-built Grafana dashboards from the Nexo marketplace
• Set alerts on nexo_errors_total rate and nexo_request_duration_seconds p99

Limitations

• Collection-level labels can cause high memory usage with many collections
• Only tracks OP_MSG operations (MongoDB 3.6+ wire protocol)

Security and operational guidance

• Do not place raw query payloads in labels
• Keep customer-controlled labels bounded
• Treat metrics endpoints as operationally sensitive

Related steps

• logging
• rate-limit

Release availability

• 0.2.0 Private Preview: Reconciled and executable.

See the component catalog for the complete comparison matrix.