Router Telemetry

In this overview, learn about:

• How GraphOS Router and Apollo Router Core telemetry enable supergraph observability and debuggability

• What data is captured in the router's logs, metrics, and traces

• What exporters are available to provide telemetry to your application performance monitoring (APM) tools

Observability through telemetry

The health of your supergraph is only as good as the health of your router. Because the router is the single entry point to the supergraph, all client requests pass through the router's request lifecycle. Any issues with the router are likely to affect the handling of all requests to your supergraph.

Diagnosing your router's health and performance requires it to show observable data about its inner workings. The more observable data you can monitor and analyze, the faster you can identify unhealthy behaviors, deduce root causes, and implement fixes.

The router provides the necessary data to monitor its health and troubleshoot issues. The router's observability is critical for maintaining a healthy, performant supergraph and minimizing its mean time to repair (MTTR).

Collect exactly the telemetry you need

Effective telemetry provides just the right amount and granularity of information to maintain your graph. Too much data can overwhelm your system, for example, with high cardinality metrics. Too little may not provide enough information to debug issues.

Specific events that need to be captured—and the conditions under which they need to be captured—can change as client applications and graphs change. Different environments, such as production and development, can have different observability requirements.

Router telemetry is customizable to meet the observability needs of different graphs. You can record custom events in different stages of the router request lifecycle and create custom contexts with attributes to track a request or response as it flows through the router. You can shape the volume and rate of emitted telemetry, for example, with batched telemetry.

Router telemetry types

The router collects different types of telemetry, including:

• Logs and events

• Metrics and instruments

• Traces and spans

These let you collect data about the inner workings of your router and export logs, metrics, and traces to your application performance monitoring (APM) and observability tools.

Logs and events

Logs record events in the router. Examples of logged events include:

• Information about the router lifecycle

• Warnings about misconfiguration

• Errors that occurred during a request

Logs can be consumed by logging exporters and as part of spans via tracing exporters.

Metrics and instruments

Metrics are measurements of the router's behavior that can be exported and monitored. Different kinds of metrics include histograms, gauges, and counts.

Metrics can be consumed by exporters. See Metrics exporters for an overview of supported exporters.

An individual metric is called an instrument. Example instruments of the router include:

• Number of received requests

• Histogram of request durations

• Number of in-flight requests

See Instruments for an overview of available instruments and a guide for configuring and customizing instruments.

Traces and spans

Traces monitor the flow of a request through the router. A trace is composed of spans. A span captures a request's duration as it flows through the router request lifecycle. Spans may include contextual information about the request, such as the HTTP status code, or the name of the subgraph being queried.

Examples of spans include:

• router - Wraps an entire request from the HTTP perspective

• supergraph - Wraps a request once GraphQL parsing has taken place

• subgraph - Wraps a request to a subgraph.

Traces are consumed via tracing exporters.

Router telemetry exporters

The router exports its collected telemetry in formats compatible with industry-standard APM tools. The router supports logging, metrics, and tracing exporters for a variety of tools, including:

• Prometheus

• OpenTelemetry Collector

• Datadog

• New Relic

• Jaeger

• Zipkin

For more information, see logging exporters, metrics exporters, and tracing exporters.

Router telemetry attributes

You can annotate events, metrics, and spans with attributes. Attributes are key-value pairs that add contextual information about the router pipeline to telemetry. You can then use these attributes to filter and group data in your APMs.

Example attributes include:

• HTTP status code

• GraphQL operation name

• Subgraph name

You can use standard attributes or selectors as span attributes.

Best practices

Balancing telemetry and router performance

Keep in mind that the amount of telemetry you add can impact your router's performance.

• Custom metrics, events, and attributes consume more processing resources than standard metrics. Adding too many (standard or custom) can slow your router down.

• Configurations such as events.*.request|error|response that produce output for all router lifecycle services should only be used for development or debugging, not for production.

For properly logged telemetry, you should use a log verbosity of info. Set the values of RUST_LOG or APOLLO_ROUTER_LOG environment variables and the --log CLI option to info. Using less verbose logging, such as error, can cause some attributes to be dropped.