Tracing in the Apollo Router

Collect tracing information

The Apollo Router supports OpenTelemetry, with exporters for:

Jaeger
Zipkin
Datadog
OpenTelemetry Protocol (OTLP) over HTTP or gRPC

The Apollo Router generates spans that include the various phases of serving a request and associated dependencies. This is useful for showing how response time is affected by:

Sub-request response times
Query shape (sub-request dependencies)
Apollo Router post-processing

Span data is sent to a collector such as Jaeger, which can assemble spans into a gantt chart for analysis.

To get the most out of distributed tracing, all components in your system should be instrumented.

In your router's YAML config file, the trace_config section contains common configuration that's used by all exporters. This section is optional, and it falls back on the values of environment variables specified by the OpenTelemetry spec if service_name is not set.

router.yaml

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telemetry:
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  tracing:
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    trace_config:
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      service_name: "router"
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      service_namespace: "apollo"
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      # Optional. Either a float between 0 and 1 or 'always_on' or 'always_off'
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      sampler: 0.1
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      # Optional. Use a parent based sampler. This enables remote spans help make a decision on if a span is sampeld or not.
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      # https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#parentbased
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      parent_based_sampler: false
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      # Optional limits
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      max_attributes_per_event: 10
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      max_attributes_per_link: 10
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      max_attributes_per_span: 10
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      max_events_per_span: 10
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      max_links_per_span: 10
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      # Attributes particular to an exporter that have not
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      # been explicitly handled in Router configuration.
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      attributes:
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        some.config.attribute: "config value"

If service_name is set, then environment variables are not used. However, you can embed environment variables into your router config using Unix ${key:default} syntax.

If no environment variable is set and service_name is not present then router is used as the default service name.

Propagation

The propagation section allows you to configure which propagators are active in addition to those automatically activated by using an exporter.

router.yaml

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telemetry:
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  tracing:
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    propagation:
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      # https://www.w3.org/TR/baggage/
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      baggage: false
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      # https://www.datadoghq.com/
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      datadog: false
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      # https://www.jaegertracing.io/ (compliant with opentracing)
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      jaeger: false
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      # https://www.w3.org/TR/trace-context/
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      trace_context: false
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      # https://zipkin.io/ (compliant with opentracing)
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      zipkin: false

Specifying explicit propagation is generally only required if you're using an exporter that supports multiple trace ID formats (e.g., OpenTelemetry Collector, Jaeger, or OpenTracing compatible exporters).

Using Datadog

The Apollo Router can be configured to connect to either the default agent address or a URL.

router.yaml

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telemetry:
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  tracing:
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    datadog:
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      # Either 'default' or a URL
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      endpoint: default

Using Jaeger

The Apollo Router can be configured to export tracing data to Jaeger either via an agent or http collector.

Agent config

router.yaml

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telemetry:
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  tracing:
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    jaeger:
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      agent:
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        # Either 'default' or a URL
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        endpoint: docker_jaeger:14268

Collector config

If you're using Kubernetes, you can inject your secrets into configuration via environment variables:

router.yaml

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telemetry:
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  tracing:
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    jaeger:
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      collector:
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        endpoint: "http://my-jaeger-collector"
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        username: "${env.JAEGER_USERNAME}"
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        password: "${env.JAEGER_PASSWORD}"

OpenTelemetry Collector via OTLP

OpenTelemetry Collector is a horizontally scalable collector that you can use to receive, process, and export your telemetry data in a pluggable way.

If you find that the built-in telemetry features of the Apollo Router are missing some desired functionality (e.g., exporting to Kafka), then it's worth considering this option.

router.yaml

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telemetry:
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  tracing:
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    otlp:
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      # Either 'default' or a URL
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      endpoint: default
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      # Optional protocol (Defaults to grpc)
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      protocol: grpc
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      # Optional Grpc configuration
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      grpc:
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        domain_name: "my.domain"
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        key: ""
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        ca: ""
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        cert: ""
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        metadata:
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          foo: bar
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      # Optional Http configuration
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      http:
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        headers:
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          foo: bar
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      # Optional timeout in humantime form
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      timeout: 2s

Remember that file. and env. prefixes can be used for expansion in config yaml. e.g. ${file.ca.txt}.

Using Zipkin

The Apollo Router can be configured to export tracing data to either the default collector address or a URL:

router.yaml

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telemetry:
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  tracing:
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    zipkin:
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      # Either 'default' or a URL
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      endpoint: http://my_zipkin_collector.dev

Edit on GitHub

Collecting metrics

Overview

Tracing in the Apollo Router

Collect tracing information

Common configuration

Trace config

Propagation

Using Datadog

Using Jaeger

Agent config

Collector config

OpenTelemetry Collector via OTLP

Using Zipkin