Instrumentation Libraries

When you develop an app, you might use third-party libraries and frameworks to accelerate your work. If you then instrument your app using OpenTelemetry, you might want to avoid spending additional time to manually add traces, logs, and metrics to the third-party libraries and frameworks you use.

Many libraries and frameworks already support OpenTelemetry or are supported through OpenTelemetry instrumentation, so that they can generate telemetry you can export to an observability back end.

If you are instrumenting an app or service that use third-party libraries or frameworks, follow these instructions to learn how to use natively instrumented libraries and instrumentation libraries for your dependencies.

Use natively instrumented libraries

If a library comes with OpenTelemetry support by default, you can get traces, metrics, and logs emitted from that library by adding and setting up the OpenTelemetry SDK with your app.

The library might require some additional configuration for the instrumentation. Go to the documentation for that library to learn more.

Use instrumentation libraries

OpenTelemetry-Swift provides several instrumentation libraries that generate instrumentation for you when they’re installed and initialized.

For example, the NSURLSession instrumentation automatically creates spans for all network requests made with NSURLSessions.

Setup

All instrumentation libraries are available in OpenTelemetry Swift. To turn on an instrumentation, follow its usage instructions.

SDKResourceExtension

SDKResourceExtension provides details about the device as a Resource.

Usage

Use DefaultResource.get() to generate an all-in-one resource object. This resource can be added to a TracerProvider or MetricProvider.

OpenTelemetry.registerTracerProvider(traceProvider: TracerProviderBuilder()
            .with(resource: DefaultResource.get())
            .build())

Details

SDKResourceExtension provides attributes in a resource object with details about the iOS device, OS details, and application details. It applies these values to the appropriate semantic attributes.

Application Info

Device Info

Operating System Info

NSURLSession instrumentation

This instrumentation creates spans for all network requests made with NSURLSessions. It also injects distributed tracing headers in instrumented network requests. NetworkStatus is a dependency of this package, which provides network status attributes on network spans.

Note: The NSURLSession instrumentation relies on the global tracer provider in the OpenTelemetry object. Custom tracer providers must be configured and set as the global provider prior to this instrumentation.

Usage

Initialize the class with URLSessionInstrumentation(configuration: URLSessionInstrumentationConfiguration()) to automatically capture all network calls.

This behavior can be modified or augmented by using the optional callbacks defined in URLSessionInstrumentationConfiguration:

• shouldInstrument: ((URLRequest) -> (Bool)?)?

  Filter which requests you want to instrument, all by default.

• shouldRecordPayload: ((URLSession) -> (Bool)?)?

  Implement if you want the session to record payload data, false by default.

• shouldInjectTracingHeaders: ((URLRequest) -> (Bool)?)?

  Allow filtering which requests you want to inject headers to follow the trace, true by default. You must also return true if you want to inject custom headers.

• injectCustomHeaders: ((inout URLRequest, Span?) -> Void)?

  Implement this callback to inject custom headers or modify the request in any other way.

• nameSpan: ((URLRequest) -> (String)?)?

  Modify the name for the given request instead of standard OpenTelemetry name.

• createdRequest: ((URLRequest, Span) -> Void)?

  Called after request is created, it allows to add extra information to the Span.

• receivedResponse: ((URLResponse, DataOrFile?, Span) -> Void)?

  Called after response is received, it allows to add extra information to the Span.

• receivedError: ((Error, DataOrFile?, HTTPStatus, Span) -> Void)?

  Called after an error is received, it allows to add extra information to the Span.

Below is an example of initialization. URLSessionInstrumentationConfiguration’s construction can be passed the parameters defined above to suit the needs of the application.

let sessionInstrumentation = URLSessionInstrumentation(configuration: URLSessionInstrumentationConfiguration())

Details

NSURLSession instrumentation also provides additional attributes providing details about the network state of the device at the time of network requests.

SignpostIntegration

This package creates os_signpost begin and end calls when spans are started or ended. It allows automatic integration of applications instrumented with OpenTelemetry to show their spans in a profiling app like Instruments. It also exports the OSLog it uses for posting so the user can add extra signpost events. This functionality is shown in Simple Exporter example.

Usage

Add SignpostIntegration as any other Span Processor (see the manual instrumentation) docs for details on configuring your providers:

OpenTelemetry.instance.tracerProvider.addSpanProcessor(SignPostIntegration())

Available instrumentation libraries

A full list of instrumentation libraries produced by OpenTelemetry is available from the opentelemetry-swift repository.

You can also find more instrumentations available in the registry.

Next steps

After you have set up instrumentation libraries, you might want to add your own instrumentation to your code, to collect custom telemetry data.