@opentelemetry/sdk-trace-base
v1.27.0
Published
OpenTelemetry Tracing
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OpenTelemetry Tracing SDK
The tracing
module contains the foundation for all tracing SDKs of opentelemetry-js.
Used standalone, this module provides methods for manual instrumentation of code, offering full control over span creation for client-side JavaScript (browser) and Node.js.
It does not provide automated instrumentation of known libraries, context propagation for asynchronous invocations or distributed-context out-of-the-box.
For automated instrumentation for Node.js, please see @opentelemetry/sdk-trace-node.
Installation
npm install --save @opentelemetry/api
npm install --save @opentelemetry/sdk-trace-base
Usage
const opentelemetry = require('@opentelemetry/api');
const { BasicTracerProvider } = require('@opentelemetry/sdk-trace-base');
// To start a trace, you first need to initialize the Tracer provider.
// NOTE: The default OpenTelemetry tracer provider does not record any tracing information.
// Registering a working tracer provider allows the API methods to record traces.
new BasicTracerProvider().register();
// To create a span in a trace, we used the global singleton tracer to start a new span.
const span = opentelemetry.trace.getTracer('default').startSpan('foo');
// Set a span attribute
span.setAttribute('key', 'value');
// We must end the spans so they become available for exporting.
span.end();
Config
Tracing configuration is a merge of user supplied configuration with both the default
configuration as specified in config.ts and an
environmentally configurable sampling (via OTEL_TRACES_SAMPLER
and OTEL_TRACES_SAMPLER_ARG
).
Built-in Samplers
Sampler is used to make decisions on Span
sampling.
AlwaysOn Sampler
Samples every trace regardless of upstream sampling decisions.
This is used as a default Sampler
const {
AlwaysOnSampler,
BasicTracerProvider,
} = require("@opentelemetry/sdk-trace-base");
const tracerProvider = new BasicTracerProvider({
sampler: new AlwaysOnSampler()
});
AlwaysOff Sampler
Doesn't sample any trace, regardless of upstream sampling decisions.
const {
AlwaysOffSampler,
BasicTracerProvider,
} = require("@opentelemetry/sdk-trace-base");
const tracerProvider = new BasicTracerProvider({
sampler: new AlwaysOffSampler()
});
TraceIdRatioBased Sampler
Samples some percentage of traces, calculated deterministically using the trace ID. Any trace that would be sampled at a given percentage will also be sampled at any higher percentage.
The TraceIDRatioSampler
may be used with the ParentBasedSampler
to respect the sampled flag of an incoming trace.
const {
BasicTracerProvider,
TraceIdRatioBasedSampler,
} = require("@opentelemetry/sdk-trace-base");
const tracerProvider = new BasicTracerProvider({
// See details of ParentBasedSampler below
sampler: new ParentBasedSampler({
// Trace ID Ratio Sampler accepts a positional argument
// which represents the percentage of traces which should
// be sampled.
root: new TraceIdRatioBasedSampler(0.5)
});
});
ParentBased Sampler
- This is a composite sampler.
ParentBased
helps distinguished between the following cases:- No parent (root span).
- Remote parent with
sampled
flagtrue
- Remote parent with
sampled
flagfalse
- Local parent with
sampled
flagtrue
- Local parent with
sampled
flagfalse
Required parameters:
root(Sampler)
- Sampler called for spans with no parent (root spans)
Optional parameters:
remoteParentSampled(Sampler)
(default:AlwaysOn
)remoteParentNotSampled(Sampler)
(default:AlwaysOff
)localParentSampled(Sampler)
(default:AlwaysOn
)localParentNotSampled(Sampler)
(default:AlwaysOff
)
|Parent| parent.isRemote() | parent.isSampled()| Invoke sampler|
|--|--|--|--|
|absent| n/a | n/a |root()
|
|present|true|true|remoteParentSampled()
|
|present|true|false|remoteParentNotSampled()
|
|present|false|true|localParentSampled()
|
|present|false|false|localParentNotSampled()
|
const {
AlwaysOffSampler,
BasicTracerProvider,
ParentBasedSampler,
TraceIdRatioBasedSampler,
} = require("@opentelemetry/sdk-trace-base");
const tracerProvider = new BasicTracerProvider({
sampler: new ParentBasedSampler({
// By default, the ParentBasedSampler will respect the parent span's sampling
// decision. This is configurable by providing a different sampler to use
// based on the situation. See configuration details above.
//
// This will delegate the sampling decision of all root traces (no parent)
// to the TraceIdRatioBasedSampler.
// See details of TraceIdRatioBasedSampler above.
root: new TraceIdRatioBasedSampler(0.5)
})
});
Example
See examples/basic-tracer-node for an end-to-end example, including exporting created spans.
Useful links
- For more information on OpenTelemetry, visit: https://opentelemetry.io/
- For more about OpenTelemetry JavaScript: https://github.com/open-telemetry/opentelemetry-js
- For help or feedback on this project, join us in GitHub Discussions
License
Apache 2.0 - See LICENSE for more information.