* docs(website_docs): fix toc * docs(website_docs): fix toc * update exporting_data.md for rerun check-links * update exporting_data.md for rerun check-links Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com> Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>
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Processing and Exporting Data | 4 | Exporting data |
Once you've instrumented your code, you need to get the data out in order to do anything useful with it. This page will cover the basics of the process and export pipeline.
Sampling
Sampling is a process that restricts the amount of traces that are generated by a system. The exact sampler you should use depends on your specific needs, but in general you should make a decision at the start of a trace, and allow the sampling decision to propagate to other services.
A sampler needs to be set on the tracer provider when its configured, as follows:
provider := sdktrace.NewTracerProvider(
sdktrace.WithSampler(sdktrace.AlwaysSample()),
)
AlwaysSample
and NeverSample
are fairly self-explanatory. Always means that every trace will be sampled, the converse holds as true for Never. When you're getting started, or in a development environment, you'll almost always want to use AlwaysSample
.
Other samplers include:
TraceIDRatioBased
, which will sample a fraction of traces, based on the fraction given to the sampler. Thus, if you set this to .5, half of traces will be sampled.ParentBased
, which behaves differently based on the incoming sampling decision. In general, this will sample spans that have parents that were sampled, and will not sample spans whose parents were not sampled.
When you're in production, you should consider using the TraceIDRatioBased
sampler with the ParentBased
sampler.
Resources
Resources are a special type of attribute that apply to all spans generated by a process. These should be used to represent underlying metadata about a process that's non-ephemeral - for example, the hostname of a process, or its instance ID.
Resources should be assigned to a tracer provider at its initialization, and are created much like attributes:
resources := resource.NewWithAttributes(
semconv.SchemaURL,
semconv.ServiceNameKey.String("myService"),
semconv.ServiceVersionKey.String("1.0.0"),
semconv.ServiceInstanceIDKey.String("abcdef12345"),
)
provider := sdktrace.NewTracerProvider(
...
sdktrace.WithResource(resources),
)
Note the use of the semconv
package to provide conventional names for resource attributes. This helps ensure that consumers of telemetry produced with these semantic conventions can
easily discover relevant attributes and understand their meaning.
Resources can also be detected automatically through resource.Detector
implementations. These Detector
s may discover information about the currently running process, the operating
system it is running on, the cloud provider hosting that operating system instance, or any number of other resource attributes.
resources := resource.New(context.Background(),
resource.WithFromEnv(), // pull attributes from OTEL_RESOURCE_ATTRIBUTES and OTEL_SERVICE_NAME environment variables
resource.WithProcess(), // This option configures a set of Detectors that discover process information
resource.WithDetectors(thirdparty.Detector{}), // Bring your own external Detector implementation
resource.WithAttributes(attribute.String("foo", "bar")), // Or specify resource attributes directly
)
OTLP Exporter
OpenTelemetry Protocol (OTLP) export is available in the go.opentelemetry.io/otel/exporters/otlp/otlptrace
and go.opentelemetry.io/otel/exporters/otlp/otlpmetrics
packages.
Please find more documentation on GitHub
Jaeger Exporter
Jaeger export is available in the go.opentelemetry.io/otel/exporters/jaeger
package.
Please find more documentation on GitHub
Prometheus Exporter
Prometheus export is available in the go.opentelemetry.io/otel/exporters/prometheus
package.
Please find more documentation on GitHub