Package brave.baggage

Class BaggagePropagation<K>

  • All Implemented Interfaces:
    Propagation<K>
    public final class BaggagePropagation<K>
extends Object
implements Propagation<K>
    This implements in-process and remote baggage propagation.

    For example, if you have a need to know the a specific request's country code, you can propagate it through the trace as HTTP headers. 

    
 import brave.baggage.BaggagePropagationConfig.SingleBaggageField;

 // Configure your baggage field
 COUNTRY_CODE = BaggageField.create("country-code");

 // When you initialize the builder, add the baggage you want to propagate
 tracingBuilder.propagationFactory(
   BaggagePropagation.newFactoryBuilder(B3Propagation.FACTORY)
                     .add(SingleBaggageField.remote(COUNTRY_CODE))
                     .build()
 );

 // later, you can tag that country code
 Tags.BAGGAGE_FIELD.tag(COUNTRY_CODE, span);

    See BaggageField for baggage usage examples.

    Customizing propagation keys

    BaggagePropagationConfig.SingleBaggageField.remote(BaggageField) sets the name used as a propagation key (header) to the lowercase variant of the field name. You can override this by supplying different key names. Note: they will be lower-cased.

    For example, the following will propagate the field "x-vcap-request-id" as-is, but send the fields "countryCode" and "userId" on the wire as "baggage-country-code" and "baggage-user-id" respectively. 

    
 import brave.baggage.BaggagePropagationConfig.SingleBaggageField;

 REQUEST_ID = BaggageField.create("x-vcap-request-id");
 COUNTRY_CODE = BaggageField.create("countryCode");
 USER_ID = BaggageField.create("userId");

 tracingBuilder.propagationFactory(
     BaggagePropagation.newFactoryBuilder(B3Propagation.FACTORY)
                       .add(SingleBaggageField.remote(REQUEST_ID))
                       .add(SingleBaggageField.newBuilder(COUNTRY_CODE)
                                              .addKeyName("baggage-country-code").build())
                       .add(SingleBaggageField.newBuilder(USER_ID)
                                              .addKeyName("baggage-user-id").build())
                       .build()
 );
    Since:
    5.11
    See Also:
    BaggageField, BaggagePropagationConfig, BaggagePropagationCustomizer, CorrelationScopeDecorator