Spring Web Autoconfiguration: add RestClient instrumentation

[Indaplace]

Hello,

It's possible to add the interceptor for RestClient as RestTemplate

Add a RestClientBeanPostProcessor, similar of RestTemplateBeanPostProcessor in

opentelemetry-java-instrumentation/instrumentation/spring/spring-boot-autoconfigure

import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.instrumentation.spring.web.v3_1.SpringWebTelemetry;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.web.client.RestClient;

public final class RestClientBeanPostProcessor implements BeanPostProcessor {

    private final ObjectProvider<OpenTelemetry> openTelemetryProvider;

    public RestClientBeanPostProcessor(ObjectProvider<OpenTelemetry> openTelemetryProvider) {
        this.openTelemetryProvider = openTelemetryProvider;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) {
        if (!(bean instanceof RestClient restClient)) {
            return bean;
        }
        ClientHttpRequestInterceptor interceptor = SpringWebTelemetry.create(openTelemetryProvider.getObject()).newInterceptor();
        return addRestClientInterceptorIfNotPresent(restClient, interceptor);
    }

    private static RestClient addRestClientInterceptorIfNotPresent(RestClient restClient, ClientHttpRequestInterceptor instrumentationInterceptor) {
        return restClient.mutate().requestInterceptors(interceptors -> {
            if (interceptors.stream().noneMatch(interceptor -> interceptor.getClass() == instrumentationInterceptor.getClass())) {
                interceptors.addFirst(instrumentationInterceptor);
            }
        }).build();
    }
}

Then create the bean with conditions in SpringWebInstrumentationAutoConfiguration

package io.opentelemetry.instrumentation.spring.autoconfigure.instrumentation.web;

import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.instrumentation.spring.autoconfigure.internal.SdkEnabled;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.client.RestClient;

@ConditionalOnBean(OpenTelemetry.class)
@ConditionalOnProperty(name = "otel.instrumentation.spring-web.enabled", matchIfMissing = true)
@Conditional(SdkEnabled.class)
@Configuration
public class SpringWebInstrumentationAutoConfiguration {

  public SpringWebInstrumentationAutoConfiguration() {}

  @ConditionalOnClass(RestTemplate.class)
  @Bean
  static RestTemplateBeanPostProcessor otelRestTemplateBeanPostProcessor(
      ObjectProvider<OpenTelemetry> openTelemetryProvider) {
    return new RestTemplateBeanPostProcessor(openTelemetryProvider);
  }

  @ConditionalOnClass(RestClient.class)
  @Bean
  static RestClientBeanPostProcessor otelRestClientBeanPostProcessor(ObjectProvider<OpenTelemetry> openTelemetryProvider) {
      return new RestClientBeanPostProcessor(openTelemetryProvider);
  }
}

Thanks !

Regards

[laurit]

@zeitlinger @jeanbisutti

[zeitlinger]

sounds great - feel free to create a PR 😄

[zeitlinger]

Created #10702