Provide an api to configure propagation for spring servlet and client (#1924)

* Provide an api to configure propagation method for spring servlet and client.

* fix checkerframework error.

* use enum for propagation.

* use javax.annotations.Nullable

Author: rghetia

contrib/spring/src/main/java/io/opencensus/contrib/spring/autoconfig/OpenCensusProperties.java

@@ -16,6 +16,8 @@
 
 package io.opencensus.contrib.spring.autoconfig;
 
+import static io.opencensus.contrib.spring.autoconfig.OpenCensusProperties.Trace.Propagation.TRACE_PROPAGATION_TRACE_CONTEXT;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -27,6 +29,7 @@
 public class OpenCensusProperties {
 
   private boolean enabled = true;
+  private Trace trace = new Trace();
 
   public boolean isEnabled() {
     return this.enabled;
@@ -35,4 +38,55 @@ public boolean isEnabled() {
   public void setEnabled(boolean enabled) {
     this.enabled = enabled;
   }
+
+  public Trace getTrace() {
+    return this.trace;
+  }
+
+  public void setTrace(Trace trace) {
+    this.trace = trace;
+  }
+
+  /**
+   * Trace properties.
+   *
+   * @since 0.23
+   */
+  public static final class Trace {
+
+    public enum Propagation {
+      /**
+       * Specifies Trace Context format for span context propagation.
+       *
+       * @since 0.23
+       */
+      TRACE_PROPAGATION_TRACE_CONTEXT,
+
+      /**
+       * Specifies B3 format for span context propagation.
+       *
+       * @since 0.23
+       */
+      TRACE_PROPAGATION_B3,
+    }
+
+    private Propagation propagation = TRACE_PROPAGATION_TRACE_CONTEXT;
+    private boolean publicEndpoint = false;
+
+    public Propagation getPropagation() {
+      return propagation;
+    }
+
+    public void setPropagation(Propagation propagation) {
+      this.propagation = propagation;
+    }
+
+    public boolean isPublicEndpoint() {
+      return publicEndpoint;
+    }
+
+    public void setPublicEndpoint(boolean publicEndpoint) {
+      this.publicEndpoint = publicEndpoint;
+    }
+  }
 }

contrib/spring/src/main/java/io/opencensus/contrib/spring/autoconfig/TraceWebAsyncClientAutoConfiguration.java

@@ -17,12 +17,18 @@
 package io.opencensus.contrib.spring.autoconfig;
 
 import io.opencensus.common.ExperimentalApi;
+import io.opencensus.contrib.http.HttpExtractor;
+import io.opencensus.contrib.spring.autoconfig.OpenCensusProperties.Trace;
+import io.opencensus.contrib.spring.autoconfig.OpenCensusProperties.Trace.Propagation;
 import io.opencensus.contrib.spring.instrument.web.client.TracingAsyncClientHttpRequestInterceptor;
+import io.opencensus.trace.Tracing;
+import io.opencensus.trace.propagation.TextFormat;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import javax.annotation.PostConstruct;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -31,6 +37,8 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.http.HttpRequest;
+import org.springframework.http.client.ClientHttpResponse;
 
 /**
  * {@link org.springframework.boot.autoconfigure.EnableAutoConfiguration Auto-configuration} enables
@@ -49,12 +57,26 @@
 public class TraceWebAsyncClientAutoConfiguration {
   @Configuration
   @ConditionalOnBean(org.springframework.web.client.AsyncRestTemplate.class)
+  @SuppressWarnings("initialization.fields.uninitialized")
   static class AsyncRestTemplateCfg {
 
+    @Value("${opencensus.spring.trace.propagation:TRACE_PROPAGATION_TRACE_CONTEXT}")
+    private Trace.Propagation propagation;
+
+    @Autowired(required = false)
+    HttpExtractor<HttpRequest, ClientHttpResponse> extractor;
+
     @Bean
     public TracingAsyncClientHttpRequestInterceptor asyncTracingClientHttpRequestInterceptor() {
+      TextFormat propagator;
+
+      if (propagation != null && propagation == Propagation.TRACE_PROPAGATION_B3) {
+        propagator = Tracing.getPropagationComponent().getB3Format();
+      } else {
+        propagator = Tracing.getPropagationComponent().getTraceContextFormat();
+      }
       return (TracingAsyncClientHttpRequestInterceptor)
-          TracingAsyncClientHttpRequestInterceptor.create();
+          TracingAsyncClientHttpRequestInterceptor.create(propagator, extractor);
     }
   }
 

contrib/spring/src/main/java/io/opencensus/contrib/spring/instrument/web/HttpServletFilter.java

@@ -19,11 +19,38 @@
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import io.opencensus.contrib.http.servlet.OcHttpServletFilter;
 import io.opencensus.contrib.spring.autoconfig.OpenCensusAutoConfiguration;
+import io.opencensus.contrib.spring.autoconfig.OpenCensusProperties.Trace;
+import io.opencensus.contrib.spring.autoconfig.OpenCensusProperties.Trace.Propagation;
+import io.opencensus.trace.Tracing;
 import javax.servlet.Filter;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletContext;
+import javax.servlet.ServletException;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.core.annotation.Order;
 import org.springframework.stereotype.Component;
 
 @Component
 @Order(OpenCensusAutoConfiguration.TRACE_FILTER_ORDER)
 @SuppressFBWarnings("RI_REDUNDANT_INTERFACES")
-public class HttpServletFilter extends OcHttpServletFilter implements Filter {}
+@SuppressWarnings("initialization.fields.uninitialized")
+public class HttpServletFilter extends OcHttpServletFilter implements Filter {
+
+  @Value("${opencensus.spring.trace.propagation:TRACE_PROPAGATION_TRACE_CONTEXT}")
+  private Trace.Propagation propagation;
+
+  @Value("${opencensus.spring.trace.publicEndpoint:false}")
+  private Boolean publicEndpoint;
+
+  @Override
+  public void init(FilterConfig filterConfig) throws ServletException {
+    ServletContext context = filterConfig.getServletContext();
+    if (propagation != null && propagation == Propagation.TRACE_PROPAGATION_B3) {
+      context.setAttribute(OC_TRACE_PROPAGATOR, Tracing.getPropagationComponent().getB3Format());
+    }
+    if (publicEndpoint) {
+      context.setInitParameter(OC_PUBLIC_ENDPOINT, publicEndpoint.toString());
+    }
+    super.init(filterConfig);
+  }
+}

contrib/spring/src/main/java/io/opencensus/contrib/spring/instrument/web/client/TracingAsyncClientHttpRequestInterceptor.java

@@ -23,6 +23,7 @@
 import io.opencensus.contrib.http.HttpRequestContext;
 import io.opencensus.trace.Tracer;
 import io.opencensus.trace.Tracing;
+import io.opencensus.trace.propagation.TextFormat;
 import io.opencensus.trace.propagation.TextFormat.Setter;
 import java.io.IOException;
 import java.net.MalformedURLException;
@@ -57,22 +58,36 @@ public void put(HttpRequest carrier, String key, String value) {
   /**
    * Create an instance of {@code TracingAsyncClientHttpRequestInterceptor}.
    *
+   * @param extractor {@link HttpExtractor} to extract request and response specific attributes. If
+   *     it is null then default extractor is used.
+   * @param propagator {@link TextFormat} to propagate trace context to remote peer. If it is null
+   *     then default propagator (TraceContextFormat) is used.
    * @return {@code TracingAsyncClientHttpRequestInterceptor}
    * @since 0.23.0
    */
-  public static TracingAsyncClientHttpRequestInterceptor create() {
-    return new TracingAsyncClientHttpRequestInterceptor();
+  public static TracingAsyncClientHttpRequestInterceptor create(
+      @Nullable TextFormat propagator,
+      @Nullable HttpExtractor<HttpRequest, ClientHttpResponse> extractor) {
+    return new TracingAsyncClientHttpRequestInterceptor(propagator, extractor);
   }
 
-  TracingAsyncClientHttpRequestInterceptor() {
+  TracingAsyncClientHttpRequestInterceptor(
+      @Nullable TextFormat propagator,
+      @Nullable HttpExtractor<HttpRequest, ClientHttpResponse> extractor) {
 
     tracer = Tracing.getTracer();
+
+    if (propagator == null) {
+      propagator = Tracing.getPropagationComponent().getTraceContextFormat();
+    }
+
+    if (extractor == null) {
+      extractor = (HttpExtractor<HttpRequest, ClientHttpResponse>) new HttpClientExtractor();
+    }
+
     handler =
         new HttpClientHandler<HttpRequest, ClientHttpResponse, HttpRequest>(
-            Tracing.getTracer(),
-            new HttpClientExtractor(),
-            Tracing.getPropagationComponent().getTraceContextFormat(),
-            setter);
+            Tracing.getTracer(), extractor, propagator, setter);
   }
 
   /**