Allow registering TraceConfigSupplier and use it from zpages. (#2390)

* Allow registering TraceConfigSupplier and use it from zpages.

* Finish

* Remove unnecessary method

* Same method name

build.gradle

@@ -131,6 +131,9 @@ subprojects {
             it.options.errorprone.disable("JdkObsolete")
             it.options.errorprone.disable("UnnecessaryAnonymousClass")
 
+            // Limits APIs
+            it.options.errorprone.disable("NoFunctionalReturnType")
+
             it.options.compilerArgs += ["-Werror"]
         }
 

sdk-extensions/zpages/src/main/java/io/opentelemetry/sdk/extension/zpages/TraceConfigzZPageHandler.java

@@ -5,7 +5,6 @@
 
 package io.opentelemetry.sdk.extension.zpages;
 
-import io.opentelemetry.sdk.trace.SdkTracerManagement;
 import io.opentelemetry.sdk.trace.config.TraceConfig;
 import io.opentelemetry.sdk.trace.config.TraceConfigBuilder;
 import io.opentelemetry.sdk.trace.samplers.Sampler;
@@ -35,10 +34,10 @@ final class TraceConfigzZPageHandler extends ZPageHandler {
   // Background color used for zebra striping rows in table
   private static final String ZEBRA_STRIPE_COLOR = "#e6e6e6";
   private static final Logger logger = Logger.getLogger(TraceConfigzZPageHandler.class.getName());
-  private final SdkTracerManagement sdkTracerManagement;
+  private final TracezTraceConfigSupplier configSupplier;
 
-  TraceConfigzZPageHandler(SdkTracerManagement sdkTracerManagement) {
+  TraceConfigzZPageHandler(TracezTraceConfigSupplier configSupplier) {
-    this.sdkTracerManagement = sdkTracerManagement;
+    this.configSupplier = configSupplier;
   }
 
   @Override
@@ -211,45 +210,37 @@ final class TraceConfigzZPageHandler extends ZPageHandler {
     emitActiveTableRow(
         /* out= */ out,
         /* paramName= */ "Sampler",
-        /* paramValue=*/ this.sdkTracerManagement
+        /* paramValue=*/ configSupplier.get().getSampler().getDescription(),
-            .getActiveTraceConfig()
-            .getSampler()
-            .getDescription(),
         /* zebraStripeColor= */ ZEBRA_STRIPE_COLOR,
         /* zebraStripe= */ false);
     emitActiveTableRow(
         /* out= */ out,
         /* paramName= */ "MaxNumOfAttributes",
-        /* paramValue=*/ Integer.toString(
+        /* paramValue=*/ Integer.toString(configSupplier.get().getMaxNumberOfAttributes()),
-            this.sdkTracerManagement.getActiveTraceConfig().getMaxNumberOfAttributes()),
         /* zebraStripeColor= */ ZEBRA_STRIPE_COLOR,
         /* zebraStripe= */ true);
     emitActiveTableRow(
         /* out= */ out,
         /* paramName= */ "MaxNumOfEvents",
-        /* paramValue=*/ Integer.toString(
+        /* paramValue=*/ Integer.toString(configSupplier.get().getMaxNumberOfEvents()),
-            this.sdkTracerManagement.getActiveTraceConfig().getMaxNumberOfEvents()),
         /* zebraStripeColor= */ ZEBRA_STRIPE_COLOR,
         /* zebraStripe= */ false);
     emitActiveTableRow(
         /* out= */ out,
         /* paramName= */ "MaxNumOfLinks",
-        /* paramValue=*/ Integer.toString(
+        /* paramValue=*/ Integer.toString(configSupplier.get().getMaxNumberOfLinks()),
-            this.sdkTracerManagement.getActiveTraceConfig().getMaxNumberOfLinks()),
         /* zebraStripeColor= */ ZEBRA_STRIPE_COLOR,
         /* zebraStripe= */ true);
     emitActiveTableRow(
         /* out= */ out,
         /* paramName= */ "MaxNumOfAttributesPerEvent",
-        /* paramValue=*/ Integer.toString(
+        /* paramValue=*/ Integer.toString(configSupplier.get().getMaxNumberOfAttributesPerEvent()),
-            this.sdkTracerManagement.getActiveTraceConfig().getMaxNumberOfAttributesPerEvent()),
         /* zebraStripeColor= */ ZEBRA_STRIPE_COLOR,
         /* zebraStripe= */ false);
     emitActiveTableRow(
         /* out= */ out,
         /* paramName= */ "MaxNumOfAttributesPerLink",
-        /* paramValue=*/ Integer.toString(
+        /* paramValue=*/ Integer.toString(configSupplier.get().getMaxNumberOfAttributesPerLink()),
-            this.sdkTracerManagement.getActiveTraceConfig().getMaxNumberOfAttributesPerLink()),
         /* zebraStripeColor= */ ZEBRA_STRIPE_COLOR,
         /* zebraStripe=*/ true);
     out.print("</table>");
@@ -369,8 +360,7 @@ final class TraceConfigzZPageHandler extends ZPageHandler {
       return;
     }
     if (action.equals(QUERY_STRING_ACTION_CHANGE)) {
-      TraceConfigBuilder newConfigBuilder =
+      TraceConfigBuilder newConfigBuilder = configSupplier.get().toBuilder();
-          this.sdkTracerManagement.getActiveTraceConfig().toBuilder();
       String samplingProbabilityStr = queryMap.get(QUERY_STRING_SAMPLING_PROBABILITY);
       if (samplingProbabilityStr != null) {
         try {
@@ -435,10 +425,10 @@ final class TraceConfigzZPageHandler extends ZPageHandler {
               "MaxNumOfAttributesPerLink must be of the type integer", e);
         }
       }
-      this.sdkTracerManagement.updateActiveTraceConfig(newConfigBuilder.build());
+      configSupplier.setActiveTraceConfig(newConfigBuilder.build());
     } else if (action.equals(QUERY_STRING_ACTION_DEFAULT)) {
       TraceConfig defaultConfig = TraceConfig.getDefault().toBuilder().build();
-      this.sdkTracerManagement.updateActiveTraceConfig(defaultConfig);
+      configSupplier.setActiveTraceConfig(defaultConfig);
     }
   }
 }

sdk-extensions/zpages/src/main/java/io/opentelemetry/sdk/extension/zpages/TracezTraceConfigSupplier.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.extension.zpages;
+
+import io.opentelemetry.sdk.trace.config.TraceConfig;
+import java.util.function.Supplier;
+
+final class TracezTraceConfigSupplier implements Supplier<TraceConfig> {
+
+  private volatile TraceConfig activeTraceConfig;
+
+  TracezTraceConfigSupplier() {
+    activeTraceConfig = TraceConfig.getDefault();
+  }
+
+  @Override
+  public TraceConfig get() {
+    return activeTraceConfig;
+  }
+
+  void setActiveTraceConfig(TraceConfig traceConfig) {
+    activeTraceConfig = traceConfig;
+  }
+}

sdk-extensions/zpages/src/main/java/io/opentelemetry/sdk/extension/zpages/ZPageServer.java

@@ -6,19 +6,20 @@
 package io.opentelemetry.sdk.extension.zpages;
 
 import com.sun.net.httpserver.HttpServer;
-import io.opentelemetry.sdk.OpenTelemetrySdk;
-import io.opentelemetry.sdk.trace.SdkTracerManagement;
 import io.opentelemetry.sdk.trace.SpanProcessor;
+import io.opentelemetry.sdk.trace.config.TraceConfig;
 import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.util.Arrays;
+import java.util.function.Supplier;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
  * A collection of HTML pages to display stats and trace data and allow library configuration
- * control. To use, add {@linkplain ZPageServer#getSpanProcessor() the z-pages span processor} to a
+ * control. To use, add {@linkplain ZPageServer#getSpanProcessor() the z-pages span processor} and
+ * {@linkplain ZPageServer#getTracezTraceConfigSupplier() the z-pages dynamic trace config} to a
  * {@link io.opentelemetry.sdk.trace.SdkTracerProviderBuilder}. Currently all tracers can only be
  * made visible to a singleton {@link ZPageServer}.
  *
@@ -30,6 +31,7 @@ import javax.annotation.concurrent.ThreadSafe;
  *     OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
  *         .setTracerProvider(SdkTracerProvider.builder()
  *             .addSpanProcessor(ZPageServer.getSpanProcessor())
+ *             .setTraceConfigSupplier(ZPageServer.getTraceConfigSupplier())
  *             .build();
  *         .build();
  *
@@ -47,6 +49,7 @@ import javax.annotation.concurrent.ThreadSafe;
  *     OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
  *         .setTracerProvider(SdkTracerProvider.builder()
  *             .addSpanProcessor(ZPageServer.getSpanProcessor())
+ *             .setTraceConfigSupplier(ZPageServer.getTraceConfigSupplier())
  *             .build();
  *         .build();
  *
@@ -67,16 +70,16 @@ public final class ZPageServer {
   // Tracez SpanProcessor and DataAggregator for constructing TracezZPageHandler
   private static final TracezSpanProcessor tracezSpanProcessor =
       TracezSpanProcessor.builder().build();
+  private static final TracezTraceConfigSupplier tracezTraceConfigSupplier =
+      new TracezTraceConfigSupplier();
   private static final TracezDataAggregator tracezDataAggregator =
       new TracezDataAggregator(tracezSpanProcessor);
-  private static final SdkTracerManagement TRACER_SDK_MANAGEMENT =
-      OpenTelemetrySdk.getGlobalTracerManagement();
   // Handler for /tracez page
   private static final ZPageHandler tracezZPageHandler =
       new TracezZPageHandler(tracezDataAggregator);
   // Handler for /traceconfigz page
   private static final ZPageHandler traceConfigzZPageHandler =
-      new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+      new TraceConfigzZPageHandler(tracezTraceConfigSupplier);
   // Handler for index page, **please include all available ZPageHandlers in the constructor**
   private static final ZPageHandler indexZPageHandler =
       new IndexZPageHandler(Arrays.asList(tracezZPageHandler, traceConfigzZPageHandler));
@@ -87,6 +90,11 @@ public final class ZPageServer {
   @Nullable
   private static HttpServer server;
 
+  /** Returns a supplier of {@link TraceConfig} which can be reconfigured using zpages. */
+  public static Supplier<TraceConfig> getTracezTraceConfigSupplier() {
+    return tracezTraceConfigSupplier;
+  }
+
   /**
    * Returns a {@link SpanProcessor} which will allow processing of spans by {@link ZPageServer}.
    */

sdk-extensions/zpages/src/test/java/io/opentelemetry/sdk/extension/zpages/TraceConfigzZPageHandlerTest.java

@@ -8,8 +8,6 @@ package io.opentelemetry.sdk.extension.zpages;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.google.common.collect.ImmutableMap;
-import io.opentelemetry.sdk.OpenTelemetrySdk;
-import io.opentelemetry.sdk.trace.SdkTracerManagement;
 import io.opentelemetry.sdk.trace.config.TraceConfig;
 import io.opentelemetry.sdk.trace.samplers.Sampler;
 import java.io.ByteArrayOutputStream;
@@ -18,35 +16,14 @@ import java.util.Map;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-/** Unit tests for {@link TraceConfigzZPageHandler}. */
+class TraceConfigzZPageHandlerTest {
-public final class TraceConfigzZPageHandlerTest {
-  private static final SdkTracerManagement TRACER_SDK_MANAGEMENT =
-      OpenTelemetrySdk.getGlobalTracerManagement();
   private static final Map<String, String> emptyQueryMap = ImmutableMap.of();
 
+  private TracezTraceConfigSupplier configSupplier;
+
   @BeforeEach
   void setup() {
-    // Restore default config
+    configSupplier = new TracezTraceConfigSupplier();
-    OutputStream output = new ByteArrayOutputStream();
-    Map<String, String> queryMap = ImmutableMap.of("action", "default");
-
-    TraceConfigzZPageHandler traceConfigzZPageHandler =
-        new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
-    traceConfigzZPageHandler.processRequest("POST", queryMap, output);
-    traceConfigzZPageHandler.emitHtml(queryMap, output);
-
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getSampler().getDescription())
-        .isEqualTo(TraceConfig.getDefault().getSampler().getDescription());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributes())
-        .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributes());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfEvents())
-        .isEqualTo(TraceConfig.getDefault().getMaxNumberOfEvents());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfLinks())
-        .isEqualTo(TraceConfig.getDefault().getMaxNumberOfLinks());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerEvent())
-        .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributesPerEvent());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerLink())
-        .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributesPerLink());
   }
 
   @Test
@@ -60,7 +37,7 @@ public final class TraceConfigzZPageHandlerTest {
     String queryMaxNumOfAttributesPerLink = "maxnumofattributesperlink";
 
     TraceConfigzZPageHandler traceConfigzZPageHandler =
-        new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+        new TraceConfigzZPageHandler(configSupplier);
     traceConfigzZPageHandler.emitHtml(emptyQueryMap, output);
 
     assertThat(output.toString()).contains("SamplingProbability to");
@@ -101,48 +78,29 @@ public final class TraceConfigzZPageHandlerTest {
     OutputStream output = new ByteArrayOutputStream();
 
     TraceConfigzZPageHandler traceConfigzZPageHandler =
-        new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+        new TraceConfigzZPageHandler(configSupplier);
     traceConfigzZPageHandler.emitHtml(emptyQueryMap, output);
 
     assertThat(output.toString()).contains("Sampler");
     assertThat(output.toString())
-        .contains(
+        .contains(">" + configSupplier.get().getSampler().getDescription() + "<");
-            ">" + TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getSampler().getDescription() + "<");
     assertThat(output.toString()).contains("MaxNumberOfAttributes");
     assertThat(output.toString())
-        .contains(
+        .contains(">" + Integer.toString(configSupplier.get().getMaxNumberOfAttributes()) + "<");
-            ">"
-                + Integer.toString(
-                    TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributes())
-                + "<");
     assertThat(output.toString()).contains("MaxNumberOfEvents");
     assertThat(output.toString())
-        .contains(
+        .contains(">" + Integer.toString(configSupplier.get().getMaxNumberOfEvents()) + "<");
-            ">"
-                + Integer.toString(
-                    TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfEvents())
-                + "<");
     assertThat(output.toString()).contains("MaxNumberOfLinks");
     assertThat(output.toString())
-        .contains(
+        .contains(">" + Integer.toString(configSupplier.get().getMaxNumberOfLinks()) + "<");
-            ">"
-                + Integer.toString(
-                    TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfLinks())
-                + "<");
     assertThat(output.toString()).contains("MaxNumberOfAttributesPerEvent");
     assertThat(output.toString())
         .contains(
-            ">"
+            ">" + Integer.toString(configSupplier.get().getMaxNumberOfAttributesPerEvent()) + "<");
-                + Integer.toString(
-                    TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerEvent())
-                + "<");
     assertThat(output.toString()).contains("MaxNumberOfAttributesPerLink");
     assertThat(output.toString())
         .contains(
-            ">"
+            ">" + Integer.toString(configSupplier.get().getMaxNumberOfAttributesPerLink()) + "<");
-                + Integer.toString(
-                    TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerLink())
-                + "<");
   }
 
   @Test
@@ -173,22 +131,22 @@ public final class TraceConfigzZPageHandlerTest {
             .build();
 
     TraceConfigzZPageHandler traceConfigzZPageHandler =
-        new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+        new TraceConfigzZPageHandler(configSupplier);
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
     traceConfigzZPageHandler.emitHtml(queryMap, output);
 
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getSampler().getDescription())
+    assertThat(configSupplier.get().getSampler().getDescription())
         .isEqualTo(
             Sampler.traceIdRatioBased(Double.parseDouble(newSamplingProbability)).getDescription());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributes())
+    assertThat(configSupplier.get().getMaxNumberOfAttributes())
         .isEqualTo(Integer.parseInt(newMaxNumOfAttributes));
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfEvents())
+    assertThat(configSupplier.get().getMaxNumberOfEvents())
         .isEqualTo(Integer.parseInt(newMaxNumOfEvents));
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfLinks())
+    assertThat(configSupplier.get().getMaxNumberOfLinks())
         .isEqualTo(Integer.parseInt(newMaxNumOfLinks));
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerEvent())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerEvent())
         .isEqualTo(Integer.parseInt(newMaxNumOfAttributesPerEvent));
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerLink())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerLink())
         .isEqualTo(Integer.parseInt(newMaxNumOfAttributesPerLink));
   }
 
@@ -199,21 +157,21 @@ public final class TraceConfigzZPageHandlerTest {
     Map<String, String> queryMap = ImmutableMap.of("action", "default");
 
     TraceConfigzZPageHandler traceConfigzZPageHandler =
-        new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+        new TraceConfigzZPageHandler(configSupplier);
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
     traceConfigzZPageHandler.emitHtml(queryMap, output);
 
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getSampler().getDescription())
+    assertThat(configSupplier.get().getSampler().getDescription())
         .isEqualTo(TraceConfig.getDefault().getSampler().getDescription());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributes())
+    assertThat(configSupplier.get().getMaxNumberOfAttributes())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributes());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfEvents())
+    assertThat(configSupplier.get().getMaxNumberOfEvents())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfEvents());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfLinks())
+    assertThat(configSupplier.get().getMaxNumberOfLinks())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfLinks());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerEvent())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerEvent())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributesPerEvent());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerLink())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerLink())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributesPerLink());
   }
 
@@ -224,21 +182,21 @@ public final class TraceConfigzZPageHandlerTest {
     Map<String, String> queryMap = ImmutableMap.of("action", "change");
 
     TraceConfigzZPageHandler traceConfigzZPageHandler =
-        new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+        new TraceConfigzZPageHandler(configSupplier);
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
     traceConfigzZPageHandler.emitHtml(queryMap, output);
 
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getSampler().getDescription())
+    assertThat(configSupplier.get().getSampler().getDescription())
         .isEqualTo(TraceConfig.getDefault().getSampler().getDescription());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributes())
+    assertThat(configSupplier.get().getMaxNumberOfAttributes())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributes());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfEvents())
+    assertThat(configSupplier.get().getMaxNumberOfEvents())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfEvents());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfLinks())
+    assertThat(configSupplier.get().getMaxNumberOfLinks())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfLinks());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerEvent())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerEvent())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributesPerEvent());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerLink())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerLink())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributesPerLink());
   }
 
@@ -247,7 +205,7 @@ public final class TraceConfigzZPageHandlerTest {
     // Invalid samplingProbability (not type of double)
     OutputStream output = new ByteArrayOutputStream();
     TraceConfigzZPageHandler traceConfigzZPageHandler =
-        new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+        new TraceConfigzZPageHandler(configSupplier);
     Map<String, String> queryMap =
         ImmutableMap.of("action", "change", "samplingprobability", "invalid");
 
@@ -258,7 +216,7 @@ public final class TraceConfigzZPageHandlerTest {
 
     // Invalid samplingProbability (< 0)
     output = new ByteArrayOutputStream();
-    traceConfigzZPageHandler = new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+    traceConfigzZPageHandler = new TraceConfigzZPageHandler(configSupplier);
     queryMap = ImmutableMap.of("action", "change", "samplingprobability", "-1");
 
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
@@ -268,7 +226,7 @@ public final class TraceConfigzZPageHandlerTest {
 
     // Invalid samplingProbability (> 1)
     output = new ByteArrayOutputStream();
-    traceConfigzZPageHandler = new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+    traceConfigzZPageHandler = new TraceConfigzZPageHandler(configSupplier);
     queryMap = ImmutableMap.of("action", "change", "samplingprobability", "1.1");
 
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
@@ -278,7 +236,7 @@ public final class TraceConfigzZPageHandlerTest {
 
     // Invalid maxNumOfAttributes
     output = new ByteArrayOutputStream();
-    traceConfigzZPageHandler = new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+    traceConfigzZPageHandler = new TraceConfigzZPageHandler(configSupplier);
     queryMap = ImmutableMap.of("action", "change", "maxnumofattributes", "invalid");
 
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
@@ -288,7 +246,7 @@ public final class TraceConfigzZPageHandlerTest {
 
     // Invalid maxNumOfEvents
     output = new ByteArrayOutputStream();
-    traceConfigzZPageHandler = new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+    traceConfigzZPageHandler = new TraceConfigzZPageHandler(configSupplier);
     queryMap = ImmutableMap.of("action", "change", "maxnumofevents", "invalid");
 
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
@@ -298,7 +256,7 @@ public final class TraceConfigzZPageHandlerTest {
 
     // Invalid maxNumLinks
     output = new ByteArrayOutputStream();
-    traceConfigzZPageHandler = new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+    traceConfigzZPageHandler = new TraceConfigzZPageHandler(configSupplier);
     queryMap = ImmutableMap.of("action", "change", "maxnumoflinks", "invalid");
 
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
@@ -308,7 +266,7 @@ public final class TraceConfigzZPageHandlerTest {
 
     // Invalid maxNumOfAttributesPerEvent
     output = new ByteArrayOutputStream();
-    traceConfigzZPageHandler = new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+    traceConfigzZPageHandler = new TraceConfigzZPageHandler(configSupplier);
     queryMap = ImmutableMap.of("action", "change", "maxnumofattributesperevent", "invalid");
 
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
@@ -319,7 +277,7 @@ public final class TraceConfigzZPageHandlerTest {
 
     // Invalid maxNumOfAttributesPerLink
     output = new ByteArrayOutputStream();
-    traceConfigzZPageHandler = new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+    traceConfigzZPageHandler = new TraceConfigzZPageHandler(configSupplier);
     queryMap = ImmutableMap.of("action", "change", "maxnumofattributesperlink", "invalid");
 
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
@@ -357,40 +315,40 @@ public final class TraceConfigzZPageHandlerTest {
             .build();
 
     TraceConfigzZPageHandler traceConfigzZPageHandler =
-        new TraceConfigzZPageHandler(TRACER_SDK_MANAGEMENT);
+        new TraceConfigzZPageHandler(configSupplier);
 
     // GET request, Should not apply changes
     traceConfigzZPageHandler.emitHtml(queryMap, output);
 
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getSampler().getDescription())
+    assertThat(configSupplier.get().getSampler().getDescription())
         .isEqualTo(TraceConfig.getDefault().getSampler().getDescription());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributes())
+    assertThat(configSupplier.get().getMaxNumberOfAttributes())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributes());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfEvents())
+    assertThat(configSupplier.get().getMaxNumberOfEvents())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfEvents());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfLinks())
+    assertThat(configSupplier.get().getMaxNumberOfLinks())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfLinks());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerEvent())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerEvent())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributesPerEvent());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerLink())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerLink())
         .isEqualTo(TraceConfig.getDefault().getMaxNumberOfAttributesPerLink());
 
     // POST request, Should apply changes
     traceConfigzZPageHandler.processRequest("POST", queryMap, output);
     traceConfigzZPageHandler.emitHtml(queryMap, output);
 
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getSampler().getDescription())
+    assertThat(configSupplier.get().getSampler().getDescription())
         .isEqualTo(
             Sampler.traceIdRatioBased(Double.parseDouble(newSamplingProbability)).getDescription());
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributes())
+    assertThat(configSupplier.get().getMaxNumberOfAttributes())
         .isEqualTo(Integer.parseInt(newMaxNumOfAttributes));
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfEvents())
+    assertThat(configSupplier.get().getMaxNumberOfEvents())
         .isEqualTo(Integer.parseInt(newMaxNumOfEvents));
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfLinks())
+    assertThat(configSupplier.get().getMaxNumberOfLinks())
         .isEqualTo(Integer.parseInt(newMaxNumOfLinks));
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerEvent())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerEvent())
         .isEqualTo(Integer.parseInt(newMaxNumOfAttributesPerEvent));
-    assertThat(TRACER_SDK_MANAGEMENT.getActiveTraceConfig().getMaxNumberOfAttributesPerLink())
+    assertThat(configSupplier.get().getMaxNumberOfAttributesPerLink())
         .isEqualTo(Integer.parseInt(newMaxNumOfAttributesPerLink));
   }
 }

sdk-extensions/zpages/src/test/java/io/opentelemetry/sdk/extension/zpages/ZPageServerTest.java

@@ -15,4 +15,10 @@ class ZPageServerTest {
   void spanProcessor() {
     assertThat(ZPageServer.getSpanProcessor()).isInstanceOf(TracezSpanProcessor.class);
   }
+
+  @Test
+  void traceConfigSupplier() {
+    assertThat(ZPageServer.getTracezTraceConfigSupplier())
+        .isInstanceOf(TracezTraceConfigSupplier.class);
+  }
 }

sdk/all/src/test/java/io/opentelemetry/sdk/OpenTelemetrySdkTest.java

@@ -118,15 +118,18 @@ class OpenTelemetrySdkTest {
     TracerProvider unobfuscatedTracerProvider =
         ((ObfuscatedTracerProvider) openTelemetry.getTracerProvider()).unobfuscate();
 
-    assertThat(unobfuscatedTracerProvider).isInstanceOf(SdkTracerProvider.class);
+    assertThat(unobfuscatedTracerProvider)
+        .isInstanceOfSatisfying(
+            SdkTracerProvider.class,
+            sdkTracerProvider ->
+                assertThat(sdkTracerProvider.getActiveTraceConfig()).isEqualTo(traceConfig));
     // Since TracerProvider is in a different package, the only alternative to this reflective
     // approach would be to make the fields public for testing which is worse than this.
     assertThat(unobfuscatedTracerProvider)
         .extracting("sharedState")
         .hasFieldOrPropertyWithValue("clock", clock)
         .hasFieldOrPropertyWithValue("resource", resource)
-        .hasFieldOrPropertyWithValue("idGenerator", idGenerator)
+        .hasFieldOrPropertyWithValue("idGenerator", idGenerator);
-        .hasFieldOrPropertyWithValue("activeTraceConfig", traceConfig);
   }
 
   @Test

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/SdkTracerProvider.java

@@ -14,6 +14,7 @@ import io.opentelemetry.sdk.internal.ComponentRegistry;
 import io.opentelemetry.sdk.resources.Resource;
 import io.opentelemetry.sdk.trace.config.TraceConfig;
 import java.util.List;
+import java.util.function.Supplier;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.annotation.Nullable;
@@ -44,10 +45,10 @@ public final class SdkTracerProvider implements TracerProvider, SdkTracerManagem
       Clock clock,
       IdGenerator idsGenerator,
       Resource resource,
-      TraceConfig traceConfig,
+      Supplier<TraceConfig> traceConfigSupplier,
       List<SpanProcessor> spanProcessors) {
     this.sharedState =
-        new TracerSharedState(clock, idsGenerator, resource, traceConfig, spanProcessors);
+        new TracerSharedState(clock, idsGenerator, resource, traceConfigSupplier, spanProcessors);
     this.tracerSdkComponentRegistry =
         new ComponentRegistry<>(
             instrumentationLibraryInfo -> new SdkTracer(sharedState, instrumentationLibraryInfo));

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/SdkTracerProviderBuilder.java

@@ -13,6 +13,7 @@ import io.opentelemetry.sdk.resources.Resource;
 import io.opentelemetry.sdk.trace.config.TraceConfig;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Supplier;
 
 /** Builder of {@link SdkTracerProvider}. */
 public final class SdkTracerProviderBuilder {
@@ -21,7 +22,7 @@ public final class SdkTracerProviderBuilder {
   private Clock clock = SystemClock.getInstance();
   private IdGenerator idsGenerator = IdGenerator.random();
   private Resource resource = Resource.getDefault();
-  private TraceConfig traceConfig = TraceConfig.getDefault();
+  private Supplier<TraceConfig> traceConfigSupplier = TraceConfig::getDefault;
 
   /**
    * Assign a {@link Clock}.
@@ -67,7 +68,19 @@ public final class SdkTracerProviderBuilder {
    */
   public SdkTracerProviderBuilder setTraceConfig(TraceConfig traceConfig) {
     requireNonNull(traceConfig, "traceConfig");
-    this.traceConfig = traceConfig;
+    this.traceConfigSupplier = () -> traceConfig;
+    return this;
+  }
+
+  /**
+   * Assign a {@link Supplier} of {@link TraceConfig}. {@link TraceConfig} will be retrieved each
+   * time a {@link io.opentelemetry.api.trace.Span} is started.
+   *
+   * @return this
+   */
+  public SdkTracerProviderBuilder setTraceConfig(Supplier<TraceConfig> traceConfigSupplier) {
+    requireNonNull(traceConfigSupplier, "traceConfig");
+    this.traceConfigSupplier = traceConfigSupplier;
     return this;
   }
 
@@ -87,7 +100,8 @@ public final class SdkTracerProviderBuilder {
    * @return An initialized TraceSdkProvider.
    */
   public SdkTracerProvider build() {
-    return new SdkTracerProvider(clock, idsGenerator, resource, traceConfig, spanProcessors);
+    return new SdkTracerProvider(
+        clock, idsGenerator, resource, traceConfigSupplier, spanProcessors);
   }
 
   SdkTracerProviderBuilder() {}

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/TracerSharedState.java

@@ -11,6 +11,7 @@ import io.opentelemetry.sdk.trace.config.TraceConfig;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
 import javax.annotation.concurrent.GuardedBy;
 
 // Represents the shared state/config between all Tracers created by the same TracerProvider.
@@ -22,7 +23,7 @@ final class TracerSharedState {
 
   // Reads and writes are atomic for reference variables. Use volatile to ensure that these
   // operations are visible on other CPUs as well.
-  private volatile TraceConfig activeTraceConfig;
+  private volatile Supplier<TraceConfig> traceConfigSupplier;
   private volatile SpanProcessor activeSpanProcessor = NoopSpanProcessor.getInstance();
   private volatile boolean isStopped = false;
 
@@ -33,12 +34,12 @@ final class TracerSharedState {
       Clock clock,
       IdGenerator idGenerator,
       Resource resource,
-      TraceConfig traceConfig,
+      Supplier<TraceConfig> traceConfigSupplier,
       List<SpanProcessor> spanProcessors) {
     this.clock = clock;
     this.idGenerator = idGenerator;
     this.resource = resource;
-    this.activeTraceConfig = traceConfig;
+    this.traceConfigSupplier = traceConfigSupplier;
     this.registeredSpanProcessors = new ArrayList<>(spanProcessors);
     activeSpanProcessor = SpanProcessor.composite(registeredSpanProcessors);
   }
@@ -61,7 +62,7 @@ final class TracerSharedState {
    * @return the active {@code TraceConfig}.
    */
   TraceConfig getActiveTraceConfig() {
-    return activeTraceConfig;
+    return traceConfigSupplier.get();
   }
 
   /**
@@ -70,7 +71,7 @@ final class TracerSharedState {
    * @param traceConfig the new active {@code TraceConfig}.
    */
   void updateActiveTraceConfig(TraceConfig traceConfig) {
-    activeTraceConfig = traceConfig;
+    traceConfigSupplier = () -> traceConfig;
   }
 
   /**

sdk/trace/src/test/java/io/opentelemetry/sdk/trace/SdkTracerProviderTest.java

@@ -18,6 +18,7 @@ import io.opentelemetry.sdk.common.InstrumentationLibraryInfo;
 import io.opentelemetry.sdk.resources.Resource;
 import io.opentelemetry.sdk.trace.config.TraceConfig;
 import io.opentelemetry.sdk.trace.samplers.Sampler;
+import java.util.function.Supplier;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -55,7 +56,15 @@ class SdkTracerProviderTest {
 
   @Test
   void builder_NullTraceConfig() {
-    assertThatThrownBy(() -> SdkTracerProvider.builder().setTraceConfig(null))
+    assertThatThrownBy(() -> SdkTracerProvider.builder().setTraceConfig((TraceConfig) null))
+        .isInstanceOf(NullPointerException.class)
+        .hasMessage("traceConfig");
+  }
+
+  @Test
+  void builder_NullTraceConfigSupplier() {
+    assertThatThrownBy(
+            () -> SdkTracerProvider.builder().setTraceConfig((Supplier<TraceConfig>) null))
         .isInstanceOf(NullPointerException.class)
         .hasMessage("traceConfig");
   }