Merge pull request #827 from DataDog/labbati/hostname

Detect hostname

Author: labbati

CONTRIBUTING.md

@@ -20,8 +20,8 @@ Other source files (Groovy, Scala, etc) should ideally be formatted by Intellij
 Suggested plugins and settings:
 
 * Editor > Code Style > Java/Groovy > Imports
-  * Class count to use import with '*': `10` (some number sufficiently large that is unlikely to matter)
-  * Names count to use static import with '*': `10`
+  * Class count to use import with '*': `50` (some number sufficiently large that is unlikely to matter)
+  * Names count to use static import with '*': `50`
   * With java use the following import layout (groovy should still use the default) to ensure consistency with google-java-format:
     ![import layout](https://user-images.githubusercontent.com/734411/43430811-28442636-94ae-11e8-86f1-f270ddcba023.png)
 * [Google Java Format](https://plugins.jetbrains.com/plugin/8527-google-java-format)

dd-trace-api/src/main/java/datadog/trace/api/Config.java

@@ -1,5 +1,7 @@
 package datadog.trace.api;
 
+import java.net.InetAddress;
+import java.net.UnknownHostException;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
@@ -51,6 +53,7 @@ public class Config {
   public static final String TRACE_ANNOTATIONS = "trace.annotations";
   public static final String TRACE_METHODS = "trace.methods";
   public static final String TRACE_CLASSES_EXCLUDE = "trace.classes.exclude";
+  public static final String TRACE_REPORT_HOSTNAME = "trace.report-hostname";
   public static final String HEADER_TAGS = "trace.header.tags";
   public static final String HTTP_SERVER_ERROR_STATUSES = "http.server.error.statuses";
   public static final String HTTP_CLIENT_ERROR_STATUSES = "http.client.error.statuses";
@@ -105,11 +108,16 @@ public class Config {
 
   private static final String SPLIT_BY_SPACE_OR_COMMA_REGEX = "[,\\s]+";
 
+  private static final boolean DEFAULT_TRACE_REPORT_HOSTNAME = false;
+
   public enum PropagationStyle {
     DATADOG,
     B3
   }
 
+  /** A tag intended for internal use only, hence not added to the public api DDTags class. */
+  private static final String INTERNAL_HOST_NAME = "_dd.hostname";
+
   /**
    * this is a random UUID that gets generated on JVM start up and is attached to every root span
    * and every JMX metric that is sent out.
@@ -147,6 +155,8 @@ public enum PropagationStyle {
 
   @Getter private final boolean logsInjectionEnabled;
 
+  @Getter private final boolean reportHostName;
+
   // Read order: System Properties -> Env Variables, [-> default value]
   // Visible for testing
   Config() {
@@ -221,6 +231,9 @@ public enum PropagationStyle {
     logsInjectionEnabled =
         getBooleanSettingFromEnvironment(LOGS_INJECTION_ENABLED, DEFAULT_LOGS_INJECTION_ENABLED);
 
+    reportHostName =
+        getBooleanSettingFromEnvironment(TRACE_REPORT_HOSTNAME, DEFAULT_TRACE_REPORT_HOSTNAME);
+
     log.debug("New instance: {}", this);
   }
 
@@ -301,9 +314,24 @@ private Config(final Properties properties, final Config parent) {
     logsInjectionEnabled =
         getBooleanSettingFromEnvironment(LOGS_INJECTION_ENABLED, DEFAULT_LOGS_INJECTION_ENABLED);
 
+    reportHostName =
+        getPropertyBooleanValue(properties, TRACE_REPORT_HOSTNAME, parent.reportHostName);
+
     log.debug("New instance: {}", this);
   }
 
+  /** @return A map of tags to be applied only to the local application root span. */
+  public Map<String, String> getLocalRootSpanTags() {
+    final Map<String, String> runtimeTags = getRuntimeTags();
+    final Map<String, String> result =
+        newHashMap(reportHostName ? (runtimeTags.size() + 1) : runtimeTags.size());
+    result.putAll(runtimeTags);
+    if (reportHostName) {
+      result.put(INTERNAL_HOST_NAME, getHostname());
+    }
+    return Collections.unmodifiableMap(result);
+  }
+
   public Map<String, String> getMergedSpanTags() {
     // DO not include runtimeId into span tags: we only want that added to the root span
     final Map<String, String> result = newHashMap(globalTags.size() + spanTags.size());
@@ -336,7 +364,7 @@ public Map<String, String> getMergedJmxTags() {
    *
    * @return A map of tag-name -> tag-value
    */
-  public Map<String, String> getRuntimeTags() {
+  private Map<String, String> getRuntimeTags() {
     final Map<String, String> result = newHashMap(2);
     result.put(RUNTIME_ID_TAG, runtimeId);
     result.put(LANGUAGE_TAG_KEY, LANGUAGE_TAG_VALUE);
@@ -636,6 +664,20 @@ private static <V extends Enum<V>> Set<V> convertStringSetToEnumSet(
     return Collections.unmodifiableSet(result);
   }
 
+  /**
+   * Returns the detected hostname. This operation is time consuming so if the usage changes and
+   * this method will be called several times then we should implement some sort of caching.
+   */
+  private String getHostname() {
+    try {
+      return InetAddress.getLocalHost().getHostName();
+    } catch (UnknownHostException e) {
+      // If we are not able to detect the hostname we do not throw an exception.
+    }
+
+    return null;
+  }
+
   // This has to be placed after all other static fields to give them a chance to initialize
   private static final Config INSTANCE = new Config();
 

dd-trace-api/src/main/java/datadog/trace/api/interceptor/MutableSpan.java

@@ -50,5 +50,16 @@ public interface MutableSpan {
 
   MutableSpan setError(boolean value);
 
+  /** @deprecated Use {@link #getLocalRootSpan()} instead. */
+  @Deprecated
   MutableSpan getRootSpan();
+
+  /**
+   * Returns the root span for current the trace fragment. In the context of distributed tracing
+   * this method returns the root span only for the fragment generated by the currently traced
+   * application.
+   *
+   * @return The root span for the current trace fragment.
+   */
+  MutableSpan getLocalRootSpan();
 }

dd-trace-api/src/test/groovy/datadog/trace/api/ConfigTest.groovy

@@ -35,6 +35,7 @@ import static datadog.trace.api.Config.SERVICE_MAPPING
 import static datadog.trace.api.Config.SERVICE_NAME
 import static datadog.trace.api.Config.SPAN_TAGS
 import static datadog.trace.api.Config.TRACE_AGENT_PORT
+import static datadog.trace.api.Config.TRACE_REPORT_HOSTNAME
 import static datadog.trace.api.Config.TRACE_ENABLED
 import static datadog.trace.api.Config.TRACE_RESOLVER_ENABLED
 import static datadog.trace.api.Config.WRITER_TYPE
@@ -56,6 +57,7 @@ class ConfigTest extends Specification {
   private static final DD_JMXFETCH_METRICS_CONFIGS_ENV = "DD_JMXFETCH_METRICS_CONFIGS"
   private static final DD_TRACE_AGENT_PORT_ENV = "DD_TRACE_AGENT_PORT"
   private static final DD_AGENT_PORT_LEGACY_ENV = "DD_AGENT_PORT"
+  private static final DD_TRACE_REPORT_HOSTNAME = "DD_TRACE_REPORT_HOSTNAME"
 
   def "verify defaults"() {
     when:
@@ -78,6 +80,7 @@ class ConfigTest extends Specification {
     config.httpClientErrorStatuses == (400..499).toSet()
     config.httpClientSplitByDomain == false
     config.partialFlushMinSpans == 1000
+    config.reportHostName == false
     config.runtimeContextFieldInjection == true
     config.propagationStylesToExtract.toList() == [Config.PropagationStyle.DATADOG]
     config.propagationStylesToInject.toList() == [Config.PropagationStyle.DATADOG]
@@ -118,6 +121,7 @@ class ConfigTest extends Specification {
     prop.setProperty(HTTP_CLIENT_ERROR_STATUSES, "111")
     prop.setProperty(HTTP_CLIENT_HOST_SPLIT_BY_DOMAIN, "true")
     prop.setProperty(PARTIAL_FLUSH_MIN_SPANS, "15")
+    prop.setProperty(TRACE_REPORT_HOSTNAME, "true")
     prop.setProperty(RUNTIME_CONTEXT_FIELD_INJECTION, "false")
     prop.setProperty(PROPAGATION_STYLE_EXTRACT, "Datadog, B3")
     prop.setProperty(PROPAGATION_STYLE_INJECT, "B3, Datadog")
@@ -148,6 +152,7 @@ class ConfigTest extends Specification {
     config.httpClientErrorStatuses == (111..111).toSet()
     config.httpClientSplitByDomain == true
     config.partialFlushMinSpans == 15
+    config.reportHostName == true
     config.runtimeContextFieldInjection == false
     config.propagationStylesToExtract.toList() == [Config.PropagationStyle.DATADOG, Config.PropagationStyle.B3]
     config.propagationStylesToInject.toList() == [Config.PropagationStyle.B3, Config.PropagationStyle.DATADOG]
@@ -179,6 +184,7 @@ class ConfigTest extends Specification {
     System.setProperty(PREFIX + HTTP_CLIENT_ERROR_STATUSES, "111")
     System.setProperty(PREFIX + HTTP_CLIENT_HOST_SPLIT_BY_DOMAIN, "true")
     System.setProperty(PREFIX + PARTIAL_FLUSH_MIN_SPANS, "25")
+    System.setProperty(PREFIX + TRACE_REPORT_HOSTNAME, "true")
     System.setProperty(PREFIX + RUNTIME_CONTEXT_FIELD_INJECTION, "false")
     System.setProperty(PREFIX + PROPAGATION_STYLE_EXTRACT, "Datadog, B3")
     System.setProperty(PREFIX + PROPAGATION_STYLE_INJECT, "B3, Datadog")
@@ -209,6 +215,7 @@ class ConfigTest extends Specification {
     config.httpClientErrorStatuses == (111..111).toSet()
     config.httpClientSplitByDomain == true
     config.partialFlushMinSpans == 25
+    config.reportHostName == true
     config.runtimeContextFieldInjection == false
     config.propagationStylesToExtract.toList() == [Config.PropagationStyle.DATADOG, Config.PropagationStyle.B3]
     config.propagationStylesToInject.toList() == [Config.PropagationStyle.B3, Config.PropagationStyle.DATADOG]
@@ -228,6 +235,7 @@ class ConfigTest extends Specification {
     environmentVariables.set(DD_PROPAGATION_STYLE_EXTRACT, "B3 Datadog")
     environmentVariables.set(DD_PROPAGATION_STYLE_INJECT, "Datadog B3")
     environmentVariables.set(DD_JMXFETCH_METRICS_CONFIGS_ENV, "some/file")
+    environmentVariables.set(DD_TRACE_REPORT_HOSTNAME, "true")
 
     when:
     def config = new Config()
@@ -239,6 +247,7 @@ class ConfigTest extends Specification {
     config.propagationStylesToExtract.toList() == [Config.PropagationStyle.B3, Config.PropagationStyle.DATADOG]
     config.propagationStylesToInject.toList() == [Config.PropagationStyle.DATADOG, Config.PropagationStyle.B3]
     config.jmxFetchMetricsConfigs == ["some/file"]
+    config.reportHostName == true
   }
 
   def "sys props override env vars"() {
@@ -649,4 +658,27 @@ class ConfigTest extends Specification {
     listString | list
     ""         | []
   }
+
+  def "verify hostname not added to root span tags by default"() {
+    setup:
+    Properties properties = new Properties()
+
+    when:
+    def config = Config.get(properties)
+
+    then:
+    !config.localRootSpanTags.containsKey('_dd.hostname')
+  }
+
+  def "verify configuration to add hostname to root span tags"() {
+    setup:
+    Properties properties = new Properties()
+    properties.setProperty(TRACE_REPORT_HOSTNAME, 'true')
+
+    when:
+    def config = Config.get(properties)
+
+    then:
+    config.localRootSpanTags.get('_dd.hostname') == InetAddress.localHost.hostName
+  }
 }

dd-trace-ot/src/main/java/datadog/opentracing/DDSpan.java

@@ -110,8 +110,16 @@ public final void finish(final long stoptimeMicros) {
     finishAndAddToTrace(TimeUnit.MICROSECONDS.toNanos(stoptimeMicros - startTimeMicro));
   }
 
+  @Override
+  public DDSpan setError(final boolean error) {
+    context.setErrorFlag(true);
+    return this;
+  }
+
   /**
-   * Check if the span is the root parent. It means that the traceId is the same as the spanId
+   * Check if the span is the root parent. It means that the traceId is the same as the spanId. In
+   * the context of distributed tracing this will return true if an only if this is the application
+   * initializing the trace.
    *
    * @return true if root, false otherwise
    */
@@ -121,13 +129,15 @@ public final boolean isRootSpan() {
   }
 
   @Override
-  public DDSpan setError(final boolean error) {
-    context.setErrorFlag(true);
-    return this;
+  @Deprecated
+  @JsonIgnore
+  public MutableSpan getRootSpan() {
+    return getLocalRootSpan();
   }
 
   @Override
-  public MutableSpan getRootSpan() {
+  @JsonIgnore
+  public MutableSpan getLocalRootSpan() {
     return context().getTrace().getRootSpan();
   }