Allow config to pull from env vars and sys props

dd-trace/src/main/java/com/datadoghq/trace/DDTraceConfig.java

@@ -0,0 +1,63 @@
+package com.datadoghq.trace;
+
+import java.util.Properties;
+
+/**
+ * Config gives priority to system properties and falls back to environment variables.
+ *
+ * <p>System properties are {@link DDTraceConfig#PREFIX}'ed. Environment variables are the same as
+ * the system property, but uppercased with '.' -> '_'.
+ */
+public class DDTraceConfig extends Properties {
+  /** Config keys bel */
+  private static final String PREFIX = "dd.";
+
+  public static final String SERVICE_NAME = "service.name";
+  public static final String WRITER_TYPE = "writer.type";
+  public static final String AGENT_HOST = "agent.host";
+  public static final String AGENT_PORT = "agent.port";
+  public static final String SAMPLER_TYPE = "sampler.type";
+  public static final String SAMPLER_RATE = "sampler.rate";
+
+  private final String serviceName = getPropOrEnv(PREFIX + SERVICE_NAME);
+  private final String writerType = getPropOrEnv(PREFIX + WRITER_TYPE);
+  private final String agentHost = getPropOrEnv(PREFIX + AGENT_HOST);
+  private final String agentPort = getPropOrEnv(PREFIX + AGENT_PORT);
+  private final String samplerType = getPropOrEnv(PREFIX + SAMPLER_TYPE);
+  private final String samplerRate = getPropOrEnv(PREFIX + SAMPLER_RATE);
+
+  public DDTraceConfig() {
+    super();
+
+    final Properties defaults = new Properties();
+    defaults.setProperty(SERVICE_NAME, DDTracer.UNASSIGNED_DEFAULT_SERVICE_NAME);
+    super.defaults = defaults;
+
+    final Properties baseValues = new Properties(defaults);
+    setIfNotNull(SERVICE_NAME, serviceName);
+    setIfNotNull(WRITER_TYPE, writerType);
+    setIfNotNull(AGENT_HOST, agentHost);
+    setIfNotNull(AGENT_PORT, agentPort);
+    setIfNotNull(SAMPLER_TYPE, samplerType);
+    setIfNotNull(SAMPLER_RATE, samplerRate);
+  }
+
+  public DDTraceConfig(final String serviceName) {
+    super();
+    put(SERVICE_NAME, serviceName);
+  }
+
+  private void setIfNotNull(final String key, final String value) {
+    if (value != null) {
+      setProperty(key, value);
+    }
+  }
+
+  private String getPropOrEnv(final String name) {
+    return System.getProperty(name, System.getenv(propToEnvName(name)));
+  }
+
+  static String propToEnvName(final String name) {
+    return name.toUpperCase().replace(".", "_");
+  }
+}

dd-trace/src/main/java/com/datadoghq/trace/DDTracer.java

@@ -3,9 +3,10 @@ package com.datadoghq.trace;
 import com.datadoghq.trace.integration.AbstractDecorator;
 import com.datadoghq.trace.propagation.Codec;
 import com.datadoghq.trace.propagation.HTTPCodec;
+import com.datadoghq.trace.resolver.DDDecoratorsFactory;
 import com.datadoghq.trace.sampling.AllSampler;
 import com.datadoghq.trace.sampling.Sampler;
-import com.datadoghq.trace.writer.LoggingWriter;
+import com.datadoghq.trace.writer.DDAgentWriter;
 import com.datadoghq.trace.writer.Writer;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import io.opentracing.ActiveSpan;
@@ -19,6 +20,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Properties;
 import java.util.Queue;
 import java.util.concurrent.ThreadLocalRandom;
 import lombok.extern.slf4j.Slf4j;
@@ -28,16 +30,16 @@ import lombok.extern.slf4j.Slf4j;
 public class DDTracer extends ThreadLocalActiveSpanSource implements io.opentracing.Tracer {
 
   public static final String UNASSIGNED_DEFAULT_SERVICE_NAME = "unnamed-java-app";
-  public static final Writer UNASSIGNED_WRITER = new LoggingWriter();
+  public static final Writer UNASSIGNED_WRITER = new DDAgentWriter();
   public static final Sampler UNASSIGNED_SAMPLER = new AllSampler();
 
   /** Writer is an charge of reporting traces and spans to the desired endpoint */
-  private final Writer writer;
+  final Writer writer;
   /** Sampler defines the sampling policy in order to reduce the number of traces for instance */
-  private final Sampler sampler;
+  final Sampler sampler;
 
   /** Default service name if none provided on the trace or span */
-  private final String defaultServiceName;
+  final String serviceName;
 
   /** Span context decorators */
   private final Map<String, List<AbstractDecorator>> spanContextDecorators = new HashMap<>();
@@ -45,9 +47,39 @@ public class DDTracer extends ThreadLocalActiveSpanSource implements io.opentrac
   private final CodecRegistry registry;
   private final Map<String, Service> services = new HashMap<>();
 
-  /** Default constructor, trace/spans are logged, no trace/span dropped */
+  /** By default, report to local agent and collect all traces. */
   public DDTracer() {
-    this(UNASSIGNED_WRITER);
+    this(new DDTraceConfig());
+  }
+
+  public DDTracer(final String serviceName) {
+    this(new DDTraceConfig(serviceName));
+  }
+
+  public DDTracer(final Properties config) {
+    this(
+        config.getProperty(DDTraceConfig.SERVICE_NAME),
+        Writer.Builder.forConfig(config),
+        Sampler.Builder.forConfig(config));
+    log.debug("Using config: {}", config);
+
+    // Create decorators from resource files
+    final List<AbstractDecorator> decorators = DDDecoratorsFactory.createFromResources();
+    for (final AbstractDecorator decorator : decorators) {
+      log.debug("Loading decorator: {}", decorator.getClass().getSimpleName());
+      addDecorator(decorator);
+    }
+  }
+
+  public DDTracer(final String serviceName, final Writer writer, final Sampler sampler) {
+    this.serviceName = serviceName;
+    this.writer = writer;
+    this.writer.start();
+    this.sampler = sampler;
+    registry = new CodecRegistry();
+    registry.register(Format.Builtin.HTTP_HEADERS, new HTTPCodec());
+    registry.register(Format.Builtin.TEXT_MAP, new HTTPCodec());
+    log.info("New instance: {}", this);
   }
 
   public DDTracer(final Writer writer) {
@@ -58,21 +90,6 @@ public class DDTracer extends ThreadLocalActiveSpanSource implements io.opentrac
     this(UNASSIGNED_DEFAULT_SERVICE_NAME, writer, sampler);
   }
 
-  public DDTracer(final String defaultServiceName, final Writer writer, final Sampler sampler) {
-    this.defaultServiceName = defaultServiceName;
-    this.writer = writer;
-    this.writer.start();
-    this.sampler = sampler;
-    registry = new CodecRegistry();
-    registry.register(Format.Builtin.HTTP_HEADERS, new HTTPCodec());
-    registry.register(Format.Builtin.TEXT_MAP, new HTTPCodec());
-    log.debug(
-        "New tracer instance, default-service={}, writer={}, sampler={}",
-        defaultServiceName,
-        writer.getClass().getSimpleName(),
-        sampler.getClass().getSimpleName());
-  }
-
   /**
    * Returns the list of span context decorators
    *
@@ -147,7 +164,15 @@ public class DDTracer extends ThreadLocalActiveSpanSource implements io.opentrac
 
   @Override
   public String toString() {
-    return "DDTracer{" + "writer=" + writer + ", sampler=" + sampler + '}';
+    return "DDTracer-"
+        + Integer.toHexString(hashCode())
+        + "{ service-name="
+        + serviceName
+        + ", writer="
+        + writer
+        + ", sampler="
+        + sampler
+        + '}';
   }
 
   /**
@@ -368,7 +393,7 @@ public class DDTracer extends ThreadLocalActiveSpanSource implements io.opentrac
       }
 
       if (serviceName == null) {
-        serviceName = defaultServiceName;
+        serviceName = DDTracer.this.serviceName;
       }
 
       final String operationName =

dd-trace/src/main/java/com/datadoghq/trace/resolver/DDTracerFactory.java

@@ -33,7 +33,7 @@ public class DDTracerFactory {
    * @param config
    * @return the corresponding tracer
    */
-  public static DDTracer create(final TracerConfig config) {
+  static DDTracer create(final TracerConfig config) {
     final String defaultServiceName =
         config.getDefaultServiceName() != null
             ? config.getDefaultServiceName()
@@ -88,11 +88,15 @@ public class DDTracerFactory {
     return new DDTracer(defaultServiceName, writer, sampler);
   }
 
+  @Deprecated
   public static DDTracer createFromConfigurationFile() {
     final TracerConfig tracerConfig =
         FactoryUtils.loadConfigFromFilePropertyOrResource(
             SYSTEM_PROPERTY_CONFIG_PATH, CONFIG_PATH, TracerConfig.class);
 
+    log.warn("DDTracerFactory is deprecated and will be removed in the next release.");
+    log.warn("Use the constructor on DDTrace directly and env vars/sys props for config.");
+
     DDTracer tracer = null;
     log.trace("Tracer configuration: \n{}", tracerConfig);
     if (tracerConfig == null) {

dd-trace/src/main/java/com/datadoghq/trace/resolver/DDTracerResolver.java

@@ -29,11 +29,16 @@ public class DDTracerResolver extends TracerResolver {
   protected Tracer resolve() {
     log.info("Creating the Datadog Tracer from the resolver");
 
-    // Find a resource file named dd-trace.yml
-    DDTracer tracer = null;
-    // Create tracer from resource files
-    tracer = DDTracerFactory.createFromConfigurationFile();
+    final TracerConfig tracerConfig =
+        FactoryUtils.loadConfigFromFilePropertyOrResource(
+            DDTracerFactory.SYSTEM_PROPERTY_CONFIG_PATH,
+            DDTracerFactory.CONFIG_PATH,
+            TracerConfig.class);
 
-    return tracer;
+    if (tracerConfig != null) {
+      return DDTracerFactory.createFromConfigurationFile();
+    } else {
+      return new DDTracer();
+    }
   }
 }

dd-trace/src/main/java/com/datadoghq/trace/sampling/RateSampler.java

@@ -17,6 +17,10 @@ public class RateSampler extends AbstractSampler {
   /** The sample rate used */
   private final double sampleRate;
 
+  public RateSampler(final String sampleRate) {
+    this(sampleRate == null ? 1 : Double.valueOf(sampleRate));
+  }
+
   /**
    * Build an instance of the sampler. The Sample rate is fixed for each instance.
    *
@@ -45,4 +49,9 @@ public class RateSampler extends AbstractSampler {
   public double getSampleRate() {
     return this.sampleRate;
   }
+
+  @Override
+  public String toString() {
+    return "RateSampler { sampleRate=" + sampleRate + " }";
+  }
 }

dd-trace/src/main/java/com/datadoghq/trace/sampling/Sampler.java

@@ -1,9 +1,14 @@
 package com.datadoghq.trace.sampling;
 
 import com.datadoghq.trace.DDBaseSpan;
+import com.datadoghq.trace.DDTraceConfig;
+import com.datadoghq.trace.DDTracer;
+import java.util.Properties;
 
 /** Main interface to sample a collection of traces. */
 public interface Sampler {
+  static final String ALL_SAMPLER_TYPE = AllSampler.class.getSimpleName();
+  static final String RATE_SAMPLER_TYPE = RateSampler.class.getSimpleName();
 
   /**
    * Sample a collection of traces based on the parent span
@@ -12,4 +17,26 @@ public interface Sampler {
    * @return true when the trace/spans has to be reported/written
    */
   boolean sample(DDBaseSpan<?> span);
+
+  final class Builder {
+    public static Sampler forConfig(final Properties config) {
+      final Sampler sampler;
+
+      if (config != null) {
+        final String configuredType = config.getProperty(DDTraceConfig.SAMPLER_TYPE);
+        if (RATE_SAMPLER_TYPE.equals(configuredType)) {
+          sampler = new RateSampler(config.getProperty(DDTraceConfig.SAMPLER_RATE));
+        } else if (ALL_SAMPLER_TYPE.equals(configuredType)) {
+          sampler = new AllSampler();
+        } else {
+          sampler = DDTracer.UNASSIGNED_SAMPLER;
+        }
+      } else {
+        sampler = DDTracer.UNASSIGNED_SAMPLER;
+      }
+      return sampler;
+    }
+
+    private Builder() {}
+  }
 }

dd-trace/src/main/java/com/datadoghq/trace/writer/DDAgentWriter.java

@@ -140,6 +140,11 @@ public class DDAgentWriter implements Writer {
     }
   }
 
+  @Override
+  public String toString() {
+    return "DDAgentWriter { api=" + api + " }";
+  }
+
   /** Infinite tasks blocking until some spans come in the blocking queue. */
   class TracesSendingTask implements Runnable {
 

dd-trace/src/main/java/com/datadoghq/trace/writer/DDApi.java

@@ -126,4 +126,9 @@ public class DDApi {
     httpCon.setRequestProperty("Datadog-Meta-Tracer-Version", DDTraceInfo.VERSION);
     return httpCon;
   }
+
+  @Override
+  public String toString() {
+    return "DDApi { tracesEndpoint=" + tracesEndpoint + " }";
+  }
 }

dd-trace/src/main/java/com/datadoghq/trace/writer/Writer.java

@@ -1,12 +1,17 @@
 package com.datadoghq.trace.writer;
 
 import com.datadoghq.trace.DDBaseSpan;
+import com.datadoghq.trace.DDTraceConfig;
+import com.datadoghq.trace.DDTracer;
 import com.datadoghq.trace.Service;
 import java.util.List;
 import java.util.Map;
+import java.util.Properties;
 
 /** A writer is responsible to send collected spans to some place */
 public interface Writer {
+  static final String DD_AGENT_WRITER_TYPE = DDAgentWriter.class.getSimpleName();
+  static final String LOGGING_WRITER_TYPE = LoggingWriter.class.getSimpleName();
 
   /**
    * Write a trace represented by the entire list of all the finished spans
@@ -30,4 +35,31 @@ public interface Writer {
    * connections and tasks
    */
   void close();
+
+  final class Builder {
+    public static Writer forConfig(final Properties config) {
+      final Writer writer;
+
+      if (config != null) {
+        final String configuredType = config.getProperty(DDTraceConfig.WRITER_TYPE);
+        if (DD_AGENT_WRITER_TYPE.equals(configuredType)) {
+          writer =
+              new DDAgentWriter(
+                  new DDApi(
+                      config.getProperty(DDTraceConfig.AGENT_HOST),
+                      Integer.parseInt(config.getProperty(DDTraceConfig.AGENT_PORT))));
+        } else if (LOGGING_WRITER_TYPE.equals(configuredType)) {
+          writer = new LoggingWriter();
+        } else {
+          writer = DDTracer.UNASSIGNED_WRITER;
+        }
+      } else {
+        writer = DDTracer.UNASSIGNED_WRITER;
+      }
+
+      return writer;
+    }
+
+    private Builder() {}
+  }
 }

dd-trace/src/test/groovy/com/datadoghq/trace/DDTraceConfigTest.groovy

@@ -0,0 +1,145 @@
+package com.datadoghq.trace
+
+import com.datadoghq.trace.sampling.AllSampler
+import com.datadoghq.trace.sampling.RateSampler
+import com.datadoghq.trace.writer.DDAgentWriter
+import com.datadoghq.trace.writer.ListWriter
+import com.datadoghq.trace.writer.LoggingWriter
+import spock.lang.Specification
+
+import java.lang.reflect.Field
+import java.lang.reflect.Modifier
+
+import static com.datadoghq.trace.DDTraceConfig.*
+
+class DDTraceConfigTest extends Specification {
+  static originalEnvMap
+  static overrideEnvMap = new HashMap<String, String>()
+
+  def setupSpec() {
+    def envMapField = ProcessEnvironment.getDeclaredField("theUnmodifiableEnvironment")
+    envMapField.setAccessible(true)
+
+    Field modifiersField = Field.getDeclaredField("modifiers")
+    modifiersField.setAccessible(true)
+    modifiersField.setInt(envMapField, envMapField.getModifiers() & ~Modifier.FINAL)
+
+    originalEnvMap = envMapField.get(null)
+    overrideEnvMap.putAll(originalEnvMap)
+    envMapField.set(null, overrideEnvMap)
+  }
+
+  def cleanupSpec() {
+    def envMapField = ProcessEnvironment.getDeclaredField("theUnmodifiableEnvironment")
+    envMapField.setAccessible(true)
+
+    Field modifiersField = Field.getDeclaredField("modifiers")
+    modifiersField.setAccessible(true)
+    modifiersField.setInt(envMapField, envMapField.getModifiers() & ~Modifier.FINAL)
+
+    originalEnvMap = envMapField.get(null)
+    envMapField.set(null, originalEnvMap)
+  }
+
+  def setup() {
+    overrideEnvMap.clear()
+    overrideEnvMap.putAll(originalEnvMap)
+
+    System.clearProperty(PREFIX + SERVICE_NAME)
+    System.clearProperty(PREFIX + WRITER_TYPE)
+    System.clearProperty(PREFIX + AGENT_HOST)
+    System.clearProperty(PREFIX + AGENT_PORT)
+    System.clearProperty(PREFIX + SAMPLER_TYPE)
+    System.clearProperty(PREFIX + SAMPLER_RATE)
+  }
+
+  def "verify env override"() {
+    setup:
+    overrideEnvMap.put("SOME_RANDOM_ENTRY", "asdf")
+
+    expect:
+    System.getenv("SOME_RANDOM_ENTRY") == "asdf"
+  }
+
+  def "verify defaults"() {
+    when:
+    def config = new DDTraceConfig()
+
+    then:
+    config.getProperty(SERVICE_NAME) == "unnamed-java-app"
+    config.getProperty(WRITER_TYPE) == null
+    config.getProperty(AGENT_HOST) == null
+    config.getProperty(AGENT_PORT) == null
+    config.getProperty(SAMPLER_TYPE) == null
+    config.getProperty(SAMPLER_RATE) == null
+
+    when:
+    config = new DDTraceConfig("A different service name")
+
+    then:
+    config.getProperty(SERVICE_NAME) == "A different service name"
+    config.getProperty(WRITER_TYPE) == null
+    config.getProperty(AGENT_HOST) == null
+    config.getProperty(AGENT_PORT) == null
+    config.getProperty(SAMPLER_TYPE) == null
+    config.getProperty(SAMPLER_RATE) == null
+  }
+
+  def "specify overrides via system properties"() {
+    when:
+    System.setProperty(PREFIX + SERVICE_NAME, "something else")
+    System.setProperty(PREFIX + WRITER_TYPE, LoggingWriter.simpleName)
+    System.setProperty(PREFIX + SAMPLER_TYPE, RateSampler.simpleName)
+    System.setProperty(PREFIX + SAMPLER_RATE, ".5")
+    def tracer = new DDTracer()
+
+    then:
+    tracer.serviceName == "something else"
+    tracer.writer instanceof LoggingWriter
+    tracer.sampler.toString() == "RateSampler { sampleRate=0.5 }"
+  }
+
+  def "specify overrides via env vars"() {
+    when:
+    overrideEnvMap.put(propToEnvName(PREFIX + SERVICE_NAME), "still something else")
+    overrideEnvMap.put(propToEnvName(PREFIX + WRITER_TYPE), LoggingWriter.simpleName)
+    overrideEnvMap.put(propToEnvName(PREFIX + SAMPLER_TYPE), AllSampler.simpleName)
+    def tracer = new DDTracer()
+
+    then:
+    tracer.serviceName == "still something else"
+    tracer.writer instanceof LoggingWriter
+    tracer.sampler instanceof AllSampler
+  }
+
+  def "sys props override env vars"() {
+    when:
+    overrideEnvMap.put(propToEnvName(PREFIX + SERVICE_NAME), "still something else")
+    overrideEnvMap.put(propToEnvName(PREFIX + WRITER_TYPE), ListWriter.simpleName)
+    overrideEnvMap.put(propToEnvName(PREFIX + SAMPLER_TYPE), AllSampler.simpleName)
+
+    System.setProperty(PREFIX + SERVICE_NAME, "what we actually want")
+    System.setProperty(PREFIX + WRITER_TYPE, DDAgentWriter.simpleName)
+    System.setProperty(PREFIX + AGENT_HOST, "somewhere")
+    System.setProperty(PREFIX + AGENT_PORT, "9999")
+    System.setProperty(PREFIX + SAMPLER_TYPE, RateSampler.simpleName)
+    System.setProperty(PREFIX + SAMPLER_RATE, ".9")
+
+    def tracer = new DDTracer()
+
+    then:
+    tracer.serviceName == "what we actually want"
+    tracer.writer.toString() == "DDAgentWriter { api=DDApi { tracesEndpoint=http://somewhere:9999/v0.3/traces } }"
+    tracer.sampler.toString() == "RateSampler { sampleRate=0.9 }"
+  }
+
+  def "verify defaults on tracer"() {
+    when:
+    def tracer = new DDTracer()
+
+    then:
+    tracer.serviceName == "unnamed-java-app"
+    tracer.sampler instanceof AllSampler
+    tracer.writer.toString() == "DDAgentWriter { api=DDApi { tracesEndpoint=http://localhost:8126/v0.3/traces } }"
+  }
+}