[example] add Spark framework example (#60)

* [example] add Spark framework example
* [example] formatting

dd-trace-examples/rest-spark/docker-compose.yml

@@ -0,0 +1,12 @@
+mongo:
+    image: mongo:3.2
+    ports:
+        - "127.0.0.1:27017:27017"
+
+ddagent:
+    image: datadog/docker-dd-agent
+    environment:
+        - DD_BIND_HOST=0.0.0.0
+        - DD_API_KEY
+    ports:
+        - "127.0.0.1:8126:8126"

dd-trace-examples/rest-spark/rest-spark.gradle

@@ -0,0 +1,19 @@
+apply from: "${rootDir}/gradle/java.gradle"
+apply from: "${rootDir}/gradle/jacoco.gradle"
+
+version = 'demo'
+description = 'rest-spark'
+
+sourceCompatibility = 1.8
+targetCompatibility = 1.8
+
+dependencies {
+
+//  compile fileTree(dir: 'libs', include: ['*.jar'])
+  compile project(':dd-trace')
+  compile 'com.sparkjava:spark-core:2.6.0'
+  compile 'org.mongodb:mongodb-driver:3.4.2'
+  compile 'io.opentracing:opentracing-api:0.30.0'
+  compile 'io.opentracing:opentracing-util:0.30.0'
+  compile 'io.opentracing.contrib:opentracing-mongo-driver:0.0.2'
+}

dd-trace-examples/rest-spark/src/main/java/Hello.java

@@ -0,0 +1,51 @@
+import static spark.Spark.*;
+
+import com.datadoghq.trace.resolver.DDTracerFactory;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoDatabase;
+import io.opentracing.ActiveSpan;
+import io.opentracing.Tracer;
+import java.util.Arrays;
+import org.bson.Document;
+
+public class Hello {
+  private static MongoDatabase mDatabase;
+  private static Tracer mTracer;
+
+  public static void main(String[] args) {
+    // Init the tracer from the configuration file
+    mTracer = DDTracerFactory.createFromConfigurationFile();
+    io.opentracing.util.GlobalTracer.register(mTracer);
+
+    // initialize the Mongo database
+    mDatabase = MongoDriver.getDatabase("rest_spark");
+
+    // our routes
+    get("/healthz", (req, res) -> "OK!");
+    get(
+        "/key/:id",
+        (req, res) -> {
+          try (ActiveSpan activeSpan = mTracer.buildSpan("spark.request").startActive()) {
+            activeSpan.setTag("http.url", req.url());
+
+            String id = req.params(":id");
+
+            // create a collection
+            Document doc =
+                new Document("name", "MongoDB")
+                    .append("type", "database")
+                    .append("identifier", id)
+                    .append("versions", Arrays.asList("v3.2", "v3.0", "v2.6"))
+                    .append("info", new Document("x", 203).append("y", 102));
+
+            MongoCollection<Document> collection = mDatabase.getCollection("calls");
+            collection.insertOne(doc);
+
+            // write the count somewhere
+            System.out.println(collection.count());
+
+            return "Stored!";
+          }
+        });
+  }
+}

dd-trace-examples/rest-spark/src/main/java/MongoDriver.java

@@ -0,0 +1,15 @@
+import com.mongodb.MongoClient;
+import com.mongodb.MongoClientURI;
+import com.mongodb.client.MongoDatabase;
+import io.opentracing.Tracer;
+import io.opentracing.contrib.mongo.TracingMongoClient;
+
+public class MongoDriver {
+
+  public static MongoDatabase getDatabase(String dbName) {
+    Tracer tracer = io.opentracing.util.GlobalTracer.get();
+    MongoClientURI connectionString = new MongoClientURI("mongodb://localhost:27017");
+    MongoClient mongoClient = new TracingMongoClient(tracer, connectionString);
+    return mongoClient.getDatabase(dbName);
+  }
+}

dd-trace-examples/rest-spark/src/main/resources/dd-trace.yaml

@@ -0,0 +1,34 @@
+# Main service name for the app
+defaultServiceName: rest-spark
+
+# The writer to use.
+# Could be: LoggingWritter or DDAgentWriter (default)
+writer:
+  # LoggingWriter: Spans are logged using the application configuration
+  # DDAgentWriter: Spans are forwarding to a Datadog trace Agent
+  #  - Param 'host': the hostname where the DD trace Agent is running (default: localhost)
+  #  - Param 'port': the port to reach the DD trace Agent (default: 8126)
+  type: DDAgentWriter
+  host: localhost
+  port: 8126
+
+# The sampler to use.
+# Could be: AllSampler (default) or RateSampler
+sampler:
+  # AllSampler: all spans are reported to the writer
+  # RateSample: only a portion of spans are reported to the writer
+  #  - Param 'rate': the portion of spans to keep
+  type: AllSampler
+  # Skip some traces if the root span tag values matches some regexp patterns
+  # skipTagsPatterns: {"http.url": ".*/demo/add.*"}
+
+# Enable custom tracing (Custom annotations for now)
+# enableCustomAnnotationTracingOver: ["io","org","com"]
+
+# Disable some instrumentations
+# disabledInstrumentations: ["opentracing-apache-httpclient", "opentracing-mongo-driver", "opentracing-web-servlet-filter"]
+
+decorators:
+  - type: DBComponent
+    matchingValue: java-mongo
+    setValue: mongo-spark

settings.gradle

@@ -6,6 +6,7 @@ include ':dd-java-agent-ittests'
 include ':dd-trace-examples:async-tracing'
 include ':dd-trace-examples:dropwizard-mongo-client'
 include ':dd-trace-examples:spring-boot-jdbc'
+include ':dd-trace-examples:rest-spark'
 include ':dd-trace-examples'
 include ':dd-trace-annotations'