Tracing Java Applications

Compatibility requirements

The Java Tracing Library supports all JVMs on all platforms version 7 and higher. To utilize tracing with the Continuous Profiler, OpenJDK 11+, Oracle Java 11+, OpenJDK 8 for most vendors (version 8u262+) and Zulu Java 8+ (minor version 1.8.0_212+) are supported. Starting in version 8u272+, all vendors will be supported for the Profiler.

All JVM-based languages, such as Scala (versions 2.10.x - 2.13.x), Groovy, Kotlin, and Clojure are supported in the Java tracer and profiler. For a full list of supported libraries, visit the Compatibility Requirements page.

When you set up tracing, you’re also setting up Continuous Profiler, and you need only enable Profiler to start receiving profiling data from your app.

Installation and getting started

Follow the Quickstart instructions within the Datadog app for the best experience, including:

  • Step-by-step instructions scoped to your deployment configuration (hosts, Docker, Kubernetes, or Amazon ECS).
  • Dynamically set service, env and version tags.
  • Enable the Continuous Profiler, ingesting 100% of traces, and Trace ID injection into logs during setup.

Java installation

Otherwise, to begin tracing your applications:

  1. Download dd-java-agent.jar that contains the latest Agent class files:

    wget -O dd-java-agent.jar https://dtdg.co/latest-java-tracer

    To access a specific version of the tracer, visit Datadog’s Maven repository.

  2. To run your app from an IDE, Maven or Gradle application script, or java -jar command, with continuous profiler, deployment tracking, logs injection (if you are sending logs to Datadog), and trace volume control, add the -javaagent JVM argument and the following configuration options, as applicable:

    java -javaagent:/path/to/dd-java-agent.jar -Ddd.profiling.enabled=true -XX:FlightRecorderOptions=stackdepth=256 -Ddd.logs.injection=true -Ddd.trace.sample.rate=1 -Ddd.service=my-app -Ddd.env=staging -jar path/to/your/app.jar -Ddd.version=1.0

    Note: Enabling profiling may have an impact on your bill depending on your APM bundle. See the pricing page for more information.

Environment VariableSystem PropertyDescription
DD_ENVdd.envYour application environment (production, staging, etc.)
DD_SERVICEdd.serviceThe name of a set of processes that do the same job. Used for grouping stats for your application.
DD_VERSIONdd.versionYour application version (for example, 2.5, 202003181415, 1.3-alpha, etc.)
DD_PROFILING_ENABLEDdd.profiling.enabledEnable the Continous Profiler
DD_LOGS_INJECTIONdd.logs.injectionEnable automatic MDC key injection for Datadog trace and span IDs. See Advanced Usage for details.
DD_TRACE_SAMPLE_RATEdd.trace.sample.rateEnable trace volume control

Additional configuration options are described below.

  1. Ensure the Datadog Agent is configured for APM and reachable from your application from the environment specific instructions below.

Configure the Datadog Agent for APM

Install and configure the Datadog Agent to receive traces from your instrumented application. By default the Datadog Agent is enabled in your datadog.yaml file under apm_config with enabled: true and listens for trace data at http://localhost:8126. For containerized environments, follow the links below to enable trace collection within the Datadog Agent.

    1. Set apm_non_local_traffic: true in the apm_config section of your main datadog.yaml configuration file.

    2. See the specific setup instructions to ensure that the Agent is configured to receive traces in a containerized environment:

    Docker
    Kubernetes
    Amazon ECS
    ECS Fargate

    1. After the application is instrumented, the trace client attempts to send traces to the Unix domain socket /var/run/datadog/apm.socket by default. If the socket does not exist, traces are sent to http://localhost:8126.

      If a different socket, host, or port is required, use the DD_TRACE_AGENT_URL environment variable. Some examples follow:

      DD_TRACE_AGENT_URL=http://custom-hostname:1234
DD_TRACE_AGENT_URL=unix:///var/run/datadog/apm.socket

      java -javaagent:<DD-JAVA-AGENT-PATH>.jar -jar <YOUR_APPLICATION_PATH>.jar

      You can also use system properties:

      java -javaagent:<DD-JAVA-AGENT-PATH>.jar \
    -Ddd.trace.agent.url=$DD_TRACE_AGENT_URL \
    -jar <YOUR_APPLICATION_PATH>.jar

      Similarly, the trace client attempts to send stats to the /var/run/datadog/dsd.socket Unix domain socket. If the socket does not exist then stats are sent to http://localhost:8125.

    1. Set DD_SITE in the Datadog Agent to to ensure the Agent sends data to the right Datadog location.

    To set up Datadog APM in AWS Lambda, see the Tracing Serverless Functions documentation.

    Tracing is available for a number of other environments, such as Heroku, Cloud Foundry, AWS Elastic Beanstalk, and Azure App Service.

    For other environments, please refer to the Integrations documentation for that environment and contact support if you are encountering any setup issues.

    Add the Java Tracer to the JVM

    Use the documentation for your application server to figure out the right way to pass in -javaagent and other JVM arguments. Here are instructions for some commonly used frameworks:

      If your app is called my_app.jar, create a my_app.conf, containing:

      JAVA_OPTS=-javaagent:/path/to/dd-java-agent.jar

      For more information, see the Spring Boot documentation.

      Open your Tomcat startup script file, for example setenv.sh on Linux, and add:

      CATALINA_OPTS="$CATALINA_OPTS -javaagent:/path/to/dd-java-agent.jar"

      Or on Windows, setenv.bat:

      set CATALINA_OPTS=%CATALINA_OPTS% -javaagent:"c:\path\to\dd-java-agent.jar"

      If a setenv file does not exist, create it in the ./bin directory of the Tomcat project folder.

      • In standalone mode:

        Add the following line to the end of standalone.conf:

      JAVA_OPTS="$JAVA_OPTS -javaagent:/path/to/dd-java-agent.jar"
      • In standalone mode and on Windows, add the following line to the end of standalone.conf.bat:
      set "JAVA_OPTS=%JAVA_OPTS% -javaagent:X:/path/to/dd-java-agent.jar"

      • In domain mode:

        Add the following line in the file domain.xml, under the tag server-groups.server-group.jvm.jvm-options:

      <option value="-javaagent:/path/to/dd-java-agent.jar"/>

      For more details, see the JBoss documentation.

      If you use jetty.sh to start Jetty as a service, edit it to add:

      JAVA_OPTIONS="${JAVA_OPTIONS} -javaagent:/path/to/dd-java-agent.jar"

      If you use start.ini to start Jetty, add the following line (under --exec, or add --exec line if it isn’t there yet):

      -javaagent:/path/to/dd-java-agent.jar

      In the administrative console:

      1. Select Servers. Under Server Type, select WebSphere application servers and select your server.
      2. Select Java and Process Management > Process Definition.
      3. In the Additional Properties section, click Java Virtual Machine.
      4. In the Generic JVM arguments text field, enter:
      -javaagent:/path/to/dd-java-agent.jar

      For additional details and options, see the WebSphere docs.

      Note

      • If you’re adding the -javaagent argument to your java -jar command, it needs to be added before the -jar argument, that is as a JVM option, not as an application argument. For example:

        java -javaagent:/path/to/dd-java-agent.jar -jar my_app.jar

        For more information, see the Oracle documentation.

      • Never add dd-java-agent to your classpath. It can cause unexpected behavior.

      Automatic instrumentation

      Automatic instrumentation for Java uses the java-agent instrumentation capabilities provided by the JVM. When a java-agent is registered, it has the ability to modify class files at load time.

      Instrumentation may come from auto-instrumentation, the OpenTracing api, or a mixture of both. Instrumentation generally captures the following info:

      • Timing duration is captured using the JVM’s nanotime clock unless a timestamp is provided from the OpenTracing API
      • Key/value tag pairs
      • Errors and stacktraces which are unhandled by the application
      • A total count of traces (requests) flowing through the system

      Configuration

      All configuration options below have system property and environment variable equivalents. If the same key type is set for both, the system property configuration takes priority. System properties can be set as JVM flags.

      Note: When using the Java tracer’s system properties, make sure that they are listed before -jar so they get read in as JVM options.

      dd.service
      Environment Variable: DD_SERVICE
      Default: unnamed-java-app
      The name of a set of processes that do the same job. Used for grouping stats for your application. Available for versions 0.50.0+.
      dd.tags
      Environment Variable: DD_TAGS
      Default: null
      Example: layer:api,team:intake
      A list of default tags to be added to every span, profile, and JMX metric. If DD_ENV or DD_VERSION is used, it overrides any env or version tag defined in DD_TAGS. Available for versions 0.50.0+.
      dd.env
      Environment Variable: DD_ENV
      Default: none
      Your application environment (for example, production, staging). Available for versions 0.48+.
      dd.version
      Environment Variable: DD_VERSION
      Default: null
      Your application version (for example, 2.5, 202003181415, 1.3-alpha). Available for versions 0.48+.
      dd.logs.injection
      Environment Variable: DD_LOGS_INJECTION
      Default: true
      Enabled automatic MDC key injection for Datadog trace and span IDs. See Advanced Usage for details.
      dd.trace.config
      Environment Variable: DD_TRACE_CONFIG
      Default: null
      Optional path to a file where configuration properties are provided one per each line. For instance, the file path can be provided as via -Ddd.trace.config=<FILE_PATH>.properties, with setting the service name in the file with dd.service=<SERVICE_NAME>
      dd.service.mapping
      Environment Variable: DD_SERVICE_MAPPING
      Default: null
      Example: mysql:my-mysql-service-name-db, postgres:my-postgres-service-name-db
      Dynamically rename services via configuration. Useful for making databases have distinct names across different services.
      dd.writer.type
      Environment Variable: DD_WRITER_TYPE
      Default: DDAgentWriter
      Default value sends traces to the Agent. Configuring with LoggingWriter instead writes traces out to the console.
      dd.agent.host
      Environment Variable: DD_AGENT_HOST
      Default: localhost
      Hostname for where to send traces to. If using a containerized environment, configure this to be the host IP. See Tracing Docker Applications for more details.
      dd.trace.agent.port
      Environment Variable: DD_TRACE_AGENT_PORT
      Default: 8126
      Port number the Agent is listening on for configured host.
      dd.trace.agent.unix.domain.socket
      Environment Variable: DD_TRACE_AGENT_UNIX_DOMAIN_SOCKET
      Default: null
      This can be used to direct trace traffic to a proxy, to later be sent to a remote Datadog Agent.
      dd.trace.agent.url
      Environment Variable: DD_TRACE_AGENT_URL
      Default: null
      The URL to send traces to. This can start with http:// to connect using HTTP or with unix:// to use a Unix Domain Socket. When set this takes precedence over DD_AGENT_HOST and DD_TRACE_AGENT_PORT. Available for versions 0.65+.
      dd.trace.agent.timeout
      Environment Variable: DD_TRACE_AGENT_TIMEOUT
      Default: 10
      Timeout in seconds for network interactions with the Datadog Agent.
      dd.trace.header.tags
      Environment Variable: DD_TRACE_HEADER_TAGS
      Default: null
      Example: CASE-insensitive-Header:my-tag-name,User-ID:userId,My-Header-And-Tag-Name
      Accepts a map of case-insensitive header keys to tag names and automatically applies matching header values as tags on traces. Also accepts entries without a specified tag name that are automatically mapped to tags of the form http.request.headers.<header-name> and http.response.headers.<header-name> respectively.

      Prior to version 0.96.0 this setting only applied to request header tags. To change back to the old behavior, add the setting -Ddd.trace.header.tags.legacy.parsing.enabled=true or the environment variable DD_TRACE_HEADER_TAGS_LEGACY_PARSING_ENABLED=true.
      dd.trace.request_header.tags
      Environment Variable: DD_TRACE_REQUEST_HEADER_TAGS
      Default: null
      Example: CASE-insensitive-Header:my-tag-name,User-ID:userId,My-Header-And-Tag-Name
      Accepts a map of case-insensitive header keys to tag names and automatically applies matching request header values as tags on traces. Also accepts entries without a specified tag name that are automatically mapped to tags of the form http.request.headers.<header-name>.
      Available since version 0.96.0.
      dd.trace.response_header.tags
      Environment Variable: DD_TRACE_RESPONSE_HEADER_TAGS
      Default: null
      Example: CASE-insensitive-Header:my-tag-name,User-ID:userId,My-Header-And-Tag-Name
      Accepts a map of case-insensitive header keys to tag names and automatically applies matching response header values as tags on traces. Also accepts entries without a specified tag name that are automatically mapped to tags of the form http.response.headers.<header-name>.
      Available since version 0.96.0.
      dd.trace.annotations
      Environment Variable: DD_TRACE_ANNOTATIONS
      Default: (listed here)
      Example: com.some.Trace;io.other.Trace
      A list of method annotations to treat as @Trace.
      dd.trace.methods
      Environment Variable: DD_TRACE_METHODS
      Default: null
      Example: package.ClassName[method1,method2,...];AnonymousClass$1[call];package.ClassName[*]
      List of class/interface and methods to trace. Similar to adding @Trace, but without changing code. Note: The wildcard method support ([*]) does not accommodate constructors, getters, setters, synthetic, toString, equals, hashcode, or finalizer method calls
      dd.trace.classes.exclude
      Environment Variable: DD_TRACE_CLASSES_EXCLUDE
      Default: null
      Example: package.ClassName,package.ClassName$Nested,package.Foo*,package.other.*
      A list of fully qualified classes (that may end with a wildcard to denote a prefix) which will be ignored (not modified) by the tracer. Must use the jvm internal representation for names (eg package.ClassName$Nested and not package.ClassName.Nested)
      dd.trace.partial.flush.min.spans
      Environment Variable: DD_TRACE_PARTIAL_FLUSH_MIN_SPANS
      Default: 1000
      Set a number of partial spans to flush on. Useful to reduce memory overhead when dealing with heavy traffic or long running traces.
      dd.trace.split-by-tags
      Environment Variable: DD_TRACE_SPLIT_BY_TAGS
      Default: null
      Example: aws.service
      Used to rename the service name associated with spans to be identified with the corresponding span tag
      dd.trace.db.client.split-by-instance
      Environment Variable: DD_TRACE_DB_CLIENT_SPLIT_BY_INSTANCE
      Default: false
      When set to true db spans get assigned the instance name as the service name
      dd.trace.health.metrics.enabled
      Environment Variable: DD_TRACE_HEALTH_METRICS_ENABLED
      Default: false
      When set to true sends tracer health metrics
      dd.trace.health.metrics.statsd.host
      Environment Variable: DD_TRACE_HEALTH_METRICS_STATSD_HOST
      Default: Same as dd.jmxfetch.statsd.host
      Statsd host to send health metrics to
      dd.trace.health.metrics.statsd.port
      Environment Variable: DD_TRACE_HEALTH_METRICS_STATSD_PORT
      Default: Same as dd.jmxfetch.statsd.port
      Statsd port to send health metrics to
      dd.http.client.tag.query-string
      Environment Variable: DD_HTTP_CLIENT_TAG_QUERY_STRING
      Default: false
      When set to true query string parameters and fragment get added to web client spans
      dd.http.client.error.statuses
      Environment Variable: DD_HTTP_CLIENT_ERROR_STATUSES
      Default: 400-499
      A range of errors can be accepted. By default 4xx errors are reported as errors for http clients. This configuration overrides that. Ex. dd.http.client.error.statuses=400-403,405,410-499
      dd.http.server.error.statuses
      Environment Variable: DD_HTTP_SERVER_ERROR_STATUSES
      Default: 500-599
      A range of errors can be accepted. By default 5xx status codes are reported as errors for http servers. This configuration overrides that. Ex. dd.http.server.error.statuses=500,502-599
      dd.http.server.tag.query-string
      Environment Variable: DD_HTTP_SERVER_TAG_QUERY_STRING
      Default: false
      When set to true query string parameters and fragment get added to web server spans
      dd.trace.enabled
      Environment Variable: DD_TRACE_ENABLED
      Default: true
      When false tracing agent is disabled.
      dd.jmxfetch.enabled
      Environment Variable: DD_JMXFETCH_ENABLED
      Default: true
      Enable collection of JMX metrics by Java Tracing Agent.
      dd.jmxfetch.config.dir
      Environment Variable: DD_JMXFETCH_CONFIG_DIR
      Default: null
      Example: /path/to/directory/etc/conf.d
      Additional configuration directory for JMX metrics collection. The Java Agent looks for jvm_direct:true in the instance section in the yaml file to change configuration.
      dd.jmxfetch.config
      Environment Variable: DD_JMXFETCH_CONFIG
      Default: null
      Example: path/to/file/conf.yaml,other/path/to/file/conf.yaml
      Additional metrics configuration file for JMX metrics collection. The Java Agent looks for jvm_direct:true in the instance section in the yaml file to change configuration.
      dd.jmxfetch.check-period
      Environment Variable: DD_JMXFETCH_CHECK_PERIOD
      Default: 1500
      How often to send JMX metrics (in ms).
      dd.jmxfetch.refresh-beans-period
      Environment Variable: DD_JMXFETCH_REFRESH_BEANS_PERIOD
      Default: 600
      How often to refresh list of available JMX beans (in seconds).
      dd.jmxfetch.statsd.host
      Environment Variable: DD_JMXFETCH_STATSD_HOST
      Default: Same as agent.host
      Statsd host to send JMX metrics to. If you are using Unix Domain Sockets, use an argument like ‘unix://PATH_TO_UDS_SOCKET’. Example: unix:///var/datadog-agent/dsd.socket
      dd.jmxfetch.statsd.port
      Environment Variable: DD_JMXFETCH_STATSD_PORT
      Default: 8125
      StatsD port to send JMX metrics to. If you are using Unix Domain Sockets, input 0.
      dd.integration.opentracing.enabled
      Environment Variable: DD_INTEGRATION_OPENTRACING_ENABLED
      Default: true
      By default the tracing client detects if a GlobalTracer is being loaded and dynamically registers a tracer into it. By turning this to false, this removes any tracer dependency on OpenTracing.
      dd.hystrix.tags.enabled
      Environment Variable: DD_HYSTRIX_TAGS_ENABLED
      Default: false
      By default the Hystrix group, command, and circuit state tags are not enabled. This property enables them.
      dd.trace.servlet.async-timeout.error
      Environment Variable: DD_TRACE_SERVLET_ASYNC_TIMEOUT_ERROR
      Default: true
      By default, long running asynchronous requests will be marked as an error, setting this value to false allows to mark all timeouts as successful requests.
      dd.trace.startup.logs
      Environment Variable: DD_TRACE_STARTUP_LOGS
      Default: true
      When false, informational startup logging is disabled. Available for versions 0.64+.
      dd.trace.servlet.principal.enabled
      Environment Variable: DD_TRACE_SERVLET_PRINCIPAL_ENABLED
      Default: false
      When true, user principal is collected. Available for versions 0.61+.

      Note:

      Integrations

      See how to disable integrations in the integrations compatibility section.

      Examples

      dd.service.mapping

      Example with system property:

      java -javaagent:/path/to/dd-java-agent.jar -Ddd.service=web-app -Ddd.service.mapping=postgresql:web-app-pg -jar path/to/application.jar
      service mapping

      dd.tags

      Setting a global env for spans and JMX metrics:

      java -javaagent:/path/to/dd-java-agent.jar -Ddd.service=web-app -Ddd.env=dev -jar path/to/application.jar
      trace global tags

      dd.trace.span.tags

      Example with adding project:test to every span:

      java -javaagent:/path/to/dd-java-agent.jar -Ddd.service=web-app -Ddd.env=dev -Ddd.trace.span.tags=project:test -jar path/to/application.jar
      trace span tags

      dd.trace.jmx.tags

      Setting custom.type:2 on a JMX metric:

      java -javaagent:/path/to/dd-java-agent.jar -Ddd.service=web-app -Ddd.env=dev -Ddd.trace.span.tags=project:test -Ddd.trace.jmx.tags=custom.type:2 -jar path/to/application.jar
      trace JMX tags

      dd.trace.methods

      Example with system property:

      java -javaagent:/path/to/dd-java-agent.jar -Ddd.service=web-app -Ddd.env=dev -Ddd.trace.methods="hello.GreetingController[doSomeStuff,doSomeOtherStuff];hello.Randomizer[randomize]" -jar path/to/application.jar
      trace methods

      dd.trace.db.client.split-by-instance

      Example with system property:

      java -javaagent:/path/to/dd-java-agent.jar -Ddd.env=dev -Ddd.service=web-app -Ddd.trace.db.client.split-by-instance=TRUE -jar path/to/application.jar

      DB Instance 1, webappdb, now gets its own service name that is the same as the db.instance span metadata:

      instance 1

      DB Instance 2, secondwebappdb, now gets its own service name that is the same as the db.instance span metadata:

      instance 2

      Similarly on the service map, you would now see one web app making calls to two different Postgres databases.

      dd.http.server.tag.query-string

      Example with system property:

      java -javaagent:/path/to/dd-java-agent.jar -Ddd.service=web-app -Ddd.env=dev -Ddd.http.server.tag.query-string=TRUE -jar path/to/application.jar
      query string

      dd.trace.enabled

      Example with system property and debug app mode:

      java -javaagent:/path/to/dd-java-agent.jar -Ddd.trace.enabled=false -Ddatadog.slf4j.simpleLogger.defaultLogLevel=debug -jar path/to/application.jar

      Debug app logs show that Tracing is disabled, not installing instrumentations.

      dd.jmxfetch.config.dir and dd.jmxfetch.config

      Example configuration:

      • Either the combination of: DD_JMXFETCH_CONFIG_DIR=<DIRECTORY_PATH> + DD_JMXFETCH_CONFIG=conf.yaml
      • Or directly: DD_JMXFETCH_CONFIG=<DIRECTORY_PATH>/conf.yaml

      With the following content for conf.yaml:

      init_config:
instances:
    - jvm_direct: true
      port: '<PORT>'
      conf:
          - include:
                bean:
                    - java.lang:type=MemoryPool,name=Metaspace
                attribute:
                    Usage.used:
                        metric_type: gauge
                        alias: sb.usage.used

      Would produce the following result:

      JMX fetch example

      See the Java integration documentation to learn more about Java metrics collection with JMX fetch.

      B3 headers extraction and injection

      Datadog APM tracer supports B3 headers extraction and injection for distributed tracing.

      Distributed headers injection and extraction is controlled by configuring injection/extraction styles. Currently two styles are supported:

      • Datadog: Datadog
      • B3: B3

      Injection styles can be configured using:

      • System Property: -Ddd.propagation.style.inject=Datadog,B3
      • Environment Variable: DD_PROPAGATION_STYLE_INJECT=Datadog,B3

      The value of the property or environment variable is a comma (or space) separated list of header styles that are enabled for injection. By default only Datadog injection style is enabled.

      Extraction styles can be configured using:

      • System Property: -Ddd.propagation.style.extract=Datadog,B3
      • Environment Variable: DD_PROPAGATION_STYLE_EXTRACT=Datadog,B3

      The value of the property or environment variable is a comma (or space) separated list of header styles that are enabled for extraction. By default only Datadog extraction style is enabled.

      If multiple extraction styles are enabled extraction attempt is done on the order those styles are configured and first successful extracted value is used.

      Trace reporting

      To report a trace to Datadog the following happens:

      • Trace completes
      • Trace is pushed to an asynchronous queue of traces
        • Queue is size-bound and doesn’t grow past a set limit of 7000 traces
        • Once the size limit is reached, traces are discarded
        • A count of the total traces is captured to ensure accurate throughput
      • In a separate reporting thread, the trace queue is flushed and traces are encoded via msgpack then sent to the Datadog Agent via http
      • Queue flushing happens on a schedule of once per second

      To see the actual code, documentation, and usage examples for any of the libraries and frameworks that Datadog supports, check the full list of auto-instrumented components for Java applications in the Integrations section.

      Trace annotation

      Add the dd-trace-api dependency to your project. For Maven, add this to pom.xml:

      <dependency>
    <groupId>com.datadoghq</groupId>
    <artifactId>dd-trace-api</artifactId>
    <version>{version}</version>
</dependency>

      For Gradle, add:

      implementation group: 'com.datadoghq', name: 'dd-trace-api', version: {version}

      Now add @Trace to methods to have them be traced when running with dd-java-agent.jar. If the Agent is not attached, this annotation has no effect on your application.

      @Trace annotations have the default operation name trace.annotation, while the method traced have the resource by default.

      Performance

      Java APM has minimal impact on the overhead of an application:

      • No collections maintained by Java APM grow unbounded in memory
      • Reporting traces does not block the application thread
      • Java APM loads additional classes for trace collection and library instrumentation

      Further Reading

      Additional helpful documentation, links, and articles:

      Datadog Java APM source codeGITHUB more more Explore your services, resources and tracesDOCUMENTATION more more