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Setup java agent

  1. Agent is available for JDK 8 - 12 in 7.x releases. JDK 1.6 - JDK 12 are supported in all 6.x releases NOTICE¹
  2. Find agent folder in SkyWalking release package
  3. Set agent.service_name in config/agent.config. Could be any String in English.
  4. Set collector.backend_service in config/agent.config. Default point to, only works for local backend.
  5. Add -javaagent:/path/to/skywalking-package/agent/skywalking-agent.jar to JVM argument. And make sure to add it before the -jar argument.

The agent release dist is included in Apache official release. New agent package looks like this.

+-- agent
    +-- activations
    +-- config
    +-- plugins
    +-- optional-plugins
    +-- bootstrap-plugins
    +-- logs
  • Start your application.

Supported middleware, framework and library

SkyWalking agent has supported various middlewares, frameworks and libraries. Read supported list to get them and supported version. If the plugin is in Optional² catalog, go to optional plugins section to learn how to active it.

Advanced features

  • All plugins are in /plugins folder. The plugin jar is active when it is in there. Remove the plugin jar, it disabled.
  • The default logging output folder is /logs.

Install javaagent FAQs

  • Linux Tomcat 7, Tomcat 8
    Change the first line of tomcat/bin/
CATALINA_OPTS="$CATALINA_OPTS -javaagent:/path/to/skywalking-agent/skywalking-agent.jar"; export CATALINA_OPTS
  • Windows Tomcat 7, Tomcat 8
    Change the first line of tomcat/bin/catalina.bat.
set "CATALINA_OPTS=-javaagent:/path/to/skywalking-agent/skywalking-agent.jar"
  • JAR file
    Add -javaagent argument to command line in which you start your app. eg:
java -javaagent:/path/to/skywalking-agent/skywalking-agent.jar -jar yourApp.jar
  • Jetty
    Modify, add -javaagent argument to command line in which you start your app. eg:
export JAVA_OPTIONS="${JAVA_OPTIONS} -javaagent:/path/to/skywalking-agent/skywalking-agent.jar"

Table of Agent Configuration Properties

This is the properties list supported in agent/config/agent.config.

property key Description Default
agent.namespace Namespace isolates headers in cross process propagation. The HEADER name will be HeaderName:Namespace. Not set
agent.service_name Application(5.x)/Service(6.x) code is showed in sky-walking-ui. Suggestion: set a unique name for each service, service instance nodes share the same code Your_ApplicationName
agent.sample_n_per_3_secs Negative or zero means off, by default.SAMPLE_N_PER_3_SECS means sampling N TraceSegment in 3 seconds tops. Not set
agent.authentication Authentication active is based on backend setting, see application.yml for more details.For most scenarios, this needs backend extensions, only basic match auth provided in default implementation. Not set
agent.span_limit_per_segment The max number of spans in a single segment. Through this config item, SkyWalking keep your application memory cost estimated. 300
agent.ignore_suffix If the operation name of the first span is included in this set, this segment should be ignored. Not set
agent.is_open_debugging_class If true, skywalking agent will save all instrumented classes files in /debugging folder. SkyWalking team may ask for these files in order to resolve compatible problem. Not set
agent.instance_uuid Instance uuid is the identity of an instance, SkyWalking treat same instance uuid as one instance.if empty, SkyWalking agent will generate an 32-bit uuid. Using NAME: as UUID prefix could set the customized instance name. Such as, set it as NAME:SVR-INSTANCE-A, SVR-INSTANCE-A is the instance name. Otherwise, use ServiceName-pid:id@hostname as the instance name. ""
agent.instance_properties[key]=value Add service instance custom properties. Not set
agent.cause_exception_depth How depth the agent goes, when log all cause exceptions. 5
agent.cool_down_threshold How long should the agent wait (in minute) before re-registering to the OAP server after receiving reset command. 10
agent.force_reconnection_period Force reconnection period of grpc, based on grpc_channel_check_interval. 1
agent.operation_name_threshold The operationName max length, setting this value > 500 is not recommended. 500
collector.grpc_channel_check_interval grpc channel status check interval. 30
collector.app_and_service_register_check_interval application and service registry check interval. 3
collector.backend_service Collector SkyWalking trace receiver service addresses.
collector.grpc_upstream_timeout How long grpc client will timeout in sending data to upstream. Unit is second. 30 seconds
collector.get_profile_task_interval Sniffer get profile task list interval. 20
logging.level The log level. Default is debug. DEBUG
logging.file_name Log file name. skywalking-api.log
logging.output Log output. Default is FILE. Use CONSOLE means output to stdout. FILE
logging.dir Log files directory. Default is blank string, means, use "{theSkywalkingAgentJarDir}/logs " to output logs. {theSkywalkingAgentJarDir} is the directory where the skywalking agent jar file is located ""
logging.pattern logging format. There are all conversion specifiers:
  * %level means log level.
  * %timestamp means now of time with format yyyy-MM-dd HH:mm:ss:SSS.
  * %thread means name of current thread.
  * %msg means some message which user logged.
  * %class means SimpleName of TargetClass.
  * %throwable means a throwable which user called.
  * %agent_name means agent.service_name
%level %timestamp %thread %class : %msg %throwable
logging.max_file_size The max size of log file. If the size is bigger than this, archive the current file, and write into a new file. 300 * 1024 * 1024
logging.max_history_files The max history log files. When rollover happened, if log files exceed this number,then the oldest file will be delete. Negative or zero means off, by default. -1
jvm.buffer_size The buffer size of collected JVM info. 60 * 10
buffer.channel_size The buffer channel size. 5
buffer.buffer_size The buffer size. 300
dictionary.service_code_buffer_size The buffer size of application codes and peer 10 * 10000
dictionary.endpoint_name_buffer_size The buffer size of endpoint names and peer 1000 * 10000 If true, skywalking agent will enable profile when user create a new profile task. Otherwise disable profile. true
profile.max_parallel Parallel monitor segment count 5
profile.duration Max monitor segment time(minutes), if current segment monitor time out of limit, then stop it. 10
profile.dump_max_stack_depth Max dump thread stack depth 500
profile.snapshot_transport_buffer_size Snapshot transport to backend buffer size 50
plugin.peer_max_length Peer maximum description limit. 200
plugin.mongodb.trace_param If true, trace all the parameters in MongoDB access, default is false. Only trace the operation, not include parameters. false
plugin.mongodb.filter_length_limit If set to positive number, the WriteRequest.params would be truncated to this length, otherwise it would be completely saved, which may cause performance problem. 256
plugin.elasticsearch.trace_dsl If true, trace all the DSL(Domain Specific Language) in ElasticSearch access, default is false. false
plugin.springmvc.use_qualified_name_as_endpoint_name If true, the fully qualified method name will be used as the endpoint name instead of the request URL, default is false. false
plugin.toolit.use_qualified_name_as_operation_name If true, the fully qualified method name will be used as the operation name instead of the given operation name, default is false. false
plugin.mysql.trace_sql_parameters If set to true, the parameters of the sql (typically java.sql.PreparedStatement) would be collected. false
plugin.mysql.sql_parameters_max_length If set to positive number, the db.sql.parameters would be truncated to this length, otherwise it would be completely saved, which may cause performance problem. 512
plugin.postgresql.trace_sql_parameters If set to true, the parameters of the sql (typically java.sql.PreparedStatement) would be collected. false
plugin.postgresql.sql_parameters_max_length If set to positive number, the db.sql.parameters would be truncated to this length, otherwise it would be completely saved, which may cause performance problem. 512
plugin.solrj.trace_statement If true, trace all the query parameters(include deleteByIds and deleteByQuery) in Solr query request, default is false. false
plugin.solrj.trace_ops_params If true, trace all the operation parameters in Solr request, default is false. false
plugin.light4j.trace_handler_chain If true, trace all middleware/business handlers that are part of the Light4J handler chain for a request. false
plugin.opgroup.* Support operation name customize group rules in different plugins. Read Group rule supported plugins Not set
plugin.springtransaction.simplify_transaction_definition_name If true, the transaction definition name will be simplified. false
plugin.jdkthreading.threading_class_prefixes Threading classes (java.lang.Runnable and java.util.concurrent.Callable) and their subclasses, including anonymous inner classes whose name match any one of the THREADING_CLASS_PREFIXES (splitted by ,) will be instrumented, make sure to only specify as narrow prefixes as what you're expecting to instrument, (java. and javax. will be ignored due to safety issues) Not set
plugin.tomcat.collect_http_params This config item controls that whether the Tomcat plugin should collect the parameters of the request. false
plugin.springmvc.collect_http_params This config item controls that whether the SpringMVC plugin should collect the parameters of the request, when your Spring application is based on Tomcat, consider only setting either plugin.tomcat.collect_http_params or plugin.springmvc.collect_http_params. false
plugin.http.http_params_length_threshold When COLLECT_HTTP_PARAMS is enabled, how many characters to keep and send to the OAP backend, use negative values to keep and send the complete parameters, NB. this config item is added for the sake of performance. 1024

Optional Plugins

Java agent plugins are all pluggable. Optional plugins could be provided in optional-plugins folder under agent or 3rd party repositories. For using these plugins, you need to put the target plugin jar file into /plugins.

Now, we have the following known optional plugins.

  • Plugin of tracing Spring annotation beans
  • Plugin of tracing Oracle and Resin
  • Filter traces through specified endpoint name patterns
  • Plugin of Gson serialization lib in optional plugin folder.
  • Plugin of Zookeeper 3.4.x in optional plugin folder. The reason of being optional plugin is, many business irrelevant traces are generated, which cause extra payload to agents and backends. At the same time, those traces may be just heartbeat(s).
  • Customize enhance Trace methods based on description files, rather than write plugin or change source codes.
  • Plugin of Spring Cloud Gateway 2.1.x in optional plugin folder. Please only active this plugin when you install agent in Spring Gateway. spring-cloud-gateway-2.x-plugin and spring-webflux-5.x-plugin are both required.
  • Plugin of Spring Transaction in optional plugin folder. The reason of being optional plugin is, many local span are generated, which also spend more CPU, memory and network.
  • Plugin of Kotlin coroutine provides the tracing across coroutines automatically. As it will add local spans to all across routines scenarios, Please assess the performance impact.

Bootstrap class plugins

All bootstrap plugins are optional, due to unexpected risk. Bootstrap plugins are provided in bootstrap-plugins folder. For using these plugins, you need to put the target plugin jar file into /plugins.

Now, we have the following known bootstrap plugins.

  • Plugin of JDK HttpURLConnection. Agent is compatible with JDK 1.6+
  • Plugin of JDK Callable and Runnable. Agent is compatible with JDK 1.6+

Advanced Features

Plugin Development Guide

SkyWalking java agent supports plugin to extend the supported list. Please follow our Plugin Development Guide.

If some RPC framework endpoints(server side) could include parameter, please read Operation Name Group Rule, and consider to add this feature.


If you are interested in plugin compatible tests or agent performance, see the following reports.


¹ Due to gRPC didn't support JDK 1.6 since 2018, SkyWalking abandoned the JDK 6/7 supports in all 7.x releases. But, with gRPC back forward compatibility(at least for now), all SkyWalking 6.x agents could work with 7.x, including the agent and backend.

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