Support custom enhance

Here is an optional plugin apm-customize-enhance-plugin

Introduce

SkyWalking has provided Java agent plugin development guide to help developers to build new plugin.

This plugin is not designed for replacement but for user convenience. The behaviour is very similar with @Trace toolkit, but without code change requirement, and more powerful, such as provide tag and log.

How to configure

Implementing enhancements to custom classes requires two steps.

1. Active the plugin, move the optional-plugins/apm-customize-enhance-plugin.jar to plugin/apm-customize-enhance-plugin.jar.
2. Set plugin.customize.enhance_file in agent.config, which targets to rule file, such as /absolute/path/to/customize_enhance.xml.
3. Set enhancement rules in customize_enhance.xml.

   <?xml version="1.0" encoding="UTF-8"?>
   <enhanced>
       <class class_name="test.apache.skywalking.testcase.customize.service.TestService1">
           <method method="staticMethod()" operation_name="/is_static_method" static="true"/>
           <method method="staticMethod(java.lang.String,int.class,java.util.Map,java.util.List,[Ljava.lang.Object;)" operation_name="/is_static_method_args" static="true">
               <operation_name_suffix>arg[0]</operation_name_suffix>
               <operation_name_suffix>arg[1]</operation_name_suffix>
               <operation_name_suffix>arg[3].[0]</operation_name_suffix>
               <tag key="tag_1">arg[2].['k1']</tag>
               <tag key="tag_2">arg[4].[1]</tag>
               <log key="log_1">arg[4].[2]</log>
           </method>
           <method method="method()" static="false"/>
           <method method="method(java.lang.String,int.class)" operation_name="/method_2" static="false">
               <operation_name_suffix>arg[0]</operation_name_suffix>
               <tag key="tag_1">arg[0]</tag>
               <log key="log_1">arg[1]</log>
           </method>
           <method method="method(test.apache.skywalking.testcase.customize.model.Model0,java.lang.String,int.class)" operation_name="/method_3" static="false">
               <operation_name_suffix>arg[0].id</operation_name_suffix>
               <operation_name_suffix>arg[0].model1.name</operation_name_suffix>
               <operation_name_suffix>arg[0].model1.getId()</operation_name_suffix>
               <tag key="tag_os">arg[0].os.[1]</tag>
               <log key="log_map">arg[0].getM().['k1']</log>
           </method>
       </class>
       <class class_name="test.apache.skywalking.testcase.customize.service.TestService2">
           <method method="staticMethod(java.lang.String,int.class)" operation_name="/is_2_static_method" static="true">
               <tag key="tag_2_1">arg[0]</tag>
               <log key="log_1_1">arg[1]</log>
           </method>
           <method method="method([Ljava.lang.Object;)" operation_name="/method_4" static="false">
               <tag key="tag_4_1">arg[0].[0]</tag>
           </method>
           <method method="method(java.util.List,int.class)" operation_name="/method_5" static="false">
               <tag key="tag_5_1">arg[0].[0]</tag>
               <log key="log_5_1">arg[1]</log>
           </method>
       </class>
   </enhanced>
   

   ``

• Explanation of the configuration in the file

  configuration	explanation
  class_name	The enhanced class
  method	The interceptor method of the class
  operation_name	If fill it out, will use it instead of the default operation_name.
  operation_name_suffix	What it means adding dynamic data after the operation_name.
  static	Is this method static.
  tag	Will add a tag in local span. The value of key needs to be represented on the XML node.
  log	Will add a log in local span. The value of key needs to be represented on the XML node.
  arg[x]	What it means is to get the input arguments. such as arg[0] is means get first arguments.
  .[x]	When the parsing object is Array or List, you can use it to get the object at the specified index.
  .[‘key’]	When the parsing object is Map, you can get the map ‘key’ through it.