Package net.bytebuddy.agent

Class Attacher

java.lang.Object

net.bytebuddy.agent.Attacher

public class Attacher
extends Object

A Java program that attaches a Java agent to an external process.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	ARGUMENT_ENVIRONMENT_VARIABLE	The environment variable that supplies the agent argument.
static final String	DUMP_PROPERTY	Indicates that any error during attachment should be dumped to a given file location.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Attacher()	The attacher provides only static utility methods and should not be instantiated.

Method Summary

Modifier and Type	Method	Description
protected static void	install(Class<?> virtualMachineType, String processId, String agent, boolean isNative, String argument)	Installs a Java agent on a target VM.
static void	main(String[] args)	Runs the attacher as a Java application.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DUMP_PROPERTY

public static final String DUMP_PROPERTY

Indicates that any error during attachment should be dumped to a given file location. When set for external attachment, diagnostic information is appended to this file.

See Also:

• Constant Field Values

ARGUMENT_ENVIRONMENT_VARIABLE

public static final String ARGUMENT_ENVIRONMENT_VARIABLE

The environment variable that supplies the agent argument. The argument is not supplied as a command line argument as the arguments of a process can be read by other users of the same host, for example by reading /proc/[pid]/cmdline on a Linux host, such that the argument is not exposed to them unnecessarily.

See Also:

• Constant Field Values

Constructor Details

Attacher

private Attacher()

The attacher provides only static utility methods and should not be instantiated.

Method Details

main

public static void main(String[] args)

Runs the attacher as a Java application.

Parameters:

args - A list containing the fully qualified name of the virtual machine type, the process id, the fully qualified name of the Java agent jar followed by an empty string if the argument to the agent is null or any number of strings where the first argument is proceeded by any single character which is stripped off. The agent argument is only read from this list if it is not supplied by the ARGUMENT_ENVIRONMENT_VARIABLE environment variable which is preferred to avoid its exposure on the command line.

install

protected static void install(Class<?> virtualMachineType,
 String processId,
 String agent,
 boolean isNative,
 @MaybeNull
 String argument)
                       throws NoSuchMethodException,
InvocationTargetException,
IllegalAccessException

Installs a Java agent on a target VM.

Parameters:

virtualMachineType - The virtual machine type to use for the external attachment.

processId - The id of the process being target of the external attachment.

agent - The Java agent to attach.

isNative - true if the agent is native.

argument - The argument to provide or null if no argument is provided.

Throws:

NoSuchMethodException - If the virtual machine type does not define an expected method.

InvocationTargetException - If the virtual machine type raises an error.

IllegalAccessException - If a method of the virtual machine type cannot be accessed.