How to use Environment Variables to hook into multiple .NET Applications Simultaneously

Overview

In Server version 3.7 and later, a new Environment Variable was introduced to hook into multiple .NET processes simultaneously. The VF_MULTI_AGENT_CONF_LOCATION allows Environment Variables to be used to hook the vFunction Agent into multiple processes while maintaining the ratio of one Agent per .NET process.

Steps to implement VF_MULTI_AGENT_CONF_LOCATION Environment Variable

Take the following steps to implement the VF_MULTI_AGENT_CONF_LOCATION Environment Variable:

  1. Log into the Windows Server where the .NET Applications run
  2. Create one vFunction instance for each .NET process to be monitored
  1. Open PowerShell as an Administrator
  2. Run the following command to create and install one instance, changing the $ALL_UPPER values
powershell -NoProfile -ExecutionPolicy unrestricted -Command "
$BASE_DIR\controller-installation\create-instance.ps1 -instance $NAME -agentMode true -type dotnet;New-Item -Path Env:\VF_CONTROLLER_$NAME_CONTROLLER_NAME -Value '$CHANGE_ME';
New-Item -Path Env:\VF_CONTROLLER_$NAME_CONTROLLER_HOST -Value '$CHANGE_ME';
New-Item -Path Env:\VF_CONTROLLER_$NAME_CONTROLLER_APP_ID -Value '$CHANGE_ME';
New-Item -Path Env:\VF_CONTROLLER_$NAME_CONTROLLER_ORG_ID -Value '$CHANGE_ME';
New-Item -Path Env:\VF_CONTROLLER_$NAME_CONTROLLER_CLIENT_ID -Value '$CHANGE_ME';
New-Item -Path Env:\VF_CONTROLLER_$NAME_CONTROLLER_CLIENT_SECRET -Value '$CHANGE_ME';
New-Item -Path Env:\VF_CONTROLLER_$NAME_CONTROLLER_INSTANCE_ID -Value '$CHANGE_ME';
New-Item -Path Env:\VF_CONTROLLER_$NAME_CONTROLLER_TAG -Value '$CHANGE_ME';
$BASE_DIR\controller-installation\install.ps1 -instance $NAME -scriptMode true"
  1. Repeat Step #2 for each .NET process that needs a vFunction instance
  1. Create a JSON file with references to each .NET process
  1. Find the Command Line entry for each running .NET process
  2. Create a vf_conf.json following the example format below for two .NET processes
[
    {
	"log_conf": {
		"level": "debug",
		"target_file": "$BASE_DIR\\vfunction\\log\\instances\\$NAME_1\\vfagent.net.log"
        },
		"instance": "$NAME_1",
		"shared_folder": "$BASE_DIR\\vfunction\\agent\\instances\\$NAME_1\\temp",
	    "cmd": "$CMD_LINE_FOR_PROCESS_1"
    },
    {
	"log_conf": {
		"level": "debug",
		"target_file": "$BASE_DIR\\vfunction\\log\\instances\\$NAME_2\\vfagent.net.log"
        },
		"instance": "$NAME_2",
		"shared_folder": "$BASE_DIR\\vfunction\\agent\\instances\\$NAME_2\\temp",
	    "cmd": "$CMD_LINE_FOR_PROCESS_2"		
    }
]
  1. Save the file to a location on the Windows Server, such as in the $BASE_DIR being used for the vFunction installation
  1. Add the System Environment Variables for the vFunction Agent. Note the distinct variable names depending on whether the process is a .NET Framework or .NET 3 /6 / 7 / 8 process. If both types of .NET Applications are running, create all of the Environment Variables
  1. Log onto the Windows Server
  2. Search for, Edit the System Environment Variables
  3. In the System Properties dialog box, click Environment Variables
  4. Click New below the System Variable list
  5. Create Variables for each of the fields below from the appropriate column
.NET Framework 4 Variable Name
.NET 3 / 6/ 7 / 8 Variable Name
Variable Value
VF_MULTI_AGENT_CONF_LOCATION VF_MULTI_AGENT_CONF_LOCATION $BASE_DIR\vf_conf.json
COR_ENABLE_PROFILING CORECLR_ENABLE_PROFILING 1
COR_PROFILER CORECLR_PROFILER {cd7d4b53-96c8-4552-9c11-6e41df8eab8a}
COR_PROFILER_PATH_64 CORECLR_PROFILER_PATH_64 $BASE_DIR\agent\vfagent.net.dll
COR_PROFILER_PATH_32 CORECLR_PROFILER_PATH_32 $BASE_DIR\agent\vfagent.net.x86.dll
COMPlus_TailCallOpt DOTNET_TailCallOpt 0
  1. Restart each .NET process

Updated on 15 May 2025