Local forwarder

Local forwarder is an agent that collects Application Insights or OpenCensus telemetry from a variety of SDKs and routes it to Application Insights. It's capable of running under Windows and Linux. You may also be able to run it under macOS, but that is not officially supported at this time.

Running local forwarder

Local forwarder is an open source project on GitHub. There are a variety of ways to run local forwarder on multiple platforms.

Windows

Windows Service

The easiest way of running local forwarder under Windows is by installing it as a Windows Service. The release comes with a Windows Service executable (WindowsServiceHost/Microsoft.LocalForwarder.WindowsServiceHost.exe) which can be easily registered with the operating system.

Note

The local forwarder service requires a minimum of .NET Framework 4.7. If you do not have .NET Framework 4.7 the service will install, but it won't start. To access the lastest version of the .NET Framework visit the .NET Framework download page.

  1. Download the LF.WindowsServiceHost.zip file from the local forwarder release page on GitHub.

    Screenshot of local forwarder release download page

  2. In this example for ease of demonstration, we will just extract the .zip file to the path C:\LF-WindowsServiceHost.

    To register the service and configure it to start at system boot run the following from the command line as Administrator:

    sc create "Local Forwarder" binpath="C:\LF-WindowsServiceHost\Microsoft.LocalForwarder.WindowsServiceHost.exe" start=auto
    

    You should receive a response of:

    [SC] CreateService SUCCESS

    To examine your new service via the Services GUI type services.msc

    Screenshot of local forwarder service

  3. Right-click the new local forwarder and select Start. Your service will now enter a running state.

  4. By default the service is created without any recovery actions. You can right-click and select Properties > Recovery to configure automatic responses to a service failure.

    Or if you prefer to set automatic recovery options programmatically for when failures occur, you can use:

    sc failure "Local Forwarder" reset= 432000 actions= restart/1000/restart/1000/restart/1000
    
  5. In the same location as your Microsoft.LocalForwarder.WindowsServiceHost.exe file, which in this example is C:\LF-WindowsServiceHost there is a file called LocalForwarder.config. This is an xml based file that allows you to adjust the configuration of your localforwader and specify the instrumentation key of the Application Insights resource you want your distributed tracing data forwarded.

    After editing the LocalForwarder.config file to add your instrumentation key, be sure to restart the Local Forwarder Service to allow your changes to take effect.

  6. To confirm that your desired settings are in place and that the local forwarder is listening for trace data as expected check the LocalForwarder.log file. You should see results similar to the image below at the bottom of the file:

    Screenshot of LocalForwarder.log file

Console application

For certain use cases, it might be beneficial to run local forwarder as a console application. The release comes with the following executable versions of the console host:

  • a framework-dependent .NET Core binary /ConsoleHost/publish/Microsoft.LocalForwarder.ConsoleHost.dll. Running this binary requires a .NET Core runtime to be installed; refer to this download page for details. batchfile E:\uncdrop\ConsoleHost\publish>dotnet Microsoft.LocalForwarder.ConsoleHost.dll
  • a self-contained .NET Core set of binaries for x86 and x64 platforms. These don't require .NET Core runtime to run. /ConsoleHost/win-x86/publish/Microsoft.LocalForwarder.ConsoleHost.exe, /ConsoleHost/win-x64/publish/Microsoft.LocalForwarder.ConsoleHost.exe. batchfile E:\uncdrop\ConsoleHost\win-x86\publish>Microsoft.LocalForwarder.ConsoleHost.exe E:\uncdrop\ConsoleHost\win-x64\publish>Microsoft.LocalForwarder.ConsoleHost.exe

Linux

As with Windows, the release comes with the following executable versions of the console host:

  • a framework-dependent .NET Core binary /ConsoleHost/publish/Microsoft.LocalForwarder.ConsoleHost.dll. Running this binary requires a .NET Core runtime to be installed; refer to this download page for details.
dotnet Microsoft.LocalForwarder.ConsoleHost.dll
  • a self-contained .NET Core set of binaries for linux-64. This one doesn't require .NET Core runtime to run. /ConsoleHost/linux-x64/publish/Microsoft.LocalForwarder.ConsoleHost.
user@machine:~/ConsoleHost/linux-x64/publish$ sudo chmod +x Microsoft.LocalForwarder.ConsoleHost
user@machine:~/ConsoleHost/linux-x64/publish$ ./Microsoft.LocalForwarder.ConsoleHost

Many Linux users will want to run local forwarder as a daemon. Linux systems come with a variety of solutions for service management, like Upstart, sysv, or systemd. Whatever your particular version is, you can use it to run local forwarder in a way that is most appropriate for your scenario.

As an example, let's create a daemon service using systemd. We'll use the framework-dependent version, but the same can be done for a self-contained one as well.

  • create the following service file named localforwarder.service and place it into /lib/systemd/system. This sample assumes your user name is SAMPLE_USER and you've copied local forwarder framework-dependent binaries (from /ConsoleHost/publish) to /home/SAMPLE_USER/LOCALFORWARDER_DIR.
# localforwarder.service
# Place this file into /lib/systemd/system/
# Use 'systemctl enable localforwarder' to start the service automatically on each boot
# Use 'systemctl start localforwarder' to start the service immediately

[Unit]
Description=Local Forwarder service
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
User=SAMPLE_USER
WorkingDirectory=/home/SAMPLE_USER/LOCALFORWARDER_DIR
ExecStart=/usr/bin/env dotnet /home/SAMPLE_USER/LOCALFORWARDER_DIR/Microsoft.LocalForwarder.ConsoleHost.dll noninteractive

[Install]
WantedBy=multi-user.target
  • Run the following command to instruct systemd to start local forwarder on every boot
systemctl enable localforwarder
  • Run the following command to instruct systemd to start local forwarder immediately
systemctl start localforwarder
  • Monitor the service by inspecting *.log files in the /home/SAMPLE_USER/LOCALFORWARDER_DIR directory.

Mac

Local forwarder may work with macOS, but it is currently not officially supported.

Self-hosting

Local forwarder is also distributed as a .NET Standard NuGet package, allowing you to host it inside your own .NET application.

using Library;
...
Host host = new Host();

// see section below on configuring local forwarder
string configuration = ...;

host.Run(config, TimeSpan.FromSeconds(5));
...
host.Stop();

Configuring local forwarder

  • When running one of local forwarder's own hosts (Console Host or Windows Service Host), you will find LocalForwarder.config placed next to the binary.
  • When self-hosting the local forwarder NuGet, the configuration of the same format must be provided in code (see section on self-hosting). For the configuration syntax, check the LocalForwarder.config in the GitHub repository.

Note

Configuration may change from release to release, so pay attention to which version you're using.

Monitoring local forwarder

Traces are written out to the file system next to the executable that runs local forwarder (look for *.log files). You can place a file with a name of NLog.config next to the executable to provide your own configuration in place of the default one. See documentation for the description of the format.

If no configuration file is provided (which is the default), Local forwarder will use the default configuration, which can be found here.

Next steps