windows-service

Run Node.JS programs as native Windows Services.

npm install windows-service
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This module implements the ability to run a Node.js based JavaScript program as a native Windows service.

This module is installed using node package manager (npm):

# This module contains C++ source code which will be compiled
# during installation using node-gyp.  A suitable build chain
# must be configured before installation.

npm install windows-service

It is loaded using the require() function:

var service = require ("windows-service");

A program can then be added, removed and run as a Windows service:

service.add ("My Service");

service.remove ("My Service");

var logStream = fs.createWriteStream ("my-service.log");

service.run (logStream, function () {
    console.log ("stop request received");
    service.stop ();
});

Batch Service Creation

Two approaches can be taken when adding and removing services.

In the first approach a program can be responsible for adding, removing and starting itself as a service. This is typically achieved by supporting program arguments such as --add, --remove, and --run, and executing the appropriate action.

The following example adds the calling program as a service when called with a --add parameter, and removes the created service when called with a --remove parameter:

if (process.argv[2] == "--add") {
    service.add ("My Service", {programArgs: ["--run"]});
} else if (process.argv[2] == "--remove") {
    service.remove ("My Service");
} else if (process.argv[2] == "--run") {
    var logStream = fs.createWriteStream (process.argv[1] + ".log");

    service.run (logStream, function () {
        service.stop (0);
    });

    // Run service program code...
} else {
    // Show usage...
}

Note the --run argument passed in the options parameter to the service.add() function. When the service is started using the Windows Service Control Manager the first argument to the program will be --run. The above program checks for this and if specified runs as a service using the service.run() function.

Also note that neither the node binary or the programs fully qualified path are specified. These parameters are automatically calculated it not specified. Refer to the service.add() function description for details about how this works.

In the second approach a dedicated service management program can be responsible for adding and removing many services in batch. The program adding and removing services is not a service itself, and would never call the service.run() function.

The following example adds or removes number of services:

if (program.argv[2] == "--add") {
    service.add ("Service 1", {programPath: "c:\example\service1.js"});
    service.add ("Service 2", {programPath: "c:\example\service2.js"});
    service.add ("Service 3", {programPath: "c:\example\service3.js"});
} else {
    service.remove ("Service 1");
    service.remove ("Service 2");
    service.remove ("Service 3");
}

Note that unlike the previous example the --run argument is not passed in the options parameter to the service.add() function. Since each service program does not add or remove itself as a service it only needs to run, and as such does not need to be told to so.

Also note that the programPath argument is passed in the options parameter to the service.add() function, to specify the fully qualified path to each service program - which would otherwise default to the service management program adding the services.

Each of the service programs can simply start themselves as services using the following code:

var logStream = fs.createWriteStream (process.argv[1] + ".log");

service.run (logStream, function () {
    service.stop (0);
});

// Run service program code...

Running Service Programs

When a service program starts it can always call the service.run() function regardless of whether it is started at the console, or by the Windows Service Control Manager.

When the service.run() function is called this module will attempt to connect to the Windows Service Control Manager so that control requests can be received - so that the service can be stopped.

When starting a program at the console an attempt to connect to the Windows Service Control Manager will fail. In this case the service.run() function will assume the program is running at the console and silently ignore this error.

This behaviour results in a program which can be run either at the console or the Windows Service Control Manager with no change.

Issues When Stopping Service Programs

The Windows Service Controller can sometimes report a service has failed to stop when in fact it has stopped.

The Windows Service Controller reports this on sporadic occasions, and after investigation nothing would suggest the service stop code behaves incorrectly. Therefore the error can be ignored.

The error can be reported even when the exact same sequence of events occur (i.e. all threads stop in the same order, and the service status is reported correctly).

Suggestions or solutions to this will be greatly received. Although this behaviour seems to cause no harm, it is nonetheless very annoying.

Current Working Directory

Upon starting the current working directory of a service program will be the "%windir%\system32" directory (i.e. c:\windows\system32). Service programs need to consider this when working with relative directory and file paths.

This path will most likely be different when running the same program at the console, so a service program may wish to change the current working directory to a more suitable location using the process.chdir() function to avoid different behaviour between the two methods of starting a program.

Using This Module

Given the intended purpose of this module only Windows platforms are supported.

However, this module aims to support other platforms in the future. That is it aims to support installing as a service on other platforms - by creating /etc/init.d/... scripts for example - so that the same service management code can be used to abstract away platform differences.

service.add (name, [options])

The add() function adds a Windows service.

The name parameter specifies the name of the created service. The optional options parameter is an object, and can contain the following items:

  • displayName - The services display name, defaults to the name parameter
  • nodePath - The fully qualified path to the node binary used to run the service (i.e. c:\Program Files\nodejs\node.exe, defaults to the value of process.execPath
  • nodeArgs - An array of strings specifying parameters to pass to nodePath, defaults to []
  • programPath - The program to run using nodePath, defaults to the value of process.argv[1]
  • programArgs - An array of strings specifying parameters to pass to programPath, defaults to []

The service will be set to automatically start at boot time, but not started. The service can be started using the net start "My Service" command.

An exception will be thrown if the service could not be added. The error will be an instance of the Error class.

The following example installs a service named My Service, it explicitly specifies the services display name, and specifies a number of parameters to the program:

var options = {
    displayName: "My Service",
    programArgs: ["--server-port", 8888]
};

service.add ("my-service", options);

service.remove (name)

The remove() function removes a Windows service.

The name parameter specifies the name of the service to remove. This will be the same name parameter specified when adding the service.

The service must be in a stopped state for it to be removed. The net stop "My Service" command can be used to stop the service before it is to be removed.

An exception will be thrown if the service could not be removed. The error will be an instance of the Error class.

The following example removes the service named My Service:

service.remove ("My Service");

service.run (stdoutLogStream, [stderrLogStream,] callback)

The run() function will connect the calling program to the Windows Service Control Manager, allowing the program to run as a Windows service.

The programs process.stdout stream will be replaced with the stdoutLogStream parameter, and the programs process.stderr stream replaced with the stdoutLogStream parameter (this allows the redirection of all console.log() type calls to a service specific log file). If the stderrLogStream parameter is not specified the programs process.stderr stream will be replaced with the stdoutLogStream parameter. The callback function will be called when the service receives a stop request, e.g. because the Windows Service Controller was used to send a stop request to the service.

The program should perform cleanup tasks and then call the service.stop() function.

The following example connects the calling program to the Windows Service Control Manager, it uses the same log stream for standard output and standard error:

var logStream = fs.createWriteStream ("my-service.log");

service.run (logStream, function () {
    console.log ("stop request received");
    service.stop ();
});

service.stop ([rcode])

The stop() function will cause the service to stop, and the calling program to exit.

Once the service has been stopped this function will terminate the program by calling the process.exit() function, passing to it the rcode parameter which defaults to 0. Before calling this function ensure the program has finished performing cleanup tasks.

BE AWARE, THIS FUNCTION WILL NOT RETURN.

The following example stops the calling program specifying a return code of 0, the function will not return:

var logStream = fs.createWriteStream ("my-service.log");

service.run (logStream, function () {
    console.log ("stop request received");
    service.stop (0);
});

Example Programs

Example programs are included under the modules example directory.

Bugs & Known Issues

None, yet!

Bug reports should be sent to stephen.vickers.sv@gmail.com.

Changes

Version 1.0.0 - 21/02/2013

  • Initial release

Version 1.0.1 - 11/05/2013

  • runInitialised was not set to true when the service is run() for the first time in index.js
  • Use MIT license instead of GPL

Version 1.0.2 - 15/08/2013

  • The variable rcode in the run() function defined in service.cc was not used

Roadmap

In no particular order:

  • Specify whether the service should auto-starting on boot
  • Add provisions for running under UNIX platforms (i.e. daemonize, conditional compile of C++ code for Windows only, create /etc/init.d/... scripts)

Suggestions and requirements should be sent to stephen.vickers.sv@gmail.com.

License

Copyright (c) 2013 Stephen Vickers

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Author

Stephen Vickers stephen.vickers.sv@gmail.com

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