os-service

This module implements the ability to run a Node.js based JavaScript program as a native Windows or Linux service.

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

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

npm install os-service

It is loaded using the require() function:

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

A program can then be added, removed and run as a 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"]}, function(error){ 
       if (error)
          console.trace(error);
    });
} else if (process.argv[2] == "--remove") {
    service.remove ("my-service", function(error){ 
       if (error)
          console.trace(error);
    });
} 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, or the Linux service management facilities, 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 ("service1", {programPath: "c:\example\svc1.js",
        function(error) { 
            if (error) {
                console.trace(error);
            } else {
                service.add ("service2", {programPath: "c:\example\svc2.js",
                    function(error) { 
                        if (error) {
                            console.trace(error);
                        }
                    });
            }
        });
} else {
    service.remove ("service2", function(error) { 
        if (error) {
            console.trace(error);
        } else {
            service.remove ("service1", function(error) { 
                if (error) {
                    console.trace(error);
                }
            });
        }
    });
}

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, by the Windows Service Control Manager, or the Linux service management facilities.

On Windows, 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.

On Linux, services started at the console will run in the foreground, this allows command sequences such as CTRL+C to be used, e.g. during development. When Linux services are started using the Linux service management facilities, i.e. service my-service start, they can be stopped using the signals SIGINT and SIGTERM, or again using the Linux service management facilities, i.e. service my-service stop.

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

Current Working Directory

Upon starting the current working directory of a service program will be platform specific the , e.g. the "%windir%\system32" directory on Windows. 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

This module attempts to behave in exactly the same way on Windows and Linux platforms - at least the API is exactly the same for both platforms both from a service management and service running perspective.

On Windows platforms the Windows Service Control Manager WIN32 API is used to manage services. On Linux platforms the chkconfig command is used, and if not available, the update-rc.d command is used instead.

service.add (name, [options], cb)

The add() function adds a 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
  • this parameter will be used on Windows platforms only
• 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 []
• runLevels - An array of numbers specifying Linux run-levels at which the service should be started for Linux platforms, defaults to [2, 3, 4, 5]
• username - For Windows platforms a username and password can be specified, the service will be run using these credentials when started, see the CreatedService() functions win32 API documentation for details on the format of the username, on all other platforms this parameter is ignored
• password - See the username parameter

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 on Windows and service my-service start on Linux.

The cb callback function is called once the service has been added. The following arguments will be passed to the callback function:

• error - Instance of the Error class, or null if no error occurred

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: "MyService",
    programArgs: ["--server-port", 8888],
    username: ".\Stephen Vickers",
    password: "MyPassword :)"
};

service.add ("my-service", options, function(error) {
    if (error)
        console.trace(error);
});

service.remove (name, cb)

The remove() function removes a 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 on Windows and the service my-service stop on Linux before it is to be removed.

The cb callback function is called once the service has been removed. The following arguments will be passed to the callback function:

• error - Instance of the Error class, or null if no error occurred

The following example removes the service named my-service:

service.remove ("my-service", function(error) {
    if (error)
        console.trace(error);
});

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

The run() function will attempt to run the program as a 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, or a SIGTERM signal was received.

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

The following example starts a program as a service, 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 [email protected].

Changes

Version 1.0.0 - 30/12/2014

• Initial release

Version 1.0.1 - 03/03/2015

• Support Linux platforms which don't have the start-stop-daemon program

Version 1.0.2 - 30/03/2015

• Linux start/stop link under /etc/rcN.d directories are not removed

Version 1.0.3 - 22/09/2015

• Host repository on GitHub

Version 1.1.0 - 09/10/2015

• Migrate C++ addon code to use the Native Abstractions for Node framework
• Add missing shebang line '#!' to start/stop script template
• Not possible to specify run levels for Linux start/stop script (added new runLevels item to the options parameter to the add() function

Version 1.1.1 - 08/02/2016

• Remove extraneous semicolon from the README.md file

Version 1.2.0 - 29/02/2016

• On Windows platforms allow users to specify a username/password with which a service should be run, the username and password options parameters were added to the add() function

Version 1.3.0 - 15/05/2016

• Require nan 2.3.x to support node version 6

Roadmap

Suggestions and requirements should be sent to [email protected].

License

Copyright (c) 2014 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 [email protected]