npm package: @koush/node-windows
Description: Support for Windows services, event logging, UAC, and several helper methods for interacting with the OS.
Author: Corey Butler
Latest version: 1.0.1

# node-windows

![NPM version](https://img.shields.io/npm/v/node-windows?label=node-windows&logo=npm&style=for-the-badge)
![NGN Dependencies](https://img.shields.io/librariesio/release/npm/node-windows?style=for-the-badge)

 This library can be used to install/start/stop/uninstall Node scripts as Windows background services for **production** environments. This is not a tool for developing applications, it is a tool for releasing them. 

  See [node-mac](http://github.com/coreybutler/node-mac) and [node-linux](http://github.com/coreybutler/node-linux) if you need to support those operating systems.
    
[Tweet me (@goldglovecb)](http://twitter.com/goldglovecb) if you need me.

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## Overview

The following features are available in node-windows:

- **Service Management**: Run Node.js scripts as native Windows services. Includes monitoring.
- **Event Logging**: Create logs in the Event log.
- **Commands**:
  - _Elevated Permissions_: Run a command with elevated privileges (may prompt user for acceptance)
  - _Sudo_: Run an `exec` command as a sudoer.
  - _Identify Administrative Privileges_: Determines whether the current user has administrative privileges.
  - _List Tasks_: A method to list running windows tasks/services.
  - _Kill Task_: A method to kill a specific windows service/task (by PID).

## Installation

The recommended way to install node-windows is with npm, using the global flag:

`npm install -g node-windows`

Then, in your project root, run:

`npm link node-windows`

However; it is possible to use node-windows without the global flag (i.e. install directly into the project root).
More details regarding why this is not the recommended approach are available throughout this Readme.

## NO NATIVE MODULES

Using native node modules on Windows can suck. Most native modules are not distributed in a binary format.
Instead, these modules rely on `npm` to build the project, utilizing [node-gyp](https://github.com/TooTallNate/node-gyp).
This means developers need to have Visual Studio (and potentially other software) installed on the system,
just to install a native module. This is portable, but painful... mostly because Visual Studio
itself is over 2GB.

**node-windows does not use native modules.** There are some binary/exe utilities, but everything
needed to run more complex tasks is packaged and distributed in a readily usable format. So, no need for
Visual Studio... at least not for this module.

---

# Windows Services

node-windows has a utility to run Node.js scripts as Windows services. Please note that like all
Windows services, creating one requires administrative privileges. To create a service with
node-windows, prepare a script like:

```js
var Service = require('node-windows').Service;

// Create a new service object
var svc = new Service({
  name:'Hello World',
  description: 'The nodejs.org example web server.',
  script: 'C:\\path\\to\\helloworld.js',
  nodeOptions: [
    '--harmony',
    '--max_old_space_size=4096'
  ]
  //, workingDirectory: '...'
  //, allowServiceLogon: true
});

// Listen for the "install" event, which indicates the
// process is available as a service.
svc.on('install',function(){
  svc.start();
});

svc.install();
```

The code above creates a new `Service` object, providing a pretty name and description.
The `script` attribute identifies the Node.js script that should run as a service. Upon running
this, the script will be visible from the Windows Services utility.

![Windows Service](https://raw.github.com/coreybutler/node-windows/master/docs/service.png)

The `Service` object emits the following events:

- _install_ - Fired when the script is installed as a service.
- _alreadyinstalled_ - Fired if the script is already known to be a service.
- _invalidinstallation_ - Fired if an installation is detected but missing required files.
- _uninstall_ - Fired when an uninstallation is complete.
- _alreadyuninstalled_ - Fired when an uninstall is requested and no installation exists.
- _start_ - Fired when the new service is started.
- _stop_ - Fired when the service is stopped.
- _error_ - Fired in some instances when an error occurs.

In the example above, the script listens for the `install` event. Since this event
is fired when a service installation is complete, it is safe to start the service.

Services created by node-windows are similar to most other services running on Windows.
They can be started/stopped from the windows service utility, via `NET START` or `NET STOP` commands,
or even managed using the <a href="http://technet.microsoft.com/en-us/library/dd228922(v=ws.10).aspx">sc</a>
utility.

### Command-line Options

It may be desired to specify command-line switches to your script. You can do this by setting the `scriptOptions` within the service config:

```js
var svc = new Service({
  name:'Hello World',
  description: 'The nodejs.org example web server.',
  script: 'C:\\path\\to\\helloworld.js',
  scriptOptions: '-c C:\\path\\to\\somewhere\\special -i'
});
```


### Environment Variables

Sometimes you may want to provide a service with static data, passed in on creation of the service. You can do this by setting environment variables in the service config, as shown below:

```js
var svc = new Service({
  name:'Hello World',
  description: 'The nodejs.org example web server.',
  script: 'C:\\path\\to\\helloworld.js',
  env: {
    name: "HOME",
    value: process.env["USERPROFILE"] // service is now able to access the user who created its' home directory
  }
});
```
You can also supply an array to set multiple environment variables:

```js
var svc = new Service({
  name:'Hello World',
  description: 'The nodejs.org example web server.',
  script: 'C:\\path\\to\\helloworld.js',
  env: [{
    name: "HOME",
    value: process.env["USERPROFILE"] // service is now able to access the user who created its' home directory
  },
  {
    name: "TEMP",
    value: path.join(process.env["USERPROFILE"],"/temp") // use a temp directory in user's home directory
  }]
});
```


### Node Executable Path

There are times when you may want to specify a specific `node` executable to use to run your script. You can do this by setting the `execPath` in the service config, as shown below:

```js
var svc = new Service({
  name:'Hello World',
  description: 'The nodejs.org example web server.',
  script: 'C:\\path\\to\\helloworld.js',
  execPath: 'C:\\path\\to\\specific\\node.exe'
});
```


### User Account Attributes

If you need to specify a specific user or particular credentials to manage a service, the following
attributes may be helpful.

The `user` attribute is an object with three keys: `domain`,`account`, and `password`.
This can be used to identify which user the service library should use to perform system commands.
By default, the domain is set to the local computer name, but it can be overridden with an Active Directory
or LDAP domain. For example:

**app.js**
```js
var Service = require('node-windows').Service;

// Create a new service object
var svc = new Service({
  name:'Hello World',
  script: require('path').join(__dirname,'helloworld.js'),
  //, allowServiceLogon: true 
});

svc.logOnAs.domain = 'mydomain.local';
svc.logOnAs.account = 'username';
svc.logOnAs.password = 'password';
...
```

Both the account and password must be explicitly defined if you want the service module to
run commands as a specific user. By default, it will run using the user account that launched
the process (i.e. who launched `node app.js`).

If you want to instruct winsw to allow service account logins, specify `allowServiceLogon: true`. This is disabled by default since some users have experienced issues running this without service logons.

The other attribute is `sudo`. This attribute has a single property called `password`. By supplying
this, the service module will attempt to run commands using the user account that launched the
process and the password for that account. This should only be used for accounts with administrative
privileges.

**app.js**
```js
var Service = require('node-windows').Service;

// Create a new service object
var svc = new Service({
  name:'Hello World',
  script: require('path').join(__dirname,'helloworld.js')
});

svc.sudo.password = 'password';
...
```

### Cleaning Up: Uninstall a Service

Uninstalling a previously created service is syntactically similar to installation.

```js
var Service = require('node-windows').Service;

// Create a new service object
var svc = new Service({
  name:'Hello World',
  script: require('path').join(__dirname,'helloworld.js')
});

// Listen for the "uninstall" event so we know when it's done.
svc.on('uninstall',function(){
  console.log('Uninstall complete.');
  console.log('The service exists: ',svc.exists);
});

// Uninstall the service.
svc.uninstall();
```

The uninstall process only removes process-specific files. **It does NOT delete your Node.js script!**

### What Makes node-windows Services Unique?

Lots of things!

**Long Running Processes & Monitoring:**

The built-in service recovery for Windows services is fairly limited and cannot easily be configured
from code. Therefore, node-windows creates a wrapper around the Node.js script. This wrapper
is responsible for restarting a failed service in an intelligent and configurable manner. For example,
if your script crashes due to an unknown error, node-windows will attempt to restart it. By default,
this occurs every second. However; if the script has a fatal flaw that makes it crash repeatedly,
it adds unnecessary overhead to the system. node-windows handles this by increasing the time interval
between restarts and capping the maximum number of restarts.

**Smarter Restarts That Won't Pummel Your Server:**

Using the default settings, node-windows adds 25% to the wait interval each time it needs to restart
the script. With the default setting (1 second), the first restart attempt occurs after one second.
The second occurs after 1.25 seconds. The third after 1.56 seconds (1.25 increased by 25%) and so on.
Both the initial wait time and the growth rate are configuration options that can be passed to a new
`Service`. For example:

```js
var svc = new Service({
  name:'Hello World',
  description: 'The nodejs.org example web server.',
  script: 'C:\\path\\to\\helloworld.js',
  wait: 2,
  grow: .5
});
```

In this example, the wait period will start at 2 seconds and increase by 50%. So, the second attempt
would be 3 seconds later while the fourth would be 4.5 seconds later.

**Don't DOS Yourself!**

Repetitive recycling could potentially go on forever with a bad script. To handle these situations, node-windows
supports two kinds of caps. Using `maxRetries` will cap the maximum number of restart attempts. By
default, this is unlimited. Setting it to 3 would tell the process to no longer restart a process
after it has failed 3 times. Another option is `maxRestarts`, which caps the number of restarts attempted
within 60 seconds. For example, if this is set to 3 (the default) and the process crashes/restarts repeatedly,
node-windows will cease restart attempts after the 3rd cycle in a 60 second window. Both of these
configuration options can be set, just like `wait` or `grow`.

Finally, an attribute called `abortOnError` can be set to `true` if you want your script to **not** restart
at all when it exits with an error.

### How Services Are Made

node-windows uses the [winsw](https://github.com/kohsuke/winsw) utility to create a unique `.exe`
for each Node.js script deployed as a service. A directory called `daemon` is created and populated
with `myappname.exe` and `myappname.xml`. The XML file is a configuration for the executable. Additionally,
`winsw` will create some logs for itself in this directory (which are viewable in the Event log).

The `myappname.exe` file launches the node-windows wrapper, which is responsible for monitoring and managing
the script. Since this file is a part of node-windows, moving the node-windows directory could result in
the `.exe` file not being able to find the Node.js script. However; this should not be a problem if
node-windows is installed globally, per the recommended installation instructions.

All of these daemon-specific files are created in a subdirectory called `daemon`, which is created in the
same directory where the Node.js script is saved. Uninstalling a service will remove these files.

_Event Logging_

Services created with node-windows have two event logs that can be viewed through the Windows Event Viewer.
A log source named `myappname.exe` provides basic logging for the executable file. It can be used to see
when the entire service starts/stops or has errors. A second log, named after your service name (i.e. My App Name),
is used by the node-windows monitor. It is possible to write to this log from the Node.js script using
the node-windows Event Logging.

---

# Event Logging

New as of `v0.1.0` is a _non-C++_ based event logging utility. This utility can write to the event log,
making your logs visible from the Event Viewer.

To create a logger:

```js
var EventLogger = require('node-windows').EventLogger;

var log = new EventLogger('Hello World');

log.info('Basic information.');
log.warn('Watch out!');
log.error('Something went wrong.');
```

Looks similar to:

![Event Logging in node-windows](https://raw.github.com/coreybutler/node-windows/master/docs/eventlog.png)

Some lesser-used options are also available through node-windows event logging.

```js
log.auditSuccess('AUser Login Success');
log.auditFailure('AUser Login Failure');
```

Each log type (info, warn, error, auditSuccess, and auditFailure) method optionally accepts two additional
arguments, including a _code_ and _callback_. By default, the event code is `1000` if not otherwise specified.
To provide a custom event code with a log message and write that message to the console, the following code could
be used:

```js
log.info('Something different happened!', 1002, function(){
  console.log('Something different happened!');
});
```

By default, event logs are all part of the `APPLICATION` scope. However; it is also possible to use the `SYSTEM` log.
To do this, a configuration object must be passed to the new log:

```js
var EventLogger = require('node-windows').EventLogger;
var log = new EventLogger({
  source: 'My Event Log',
  eventLog: 'SYSTEM'
});
```

---

# Commands

node-windows ships with several commands to simplify tasks on MS Windows.

## elevate

Elevate is similar to `sudo` on Linux/Mac. It attempts to elevate the privileges of the
current user to a local administrator. Using this does not require a password, but it
does require that the current user have administrative privileges. Without these
privileges, the command will fail with a `access denied` error.

On systems with UAC enabled, this may prompt the user for permission to proceed:

![UAC Prompt](http://upload.wikimedia.org/wikipedia/en/5/51/Windows_7_UAC.png)

**Syntax**:

`elevate(cmd[,options,callback])`

- _cmd_: The command to execute with elevated privileges. This can be any string that would be typed at the command line.
- _options_ (optional): Any options that will be passed to `require('child_process').exec(cmd,<OPTIONS>,callback)`.
- _callback_ (optional): The callback function passed to `require('child_process').exec(cmd,options,<CALLBACK>)`.

## sudo

Sudo acts similarly to `sudo` on Linux/Mac. Unlike _elevate_, it requires a password, but it
will not prompt the user for permission to proceed. Like _elevate_, this
_still requires administrative privileges_ for the user, otherwise the command will fail.
The primary difference between this and _elevate()_ is the prompt.

**Syntax**:

`sudo(cmd,password[,options,callback])`

- _cmd_: The command to execute with elevated privileges. This can be any string that would be typed at the command line.
- _password_: The password of the user
- _options_ (optional): Any options that will be passed to `require('child_process').exec(cmd,<OPTIONS>,callback)`.
- _callback_ (optional): The callback function passed to `require('child_process').exec(cmd,options,<CALLBACK>)`.

## isAdminUser

This asynchronous command determines whether the current user has administrative privileges.
It passes a boolean value to the callback, returning `true` if the user is an administrator
or `false` if it is not.

**Example**

```js
var wincmd = require('node-windows');

wincmd.isAdminUser(function(isAdmin){
  if (isAdmin) {
    console.log('The user has administrative privileges.');
  } else {
    console.log('NOT AN ADMIN');
  }
});
```

## list

The list method queries the operating system for a list of running processes.

```js
var wincmd = require('node-windows');

wincmd.list(function(svc){
  console.log(svc);
},true);
```

This returns an array of running processes. Supplying the optional `true`
argument in the above example provides a list with verbose output. The output is
specific to the version of the operating system. Here is an example of verbose
output on a Windows 8 computer.

```js
[{
  ImageName: 'cmd.exe',
  PID: '12440',
  SessionName: 'Console',
  'Session#': '1',
  MemUsage: '1,736 K',
  Status: 'Unknown',
  UserName: 'Machine\\Corey',
  CPUTime: '0:00:00',
  WindowTitle: 'N/A'
},{
  ImageName: 'tasklist.exe',
  PID: '1652',
  SessionName: 'Console',
  'Session#': '1',
  MemUsage: '8,456 K',
  Status: 'Unknown',
  UserName: 'Machine\\Corey',
  CPUTime: '0:00:00',
  WindowTitle: 'N/A'
}]
```

The regular (non-verbose) output typically provides the `ImageName`,`PID`,`SessionName`,
`Session#`, `MemUsage`, and `CPUTime`.

## kill

This method will kill a process by `PID`.


```js
var wincmd = require('node-windows');

wincmd.kill(12345,function(){
  console.log('Process Killed');
});
```

In this example, process ID `12345` would be killed. It is important to note that the
user account executing this node script may require administrative privileges.

# Troubleshooting

If you're experiencing issues with the examples, please review the `TESTS.md` file.

If you are encountering the _invalidinstallation_ event, take a look at the `daemon`
directory that is created during the installation to make sure the `.exe` and `.xml`
files are there. In some circumstances, primarily during _un_installation, it is
possbile for the process to temporarily lock a log file, which prevents Windows
from removing it. In this scenario, simply run the uninstall again. In most cases this
will fix the issue. If not, manually remove the `daemon` directory before running the
installation again.

# Thank You

There have been many contributors who have done everything from committing features to helping pick up slack while I've been swamped. I'm incredibly appreciative for the help.

Special thanks to @arthurblake whose modifications have FINALLY been added. Thanks to @hockeytim11, who helped compile and update a bunch of outstanding issues and started bringing support to the other node-* libraries.

# Licenses

winsw and sudowin are the copyrights of their respective owners. winsw
is distributed under an MIT license. sudowin is distributed under a BSD license.

All other scripts are Copyright (c) Corey Butler under an MIT license.

(The MIT License)

Copyright (c) 2013 Corey Butler

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.