io-event-reactor-plugin-shell-exec

Shell exec filesystem event reactor plugin for: io-event-reactor that utilizes stateful-process-command-proxy for executing system commands in any shell (bash, sh, powershell, ksh, whatever)

Usage

To configure this ReactorPlugin in your application that uses io-event-reactor do the following

npm install io-event-reactor-plugin-shell-exec

Then in your io-event-reactor configuration object that you pass to the IoReactorService constructor, you can specify this plugin in the reactors block as so:

var ioReactorServiceConf = {

  ...

  ioReactors: [

          {
              id: "reactor1",

              monitor: {
                  ...
              },

              evaluators: [
                  {
                      evaluator: myEvaluatorFunction,
                      reactors: ['shellExec1,...'] // binds shell-exec to this evaluator
                  }
              ],

              reactors: [

                  // the "id" is what you use to bind this reactor
                  // to an evaluator above
                  { id: "shellExec1",

                    plugin: "io-event-reactor-plugin-shell-exec",

                    config: {

                        // Configuration for stateful-process-command-proxy
                        // for options see: https://github.com/bitsofinfo/stateful-process-command-proxy
                        statefulProcessCommandProxy: {

                            // instance: refToExistingInstance
                            // OR
                            // pass a new config
                            
                            config: {
                                name: "whateverYouWant",
                                max: 2,
                                min: 1,
                                idleTimeoutMS: 120000,
                                logFunction: yourLoggerFunction,
                                processCommand: '/bin/bash',
                                processArgs:  ['-s'],
                                processRetainMaxCmdHistory : 10,
                                processCwd : './',
                                validateFunction: function(processProxy) {
                                    return processProxy.isValid();
                                }
                            }
                        },

                        /**
                        * 'commandTemplates' - an array of mustache (https://github.com/janl/mustache.js) command template strings
                        *                   that will be executed in order using node-mysql when this plugin's react() is invoked.
                        *
                        *  Supported mustache template variables that will be made available to you: (a full IoEvent)
                        *    - see https://github.com/bitsofinfo/io-event-reactor-plugin-support for IoEvent definition
                        *    - ioEvent.uuid
                        *    - ioEvent.eventType: one of: 'add', 'addDir', 'unlink', 'unlinkDir', 'change'
                        *    - ioEvent.fullPath: string full path to file being reacted to (filename/dir inclusive)
                        *    - ioEvent.parentPath: full path to the directory containing the item manipulated
                        *    - ioEvent.filename: filename/dirname only (no path information)
                        *    - ioEvent.optionalFsStats: optional stats object -> https://nodejs.org/docs/latest/api/fs.html#fs_class_fs_stats
                        *    - ioEvent.optionalExtraInfo: optional object, see the MonitorPlugin you are using to see the spec and when/if its available
                        */
                        commandTemplates: [
                            'cp {{{ioEvent.fullpath}}} /some/other/dir'
                        ],

                        /**
                        * 'commandGenerator' - callback function(ioEvent) that must return an array[] of command statements
                        *                     literals that will be executed in order using
                        *                     stateful-process-command-proxy when this plugin's react() is invoked.
                        */
                        commandGenerator: function(ioEvent) {
                          return [('cp '+ioEvent.fullpath+' /some/other/dir')];
                        }
                     }
                  },

                  ....
              ]
        },
        ....
    ]

    ...
};

Security

Be aware that this plugin takes raw input from events generated by a monitor plugin and allows you to use that data in shell statements that will be executed on your operating system. This potentially could open you up to certain edge cases where command injection could occur. If you are concerned about this you may only want to use the commandGenerator option to pre-santize all arguments before you create shell statements to be executed.

stateful-process-command-proxy itself has some extensive options built into it that permit you to whitelist and blacklist commands via custom regular expressions. This is one potential way you can mitigate such injection issues.

Unit tests

To run the unit tests go to the root of the project and run the following.

mocha test/all.js