Modules system

A PM2 module is basically a NPM module. But this time it's not a library, but a process that will be run with PM2.

Internally it embed the NPM install procedure. So a PM2 module will be published to NPM and installed from NPM.

Basics

$ pm2 install module-probe
$ pm2 uninstall module-probe

Configuration

$ pm2 set <key> <value>
$ pm2 unset <key>

The key will become an environment variable accesible inside the module

E.g.

$ pm2 set pmx_timeout value

console.log(process.env.pmx_timeout);

Writing a module

THE API IS STILL UNDER INSPECTION

A module is a classic NPM module that contains at least these files:

package.json with all dependencies needed to run this module and the app to be run
index.js a script that init the module and do whatever you need

Publishing a module consist of doing:

$ npm publish

Development workflow

A workflow is available to easily develop new modules:

$ pm2 install .
$ pm2 logs
$ pm2 uninstall .

Every time an update is made the module will be automatically restarted
Use pm2 logs to see how your app behaves
To debug what is send to pm2 just set the variable

process.env.MODULE_DEBUG = true;

Pre flight checks

in the package.json this must be present in order to launch the app:

  [...]
  "apps" : [{
    "script" : "probe.js"
  }]
  [...]

Here is a boilerplate for the main file that will be runned:

var pmx     = require('pmx');

// Load confjs file and init module as PM2 module
var conf    = pmx.loadConfig();

internals.pid allows you to monitor a specific PID instead of the PID of the current process.

internals.errors|latency|versioning|show_module_meta allows you to show or hide panel in the keymetrics dashboard.

internals.name|comment allows you to display some metadata in keymetrics

Internals

Start

1- When a plugin is installed, it does an npm install and move it to .pm2/node_modules/module-name 1- Then the package.json is started with watch option, forced name (= name folder) and started as module

-> pm2_env.pmx_module flag is set to true. Allows to differenciate it from other classic processes

loadConfig()

1- send conf.internals to PM2 with msg type axm:option:configuration 1- Attach this data to pm2_env.axm_options

1- pm2_env.axm_options for the values of the probes

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