Apps health monitor and mail notification module for pm2

pm2, pmx, monitor, mail, crash, push, metric, notification, module
npm install pm2-health-custom@1.1.3



This PM2 module is:

  • Monitoring events (like app exit, restart etc.)
  • Monitoring app exceptions
  • Monitoring PMX metrics of your apps and send alerts when value hits treshold
  • Sending mail notifications

With rich config options you can fine-tune monitoring rules.

Installation & Upgrade

pm2 install pm2-health-custom


After installation run pm2 conf to configure module. Alternatively edit module_conf.json file directly (in PM2 home folder).

Minimum required config:

"pm2-health-custom": {
    "smtp": {
        "host": "your-smtp-host",
        "port": 587,
        "from": "your-from-mail", // if not set, user will be used
        "user": "your-smtp-user",   // auth
        "password": "your-smtp-password",   // auth
        "secure": false,
        "disabled": false
    "mailTo": "mail1,mail2"

If any of required properties is not defined, pm2-health-custom will shutdown. You can check error logs for details.

All config options:

  • smtp - SMTP server configuration. If your SMTP doesn't require auth, leave smtp.user empty

  • mailTo - comma separated list of notification receipients

  • replyTo - reply to address (optional)

  • events - list of events to monitor (optional). If not set, all events will be monitored.

Manually triggered events will not send notification.

  • exceptions - if true apps exceptions will be monitored (optional)

  • messages - if true apps custom messages will be monitored (optional). See Custom messages

  • messageExcludeExps - array of regular expressions used to exclude messages (optional). See Filtering custom messages

  • metric - object describing PMX metrics to be monitored (optional). See Metrics monitoring

  • metricIntervalS - how often PMX metrics will be tested in seconds (optional). If not set, 60 seconds is used

  • aliveTimeoutS - alive watchdog timeout interal in seconds. If not set watchdog function is off. See Process alive watchdog

  • addLogs - if true app logs will be added as mail attachement (optional)

  • appsExcluded - array of app names to exclude from monitoring (optional)

  • appsIncluded - array of app names to include, if set appsExcluded is ignored (optional)

  • webConfig - if set, some of the config settings can be downloaded from given url (optional). See Web config

  • debugLogEnabled - if true debug log is enabled, by default is false (optional)

  • batchPeriodM - enables message batching and sets batching period (optional). See Message batching

  • batchMaxMessages - max. messages in batch (optional). See Message batching

Metrics monitoring

pm2-health-custom can monitor any PMX metrics defined in your apps.

To configure rules of alerting, setup metric section in module config file.

"metric": {
    "metric name": {
        "target": 0,
        "op": ">",
        "ifChanged": true,
        "noNotify": true,
        "noHistory": true,
        "exclude": false
    "metric 2": {
  • metric name - name of metric defined in one of your apps

  • target - target numeric value

  • op - operator to compare metric value and target. Can be one of: <, >, =, <=, >=, !=

  • ifChanged - if true, alert will trigger only if current metric value is different from last recorded value (optional)

  • noNotify - if true, no alerts will be send (optional)

  • noHistory - if true, metric value history won't be stored (optional)

  • exclude - if true, metric will be complettely excluded from monitoring (optional)

  • direct - if true, metric value won't be converted to number (optional)

By default, cpu and memory metrics are added.

Learn how to define PMX metrics in your apps here:

Custom messages

On top of standard PM2 events, you can monitor custom messages sent from your apps.

To send message from your app use:

    type: "process:msg",    
    data: {    
  • type - must be process:msg

  • data - object containing additional data (optional).

Filtering custom messages

You can exclude some of the messages based on their data content:

  1. Add regular expression to list in messageExcludeExp config property
  2. data (converted to JSON string) will be tested with this all expressions in the list
  3. If any test is positive, message will be excluded


You wish to monitor slow operations in your app, so you send custom messages like so:

function slow(operation, duration) {
    process.send({ type: "process:msg", data: { operation, duration }});

You know that backup and restore operations are always slow and wish to exclude them, but still get other slow operations.

Set config to:

"messageExcludeExps": [
    "\"operation\": \"(backup|restore)\""

Remember to escape regex string to JSON string

Process alive watchdog

Alive watchdog (added in 1.9.0) can observe alive messages from processes.

To use functionallity your process has to send periodically process:msg signal as such:

    type: "process:msg",    
    data: "alive"

In addition config parameter aliveTimeoutS must be added. If alive message won't be received within aliveTimeoutS (seconds), alert will be send.

aliveTimeoutS must be lower than interval of sending process:alive signal.

After first alert, following test is done every 10 minues for 6 consecutive times, after wich alerting stops, assuming process is permanetly closed.

Web config

Web config (added in 1.7) allows you to fetch some of the config settings from web url.

Sample config:

    "webConfig": {
        "url": "url of JSON file",
        "auth": {
            "user": "...",
            "password": "..."
        "fetchIntervalM": 10

Url must return UTF-8 JSON with config properties.

Only following properties can be used: events, metric, exceptions, messages, messageExcludeExps, appsExcluded, metricIntervalS, addLogs, batchPeriodM, batchMaxMessages

Message batching

Feature added in (1.11) allows to merge multiple messages over period of time and send them as single message.

This can be used to limit number of messages sent (prevent spam).

To enable please set following properties in config section:

  • batchPeriodM - period (in minutes) to batch, if not set batching is not enabled
  • batchMaxMessages - max. number of messages in batch (optional)

Batch message will be send after batchPeriodM elapses or if number of messages collected are greater than batchMaxMessages.

Priority messages (as exceptions etc.) are not batched and sent immediatelly.

It's advised to set batchMaxMessages to prevent huge messages.

Batching settings can be changed by web config.

Hold notifications temporarily

To hold mail notification: pm2 trigger pm2-health-custom hold 30

Notifications will restart automatically after 30 minutes.

To unhold immediatelly: pm2 trigger pm2-health-custom unheld

All monitoring processes continues, just mail notification is held

Mail template

Mail uses HTML format. To adjust template, you can edit Template.html

<!-- body --> will be exchanged with actual message body.

<!-- timeStamp --> will be exchanged with event timestamp (UTC).

pm2-health-custom update will override your Template.html, so keep backup 😊

Testing mail

To send test mail: pm2 trigger pm2-health-custom mail


pm2-health-custom is written using TypeScript 2.6.1+ with es2017 target.

es2017 is supported by Node 8+. If you need to use ealier version, build solution using es5 or es6 target.

Solution includes VS Code settings for build and debug.