Logs

Application Logs

Once an application is started with PM2 you can consult and manage logs easily.

Log files are located in the folder $HOME/.pm2/logs.

Log Views

To display application’s log you can use the command pm2 logs

❯ pm2 logs -h

  Usage: logs [options] [id|name|namespace]

  stream logs file. Default stream all logs

  Options:

    --json                json log output
    --format              formated log output
    --raw                 raw output
    --err                 only shows error output
    --out                 only shows standard output
    --lines <n>           output the last N lines, instead of the last 15 by default
    --timestamp [format]  add timestamps (default format YYYY-MM-DD-HH:mm:ss)
    --nostream            print logs without lauching the log stream
    --highlight [value]   highlights the given value
    -h, --help            output usage information

Some important commands:

# Display all apps logs in realtime
pm2 logs

# Display only `api` application logs
pm2 logs api

# Display new logs in json
pm2 logs --json

# Display 1000 lines of api log file
pm2 logs big-api --lines 1000

You can also check logs with the CLI dashboard:

pm2 monit

Log size limit

The module pm2-logrotate automatically rotate and keep all the logs file using a limited space on disk.

To install it:

pm2 install pm2-logrotate

Read more about pm2-logrotate here

Flushing logs

This will empty the current application logs managed by PM2:

pm2 flush

pm2 flush <api> # Clear the logs for the app with name/id matching <api>

Application log options

When starting an application you can specify many options on how

CLI

When running pm2 start app.js [OPTIONS] you can pass any of this options to the CLI:

-l --log [path]              specify filepath to output both out and error logs
-o --output <path>           specify out log file
-e --error <path>            specify error log file
--time                       prefix logs with standard formated timestamp
--log-date-format <format>   prefix logs with custom formated timestamp
--merge-logs                 when running mutiple process with same app name, do not split file by id

Auto prefixing logs with Date

To easily prefix logs of apps you can pass the option --time:

$ pm2 start app.js --time
# Or a running app
$ pm2 restart app --time

Configuration file

Via configuration file you can pass the options:

Field Type Example Description
error_file (string)   error file path (default to $HOME/.pm2/logs/XXXerr.log)
out_file (string)   output file path (default to $HOME/.pm2/logs/XXXout.log)
pid_file (string)   pid file path (default to $HOME/.pm2/pid/app-pm_id.pid)
merge_logs boolean true if set to true, avoid to suffix logs file with the process id
log_date_format (string) “YYYY-MM-DD HH:mm Z” log date format (see log section)

Disabling log suffix

For app in cluster mode (node.js) only; If you want that all instances of a clustered process logs into the same file you can use the option --merge-logs or merge_logs: true

Disable logging

To disable all logs to be written in disk you can set the option out_file and error_file to /dev/null

module.exports = {
  apps : [{
    name: 'Business News Watcher',
    script: 'app.js',
    instances: 1,
    out_file: "/dev/null",
    error_file: "/dev/null"
    cron_restart: '0 0 * * *'
    [...]
  }]
}

You can provide /dev/null or NULL as output of logs (not depending on the platform, they are harcoded string).

Setting up a native logrotate

sudo pm2 logrotate -u user

This will write a basic logrotate configuration to /etc/logrotate.d/pm2-user that will look like this:

/home/user/.pm2/pm2.log /home/user/.pm2/logs/*.log {
        rotate 12
        weekly
        missingok
        notifempty
        compress
        delaycompress
        create 0640 user user
}
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