Configuring log rotation

Available in Informer 2025.2.9 and later.

Informer has built-in log rotation that manages log file size and retention automatically, keeping the server healthy and Elasticsearch uninterrupted. It rotates logs by size and/or date, lets you cap how many archives are kept, and can compress them.

Configuration

Log rotation is off by default. To enable it, set logDestination to file in the Informer config and adjust logFile:

"logDestination": "file",
"logFile": {
  "logDirectory": "logs",
  "maxSize": "20m",
  "maxFiles": "14d",
  "zippedArchive": true,
  "filename": "informer5-%DATE%.log",
  "datePattern": "YYYY-MM-DD",
  "instanceIdVar": "NODE_APP_INSTANCE"
}

When logDestination is stdout (the default), logs go to standard output and all logFile settings are ignored.

Parameters

Parameter	Default	What it does
logDestination	stdout	Set to file to enable log rotation; stdout sends logs to standard output and ignores the settings below.
logDirectory	logs	Subdirectory for log files, relative to the Informer data directory.
maxSize	20m	Size at which a log file rotates. Use a unit suffix (20m, 500k, 2g) directly after the number, or raw bytes as a number (20971520).
maxFiles	14d	How many archives to keep. Use a days suffix (14d, 30d) or a raw count (10 keeps the last 10 files). If unset, nothing is removed.
zippedArchive	true	Whether to gzip rotated logs to .gz.
filename	informer-%DATE%.log	Filename template. Must include %DATE%. In cluster mode the instance ID is appended (for example informer-2025-02-19-0.log).
datePattern	YYYY-MM-DD	Date format for %DATE%, which also sets how often logs rotate: YYYY-MM-DD daily, YYYY-MM-DD-HH hourly, YYYY-MM monthly.
instanceIdVar	NODE_APP_INSTANCE	The environment variable holding the PM2 instance ID in cluster mode, so each worker logs to its own file. PM2 sets NODE_APP_INSTANCE by default; match this to your PM2 instance_var if you customized it. Valid values: NODE_APP_INSTANCE or INSTANCE_ID.