How to use log4go with configuration file?

Question

I have been trying to use log4go in golang. But I could not find a proper example where log4go configuration properties were used like rotation,maxSize etc to create a logger. Can somebody provide a example? I have referred to many sites.

Answer 1

log4go is not well documented, I found some documentation in the original repository.
If you can, I'd use a different library like logrus, has a better documentation, examples and is actively developed.

Answer 2

The easy way is to use the logConfig xml, for example:

<code>
    <logging>
    <filter enabled="true">
      <tag>stdout</tag>
      <type>console</type>
      <!-- level is (:?FINEST|FINE|DEBUG|TRACE|INFO|WARNING|ERROR) -->
      <level>INFO</level>
      </filter>
      <filter enabled="true">
            <tag>file</tag>
            <type>file</type>
            <level>INFO</level>
            <property name="filename"><log file Path></property>

            <!--
              %T - Time (15:04:05 MST)
              %t - Time (15:04)
              %D - Date (2006/01/02)
              %d - Date (01/02/06)
              %L - Level (FNST, FINE, DEBG, TRAC, WARN, EROR, CRIT)
              %S - Source
              %M - Message
              It ignores unknown format strings (and removes them)
              Recommended: "[%D %T] [%L] (%S) %M"
            -->
            <property name="format">[%D %T] [%L] (%S) %M</property>
            <property name="rotate">true</property> <!-- true enables log rotation, otherwise append -->
            <property name="maxsize">10M</property> <!-- \d+[KMG]? Suffixes are in terms of 2**10 -->
            <property name="maxlines">0K</property> <!-- \d+[KMG]? Suffixes are in terms of thousands -->
            <property name="daily">true</property> <!-- Automatically rotates when a log message is written after midnight -->
            <property name="maxbackup">10</property> <!-- Max backup for logs rotation -->
      </filter>
    </logging>

Personally, I preferred zarolog : https://github.com/rs/zerolog

Answer 3

Here is one example which can have two logs:

{
  "console": {
    "enable": true,
    "level": "ERROR"
  },
  "files": [{
    "enable": true,
    "level": "DEBUG",
    "filename":"./log/sys.log",
    "category": "syslog",
    "pattern": "[%D %T] [%L] (%S) %M",
    "rotate": true,
    "maxsize": "5M",
    "maxlines": "10K",
    "daily": true
  },
    {
      "enable": true,
      "level": "INFO",
      "filename":"./log/market.log",
      "category": "marketlog",
      "pattern": "[%D %T] [%L] (%S) %M",
      "rotate": false,
      "maxsize": "10M",
      "maxlines": "20K",
      "daily": false
    }
  ]
}

usage in code:

log4go.LOGGER("syslog").Info("...")
log4go.LOGGER("marketlog").Debug("...")

the debug calls on marketlog would not be written in this case because the "INFO" level automatically filters it out.