Common Log Formats

This page is a glossary of common log formats that can be parsed with the Tail input plugin.

• Apache Access Log

  Use format apache2 as shown below:

    <source>
        @type tail
        format apache2
        tag apache.access
        path /var/log/apache2/access.log
    </source>

• Apache Error Log

  Use a regular expression. See the format field in the following sample configuration.

    <source>
        @type tail
        format /^\[[^ ]* (?<time>[^\]]*)\] \[(?<level>[^\]]*)\] \[pid (?<pid>[^\]]*)\] \[client (?<client>[^\]]*)\] (?<message>.*)$/
        tag apache.error
        path /var/log/apache2/error.log
    </source>

  Depending on your particular error log format, you may need to adjust the regular expression above. You can test your format using fluentd-ui's in_tail editor or Fluentular.

• Maillog

  Use a regular expression. See the format field in the following sample configuration.

    <source>
        @type tail
        format /^(?<time>[^ ]+) (?<host>[^ ]+) (?<process>[^:]+): (?<message>((?<key>[^ :]+)[ :])? ?((to|from)=<(?<address>[^>]+)>)?.*)$/
        tag postfix.maillog
        path /var/log/maillog
    </source>

• Nginx Access Log

  Use format nginx as shown below:

    <source>
        @type tail
        format nginx
        tag nginx.access
        path /var/log/nginx/access.log
    </source>

• Nginx Error Log

  Use the format* and multiline_flush_interval fields in the following sample configuration. Applications running under Nginx can output multi-line errors including stack traces, so the multiline mode is a good fit.

    <source>
        @type tail
        tag nginx.error
        path /var/log/nginx/error.log
  
        format multiline
        format_firstline /^\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2} \[\w+\] (?<pid>\d+).(?<tid>\d+): /
        format1 /^(?<time>\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2}) \[(?<log_level>\w+)\] (?<pid>\d+).(?<tid>\d+): (?<message>.*)/
        multiline_flush_interval 3s
    </source>

  If you know your error log will only contain single lines, you can use the below simpler configuration with just a format.

    <source>
        @type tail
        format /^(?<time>\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2}) \[(?<log_level>\w+)\] (?<pid>\d+).(?<tid>\d+): (?<message>.*)$/
        tag nginx.error
        path /var/log/nginx/error.log
    </source>

• GlusterFS Logs

  Use the GlusterFS input plugin.

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If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is a open source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.