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syslog-ng Open Source Edition 3.30 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng The syslog-ng OSE quick-start guide The syslog-ng OSE configuration file source: Read, receive, and collect log messages
How sources work default-network-drivers: Receive and parse common syslog messages internal: Collecting internal messages file: Collecting messages from text files wildcard-file: Collecting messages from multiple text files linux-audit: Collecting messages from Linux audit logs network: Collecting messages using the RFC3164 protocol (network() driver) nodejs: Receiving JSON messages from nodejs applications mbox: Converting local email messages to log messages osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes pacct: Collecting process accounting logs on Linux program: Receiving messages from external applications python: writing server-style Python sources python-fetcher: writing fetcher-style Python sources snmptrap: Read Net-SNMP traps sun-streams: Collecting messages on Sun Solaris syslog: Collecting messages using the IETF syslog protocol (syslog() driver) system: Collecting the system-specific log messages of a platform systemd-journal: Collecting messages from the systemd-journal system log storage systemd-syslog: Collecting systemd messages using a socket tcp, tcp6, udp, udp6: Collecting messages from remote hosts using the BSD syslog protocol— OBSOLETE unix-stream, unix-dgram: Collecting messages from UNIX domain sockets stdin: Collecting messages from the standard input stream
destination: Forward, send, and store log messages
amqp: Publishing messages using AMQP collectd: sending metrics to collectd elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED) elasticsearch-http: Sending messages to Elasticsearch HTTP Bulk API file: Storing messages in plain-text files graphite: Sending metrics to Graphite Sending logs to Graylog hdfs: Storing messages on the Hadoop Distributed File System (HDFS) Posting messages over HTTP http: Posting messages over HTTP without Java kafka: Publishing messages to Apache Kafka (Java implementation) kafka: Publishing messages to Apache Kafka (C implementation, using the librdkafka client) loggly: Using Loggly logmatic: Using Logmatic.io mongodb: Storing messages in a MongoDB database network: Sending messages to a remote log server using the RFC3164 protocol (network() driver) osquery: Sending log messages to osquery's syslog table pipe: Sending messages to named pipes program: Sending messages to external applications pseudofile() python: writing custom Python destinations redis: Storing name-value pairs in Redis riemann: Monitoring your data with Riemann slack: Sending alerts and notifications to a Slack channel smtp: Generating SMTP messages (email) from logs snmp: Sending SNMP traps Splunk: Sending log messages to Splunk sql: Storing messages in an SQL database stomp: Publishing messages using STOMP Sumo Logic destinations: sumologic-http() and sumologic-syslog() syslog: Sending messages to a remote logserver using the IETF-syslog protocol syslog-ng(): Forward logs to another syslog-ng node tcp, tcp6, udp, udp6: Sending messages to a remote log server using the legacy BSD-syslog protocol (tcp(), udp() drivers) Telegram: Sending messages to Telegram unix-stream, unix-dgram: Sending messages to UNIX domain sockets usertty: Sending messages to a user terminal: usertty() destination Write your own custom destination in Java or Python Client-side failover
log: Filter and route log messages using log paths, flags, and filters Global options of syslog-ng OSE TLS-encrypted message transfer template and rewrite: Format, modify, and manipulate log messages parser: Parse and segment structured messages db-parser: Process message content with a pattern database (patterndb) Correlating log messages Enriching log messages with external data Statistics of syslog-ng Multithreading and scaling in syslog-ng OSE Troubleshooting syslog-ng Best practices and examples The syslog-ng manual pages Creative Commons Attribution Non-commercial No Derivatives (by-nc-nd) License Glossary

Configuring log rotation

The syslog-ng OSE application does not rotate logs by itself. To use syslog-ng OSE for log rotation, consider the following approaches:

Use logrotate together with syslog-ng OSE:
  • It is ideal for workstations or when processing fewer logs.

  • It is included in most distributions by default.

  • Less scripting is required, only logrotate has to be configured correctly.

  • Requires frequent restart (syslog-ng OSE must be reloaded/restarted when the files are rotated). After rotating the log files, reload syslog-ng OSE using the syslog-ng-ctl reload command, or use another method to send a SIGHUP to syslog-ng OSE.

  • The statistics collected by syslog-ng OSE, and the correlation information gathered with Pattern Database, are lost with each restart.

Separate incoming logs based on time, host or other information:
  • It is ideal for central log servers, where regular restart of syslog-ng OSE is unfavorable.

  • Requires shell scripts or cron jobs to remove old logs.

  • It can be done by using macros in the destination name (in the filename, directory name, or the database table name). (For details on using macros, see Templates and macros.)

Example: File destination for log rotation

This sample file destination configuration stores incoming logs in files that are named based on the current year, month and day, and places these files in directories that are named based on the hostname:

destination d_sorted {
    file(
        "/var/log/remote/${HOST}/${YEAR}_${MONTH}_${DAY}.log"
        create-dirs(yes)
    );
};
Example: Command for cron for log rotation

This sample command for cron removes files older than two weeks from the /var/log/remote directory:

find /var/log/remote/ -daystart -mtime +14 -type f -exec rm {} \;

Load balancing logs between multiple destinations

These sections describe a method of load balancing logs between multiple syslog-ng Open Source Edition (syslog-ng OSE) destinations. The first subsection describes the round robin load balancing method based on the R_MSEC macro of syslog-ng OSE, while the second subsection describes a configuration generator that you can use as an alternative to using the example configuration described in the first subsection.

For more information about the R_MSEC macro and further macros of syslog-ng OSE, see Macros of syslog-ng OSE.

Topics:

Load balancing with a round robin load balancing method based on the R_MSEC macro of syslog-ng OSE

This section describes a round robin load balancing method based on the R_MSEC macro of syslog-ng Open Source Edition (syslog-ng OSE) to load balance your logs between multiple syslog-ng OSE destinations.

TIP: If R_MSEC is not precise enough, you can replace it with R_USEC (which uses microseconds instead of milliseconds).

For more information about the R_MSEC macro and further macros of syslog-ng OSE, see Macros of syslog-ng OSE.

Example: round robin load balancing between multiple destinations

The following example is a round-robin load balancing method, based on syslog-ng OSE's R_MSEC macro.

destination d_lb_network { 
  channel { 
    channel { 
      filter { 
      "0" == "$(% ${R_MSEC} 2)" 
      }; 
      destination { 
        network("myhost1" 
          disk-buffer(mem-buf-length(10000) disk-buf-size(2000000))); 
      }; 
      flags(final); 
    }; 
 
    channel { 
    filter { 
    "1" == "$(% ${R_MSEC} 2)" 
    }; 

    destination { 
      network("myhost2" 
        disk-buffer(mem-buf-length(10000) disk-buf-size(2000000))); 
    }; 
    flags(final); 
    }; 
  }; 
}; 

The filter {" <return value >" == "$(% ${R_MSEC} 2)"}; code snippets (in bold) serve as the basis of the method. This filter separates incoming log messages' timestamp values based on the R_MSEC macro, using a division with remainder method, and distributes the log messages equally between two destinations based on the return value (in this case, 0 or 1).

If you need a file instead of a network destination, replace the network destination with the file in the example (and use the same analogy for any other syslog-ng OSE destinations).

For an alternative method to use the round robin load balancing method based on the R_MSEC macro, see Configuration generator for the load balancing method based on MSEC hashing.

Configuration generator for the load balancing method based on MSEC hashing

This section describes a configuration generator for the load balancing method based on MSEC hashing to load balance your logs between multiple syslog-ng Open Source Edition (syslog-ng OSE) destinations.

Caution:

Consider that network-load-balancer() is not a destination, only a script that generates the example configuration described in Load balancing with a round robin load balancing method based on the R_MSEC macro of syslog-ng OSE .

Also consider that the configuration generator script may change incompatibly in the future. As a result, One Identity does not officially support using this script, and recommends that you only use this script at your own risk.

As an alternative to using the example configuration described in Load balancing with a round robin load balancing method based on the R_MSEC macro of syslog-ng OSE , a configuration generator script is also available in syslog-ng OSE:

destination d_lb {network-load-balancer(targets(myhost1 myhost2 myhost3))};

Where destinations share the same configuration except for the destination address, balancing is based on MSEC hashing.

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