syslog-ng Open Source Edition 3.33 - 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 mqtt() destination: sending messages from a local network to an MQTT broker 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

Listing configuration options

Starting with syslog-ng OSE 3.25, you can use the syslog-ng-cfg-db.py utility to list the available options of configuration objects. For example, you can list all the options that can be set in the file source, and so on.

The syslog-ng-cfg-db.py utility has the following options:

  • The following command lists the contexts that the utility supports.
    syslog-ng-cfg-db.py

    NOTE: Currently, sources and destinations are supported.

  • The following command lists the available drivers of a context:
    syslog-ng-cfg-db.py -c <source|destination>
  • The following command lists the available options of a specific driver and specifies the context and the driver:
    syslog-ng-cfg-db.py -c <source|destination> -d <driver>

    For example, to list the options of the kafka-c() destination driver:

    syslog-ng-cfg-db.py -c destination -d kafka-c

    The output includes the available options of the driver in alphabetical order, and the type of the option. For example:

    destination kafka-c(
        bootstrap-servers/kafka-bootstrap-servers(<string>)
        client-lib-dir(<string>)
        config/option()
        config/option(<string> <arrow> <string-or-number>)
        config/option(<string> <string-or-number>)
        flush-timeout-on-reload(<number>)
        flush-timeout-on-shutdown(<number>)
        frac-digits(<number>)
        key(<string>)
        local-time-zone/time-zone(<string>)
        log-fifo-size(<number>)
        message/template(<string>)
        on-error(<string>)
        persist-name(<string>)
        poll-timeout(<number>)
        properties-file(<path>)
        send-time-zone(<string>)
        sync-send(<yesno>)
        throttle(<number>)
        time-zone(<string>)
        topic(<string>)
        ts-format(<string>)
        workers(<number>)
        config/option(
            <string>(<string-or-number>)
        )
        key(
            <identifier>(<string>)
        )
        message/template(
            <identifier>(<string>)
        )
    )

    NOTE: The script caches the list of the options, so if you want to rebuild the database, you have to use the -r option.


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Visualize the configuration

Starting with syslog-ng OSE 3.25, you can visualize the configuration of a running syslog-ng OSE instance using the syslog-ng-ctl --export-config-graph command. The command walks through the effective configuration, and exports it as a graph into a JSON structure.

The resulting JSON file can be converted into DOT file format that visualization tools (for example, Graphviz) can use. The package includes a Python script to convert the exported JSON file into DOT format: <syslog-ng-installation-directory>/contrib/scripts/config-graph-json-to-dot.py

You can convert the DOT file into PNG or PDF format using external tools.


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Managing complex syslog-ng configurations

The following sections describe some methods that can be useful to simplify the management of large-scale syslog-ng installations.


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Including configuration files

The syslog-ng application supports including external files in its configuration file, so parts of its configuration can be managed separately. To include the contents of a file in the syslog-ng configuration, use the following syntax:

@include "<filename>"

This imports the entire file into the configuration of syslog-ng OSE, at the location of the include statement. The <filename> can be one of the following:

  • A filename, optionally with full path. The filename (not the path) can include UNIX-style wildcard characters (*, ?). When using wildcard characters, syslog-ng OSE will include every matching file. For details on using wildcard characters, see Options of regular expressions.

  • A directory. When including a directory, syslog-ng OSE will try to include every file from the directory, except files beginning with a ~ (tilde) or a . (dot) character. Including a directory is not recursive. The files are included in alphabetic order, first files beginning with uppercase characters, then files beginning with lowercase characters. For example, if the directory contains the a.conf, B. conf, c.conf, D.conf files, they will be included in the following order: B.conf, D. conf, a.conf, c.conf.

When including configuration files, consider the following points:

  • The default path where syslog-ng OSE looks for the file depends on where syslog-ng OSE is installed. The syslog-ng --version command displays this path as Include-Path.

  • Defining an object twice is not allowed, unless you use the @define allow-config-dups 1 definition in the configuration file. If an object is defined twice (for example, the original syslog-ng configuration file and the file imported into this configuration file both define the same option, source, or other object), then the object that is defined later in the configuration file will be effective. For example, if you set a global option at the beginning of the configuration file, and later include a file that defines the same option with a different value, then the option defined in the imported file will be used.

  • Files can be embedded into each other: the included files can contain include statements as well, up to a maximum depth of 15 levels.

  • You cannot include complete configuration files into each other, only configuration snippets can be included. This means that the included file cannot have a @version statement.

  • Include statements can only be used at top level of the configuration file. For example, the following is correct:

    @version: 3.33
    @include "example.conf"

    But the following is not:

    source s_example {
        @include "example.conf"
    };

Caution:

The syslog-ng application will not start if it cannot find a file that is to be included in its configuration. Always double-check the filenames, paths, and access rights when including configuration files, and use the --syntax-only command-line option to check your configuration.


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