syslog-ng Open Source Edition 3.25 - Administration Guide

Modules in syslog-ng OSE

The syslog-ng OSE application is modular, to increase its flexibility and also to simplify the development of additional modules. Most of the functionality of syslog-ng OSE is in separate modules. That way it becomes also possible to finetune the resource requirements of syslog-ng OSE, for example, by loading only the modules that are actually used in the configuration, or simply omitting modules that are not used but require large amount of memory.

Each module contains one or more plugins, which add some functionality to syslog-ng OSE, for example, a destination or a source driver.

• To display the list of available modules, execute the syslog-ng --version command.

• To the description of the available modules, execute the syslog-ng --module-registry command.

• To customize which modules are loaded automatically when syslog-ng OSE is started, use the --default-modules command-line option of syslog-ng OSE.

• To request loading a module from the syslog-ng OSE configuration file, see Loading modules.

For details on the command-line parameters of syslog-ng OSE mentioned in the previous list, see the syslog-ng OSE man page at The syslog-ng manual page.

Loading modules

The syslog-ng Open Source Edition application loads every available module during startup.

To load a module that is not loaded automatically, include the following statement in the syslog-ng OSE configuration file:

@module <module-name>

Note the following points about the @module statement:

• The @module statement is a top-level statement, that is, it cannot be nested into any other statement. Usually it is used immediately after the @version statement.

• Every @module statement loads a single module: loading multiple modules requires a separate @module statement for every module.

• In the configuration file, the @module statement of a module must be earlier than the module is used.

@define autoload-compiled-modules 0

Use the @requires statement to ensure that the specified module is loaded

To ensure that a module is loaded, include the following statement in the syslog-ng OSE configuration file or the external files included in the configuration file:

@requires <module-name>

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 following command lists the contexts that the utility supports. Currently sources and destinations are supported.

syslog-ng-cfg-db.py

To list the available drivers of a context, use the following command

syslog-ng-cfg-db.py -c <source|destination>

To list the available options of a specific driver, specify 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 that the script caches the list of the options, so if you want to rebuild the database, you have to use the -r option.

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 like Graphviz can use. The package includes a Python script to convert the exported JSON 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.