Modules in syslog-ng Premium Edition (syslog-ng PE)
To increase its flexibility and simplify the development of additional modules, the syslog-ng PE application is modular. The majority of syslog-ng PE's functionality is in separate modules. As a result, it is also possible to fine-tune the resource requirements of syslog-ng PE (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 that add some functionality to syslog-ng PE (for example, a destination or a source driver).
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To display the list of available modules, run the syslog-ng --version command.
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To display the description of the available modules, run the syslog-ng --module-registry command.
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To customize which modules syslog-ng PE automatically loads when syslog-ng PE starts, use the --default-modules command-line option of syslog-ng PE.
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To request loading a module from the syslog-ng PE configuration file, see Loading modules.
For details on the command-line parameters of syslog-ng PE mentioned in the previous list, see the syslog-ng PE man page at The syslog-ng manual page.
Loading modules
The syslog-ng Premium 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 PE configuration file:
@module <module-name>
Note the following points about the @module statement:
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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.
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Every @module statement loads a single module: loading multiple modules requires a separate @module statement for every module.
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In the configuration file, the @module statement of a module must be earlier than the module is used.
NOTE: To disable loading every module automatically, set the autoload-compiled-modules global variable to 0 in your configuration file:
@define autoload-compiled-modules 0
Note that in this case you have to explicitly load the modules you want to use.
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.
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 "<path to filename>"
NOTE: If you enter only the filename, syslog-ng PE will search for the file in the default directory: /opt/syslog-ng/etc. If syslog-ng PE has been installed to a different directory, use the full path instead.
This imports the entire file into the configuration of syslog-ng PE, at the location of the include statement. The <filename> can be one of the following:
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A filename, optionally with full path. The filename (not the path) can include UNIX-style wildcard characters (*, ?). When using wildcard characters, syslog-ng PE will include every matching file. For details on using wildcard characters, see glob.
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A directory. When including a directory, syslog-ng PE 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:
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NOTE: One Identity strongly recommends that you include the scl.conf file in your syslog-ng PE configuration. To include the scl.conf file in your configuration, use the following syntax:
@include "scl.conf"
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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.
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Files can be embedded into each other: the included files can contain include statements as well, up to a maximum depth of 15 levels.
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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.
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Include statements can only be used at top level of the configuration file. For example, the following is correct:
@version: 7.0
@include "example.conf"
But the following is not:
source s_example {
@include "example.conf"
};
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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. |
