7.12.2. mongodb() destination options

The mongodb() driver sends messages to a MongoDB database. MongoDB is a schema-free, document-oriented database.

The mongodb() destination has the following options:

collection()

Type: string
Default: messages

Description: The name of the MongoDB collection where the log messages are stored (collections are similar to SQL tables). Note that the name of the collection must not start with a dollar sign ($), and that it may contain dot (.) characters.

Warning

Hazard of data loss! The syslog-ng OSE application does not verify that the specified collection name does not contain invalid characters. If you specify a collection with an invalid name, the log messages sent to the MongoDB database will be irrevocably lost without any warning.

database() (DEPRECATED)

Type: string
Default: syslog

This option is deprecated and will be removed from syslog-ng OSE. Use the uri() option instead.

Description: The name of the MongoDB database where the log messages are stored. Note that the name of the database must not start with a dollar sign ($) and it cannot contain dot (.) characters.

Warning

Hazard of data loss! The syslog-ng OSE application does not verify that the specified database name does not contain invalid characters. If you specify a database with an invalid name, the log messages sent to the MongoDB database will be irrevocably lost without any warning.

disk-buffer()

Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:

reliable()  
Type: yes|no
Default: no
 

Description: If set to yes, syslog-ng OSE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng OSE crash. This solution provides a slower, but reliable disk-buffer option. It is created and initialized at startup and gradually grows as new messages arrive. If set to no, the normal disk-buffer will be used. This provides a faster, but less reliable disk-buffer option.

Warning

Hazard of data loss! If you change the value of reliable() option when there are messages in the disk-buffer, the messages stored in the disk-buffer will be lost.

dir()  
Type: string
Default: N/A
 

Description: Defines the folder where the disk-buffer files are stored.

Warning

When creating a new dir() option for a disk buffer, or modifying an existing one, make sure you delete the persist file.

syslog-ng OSE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file is not deleted after modifying the dir() option, then following a restart, syslog-ng OSE will look for or create disk-buffer files in their old location. To ensure that syslog-ng OSE uses the new dir() setting, the persist file must not contain any information about the destinations which the disk-buffer file in question belongs to.

disk-buf-size()  
Type: number (bytes)
Default:  
 Description: This is a required option. The maximum size of the disk-buffer in bytes. The minimum value is 1048576 bytes. If you set a smaller value, the minimum value will be used automatically. It replaces the old log-disk-fifo-size() option.
mem-buf-length()  
Type: number (messages)
Default: 10000
 Description: Use this option if the option reliable() is set to no. This option contains the number of messages stored in overflow queue. It replaces the old log-fifo-size() option. It inherits the value of the global log-fifo-size() option if provided. If it is not provided, the default value is 10000 messages. Note that this option will be ignored if the option reliable() is set to yes.
mem-buf-size()  
Type: number (bytes)
Default: 163840000
 Description: Use this option if the option reliable() is set to yes. This option contains the size of the messages in bytes that is used in the memory part of the disk buffer. It replaces the old log-fifo-size() option. It does not inherit the value of the global log-fifo-size() option, even if it is provided. Note that this option will be ignored if the option reliable() is set to no.
qout-size()  
Type: number (messages)
Default: 64
 Description: The number of messages stored in the output buffer of the destination.

Options reliable() and disk-buf-size() are required options.

Example 7.27. Examples for using disk-buffer()

In the following case reliable disk-buffer() is used.

destination d_demo {
    network(
            "127.0.0.1"
            port(3333)
            disk-buffer(
                mem-buf-size(10000)
                disk-buf-size(2000000)
                reliable(yes)
                dir("/tmp/disk-buffer")
            )
        );
};

In the following case normal disk-buffer() is used.

destination d_demo {
    network(
            "127.0.0.1"
            port(3333)
            disk-buffer(
                mem-buf-length(10000)
                disk-buf-size(2000000)
                reliable(no)
                dir("/tmp/disk-buffer")
            )
        );
};

frac-digits()

Type: number
Default: 0

Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received. Note that syslog-ng can add the fractions to non-ISO8601 timestamps as well.

local-time-zone()

Type: name of the timezone, or the timezone offset
Default: The local timezone.

Description: Sets the timezone used when expanding filename and tablename templates.

The timezone can be specified as using the name of the (for example time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format (for example +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.

log-fifo-size()

Type: number
Default: Use global setting.

Description: The number of messages that the output queue can store.

on-error()

Accepted values: drop-message|drop-property|fallback-to-string|silently-drop-message|silently-drop-property|silently-fallback-to-string
Default: Use the global setting (which defaults to drop-message)

Description: Controls what happens when type-casting fails and syslog-ng OSE cannot convert some data to the specified type. By default, syslog-ng OSE drops the entire message and logs the error. Currently the value-pairs() option uses the settings of on-error().

  • drop-message: Drop the entire message and log an error message to the internal() source. This is the default behavior of syslog-ng OSE.

  • drop-property: Omit the affected property (macro, template, or message-field) from the log message and log an error message to the internal() source.

  • fallback-to-string: Convert the property to string and log an error message to the internal() source.

  • silently-drop-message: Drop the entire message silently, without logging the error.

  • silently-drop-property: Omit the affected property (macro, template, or message-field) silently, without logging the error.

  • silently-fallback-to-string: Convert the property to string silently, without logging the error.

password() (DEPRECATED)

Type: string
Default: n/a

This option is deprecated and will be removed from syslog-ng OSE. Use the uri() option instead.

Description: Password of the database user.

path() (DEPRECATED)

Type: string
Default: empty

This option is deprecated and will be removed from syslog-ng OSE. Use the uri() option instead.

Description: If the path() option is set, syslog-ng OSE will connect to the database using the specified UNIX domain socket. Note that you cannot set the path() and the servers() options at the same time.

retries()

Type: number (of attempts)
Default: 3

Description: The number of times syslog-ng OSE attempts to send a message to this destination. If syslog-ng OSE could not send a message, it will try again until the number of attempts reaches retries, then drops the message.

For MongoDB operations, syslog-ng OSE uses a one-minute timeout: if an operation times out, syslog-ng OSE assumes the operation has failed.

safe-mode() (DEPRECATED)

Type: yes or no
Default: yes

This option is deprecated and will be removed from syslog-ng OSE. Use the uri() option instead.

Description: If safe-mode() is enabled, syslog-ng OSE performs an extra check after each insert to verify that the insert succeeded. The insert is successful only if this second check is successful. Note that enabling this option reduces the performance of the driver.

servers() (DEPRECATED)

Type: list of hostname:port pairs
Default: 127.0.0.1:27017

This option is deprecated and will be removed from syslog-ng OSE. Use the uri() option instead.

Description: Specifies the hostname or IP address and the port number of the database server. When specifying an IP address, IPv4 (for example, 192.168.0.1) or IPv6 (for example, [::1]) can be used as well.

To send the messages to a MongoDB replicaset, specify the addresses of the database servers as a comma-separated list, for example: servers(192.168.1.1:27017,192.168.3.3:27017)

For details on how syslog-ng OSE connects the MongoDB server, see Procedure 7.12.1, How syslog-ng OSE connects the MongoDB server.

To connect to the server using a UNIX domain socket, use path option. Note that you cannot set the path() and the servers() options at the same time.

throttle()

Type: number
Default: 0

Description: Sets the maximum number of messages sent to the destination per second. Use this output-rate-limiting functionality only when using disk-buffer as well to avoid the risk of losing messages. Specifying 0 or a lower value sets the output limit to unlimited.

uri()

Type: string
Default: mongodb://127.0.0.1:27017/syslog?wtimeoutMS=60000&socketTimeoutMS=60000&connectTimeoutMS=60000

Description: Available in syslog-ng OSE 3.8 and later. Please refer to the MongoDB URI format documentation for detailed syntax.

username() (DEPRECATED)

Type: string
Default: n/a

This option is deprecated and will be removed from syslog-ng OSE. Use the uri() option instead.

Description: Name of the database user. Note that the mongodb() driver currently does not support TLS-encrypted authentication.

value-pairs()

Type: parameter list of the value-pairs() option
Default:
scope("selected-macros" "nv-pairs")

Description: The value-pairs() option creates structured name-value pairs from the data and metadata of the log message. For details on using value-pairs(), see Section 2.10, Structuring macros, metadata, and other value-pairs.

Note

Empty keys are not logged.

Note

By default, syslog-ng OSE handles every message field as a string. For details on how to send selected fields as other types of data (for example, handle the PID as a number), see Section 2.10.1, Specifying data types in value-pairs.