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7.2.4. Elasticsearch2 destination options

The elasticsearch2 destination can directly send log messages to Elasticsearch, allowing you to search and analyze your data in real time, and visualize it with Kibana. The elasticsearch2 destination has the following options.

Required options: 

The following options are required: index(), type(). In node mode, either the cluster() or the resource() option is required as well. Note that to use elasticsearch2, you must add the following lines to the beginning of your syslog-ng PE configuration:

@module mod-java
@include "scl.conf"

client-lib-dir()

Type: string
Default: The syslog-ng PE module directory: /opt/syslog-ng/lib/syslog-ng/java-modules/

Description: The list of the paths where the required Java classes are located. For example, class-path("/opt/syslog-ng/lib/syslog-ng/java-modules/:/opt/my-java-libraries/libs/"). If you set this option multiple times in your syslog-ng PE configuration (for example, because you have multiple Java-based destinations), syslog-ng PE will merge every available paths to a single list.

Description: Include the path to the directory where you copied the required libraries (see Procedure 7.2.1, Prerequisites), for example, client_lib_dir(/user/share/elasticsearch-2.2.0/lib).

client-mode()

Type: transport | node
Default: node

Description: Specifies the client mode used to connect to the Elasticsearch server, for example, client-mode("node").

  • Transport mode. The syslog-ng PE application uses the transport client API of Elasticsearch, and uses the server(), port(), and cluster() options from the syslog-ng PE configuration file.

  • Node mode. The syslog-ng PE application acts as an Elasticsearch node (client no-data), using the node client API of Elasticsearch. Further options for the node can be describe in an Elasticsearch configuration file specified in the resource() option.

    Note

    In Node mode, it is required to define the home of the elasticsearch installation with the path.home parameter in the .yml file. For example: path.home: /usr/share/elasticsearch.

cluster()

Type: string
Default: N/A

Description: Specifies the name or the Elasticsearch cluster, for example, cluster("my-elasticsearch-cluster"). Optionally, you can specify the name of the cluster in the Elasticsearch resource file. For details, see Section resource().

cluster-url()

Type: string
Default: N/A

Description: Specifies the URL or the Elasticsearch cluster, for example, cluster-url("http://192.168.10.10:9200")"). Note that this option works only in HTTP mode: client_mode(http)

concurrent-requests()

Type: number
Default: 0

Description: The number of concurrent (simultaneous) requests that syslog-ng PE sends to the Elasticsearch server. Set this option to 1 or higher to increase performance. When using the concurrent-requests() option, make sure that the flush-limit() option is higher than one, otherwise it will not have any noticeable effect. For details, see Section flush-limit().

Warning

Hazard of data loss! Using the concurrent-requests() option increases the number of messages lost in case the Elasticsearch server becomes unaccessible.

custom-id()

Type: template or template function
Default: N/A

Description: Use this option to specify a custom ID for the records inserted into Elasticsearch. If this option is not set, the Elasticsearch server automatically generates and ID for the message. For example: custom_id(${UNIQID}) (Note that to use the ${UNIQID} macro, the use-uniqid() global option must be enabled. For details, see Section use-uniqid().)

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 PE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng PE 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 PE 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 PE will look for or create disk-buffer files in their old location. To ensure that syslog-ng PE 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 7.5. 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")
            )
        );
};

flush-limit()

Type: number
Default: 5000

Description: The number of messages that syslog-ng PE sends to the Elasticsearch server in a single batch.

  • If flush-limit is set to 1: syslog-ng PE sends the message reliably: it sends a message to Elasticsearch, then waits for a reply from Elasticsearch. In case of failure, syslog-ng PE repeats sending the message, as set in the retries() parameter. If sending the message fails for retries() times, syslog-ng PE drops the message.

    This method ensures reliable message transfer, but is slow (about 1000 messages/second).

  • If flush-limit is higher than 1: syslog-ng PE sends messages in a batch, and receives the response asynchronously. In case of a problem, syslog-ng PE cannot resend the messages.

    This method is relatively fast (depending on the size of flush-limit, about 8000 messages/second), but the transfer is not reliable. In transport mode, over 5000-30000 messages can be lost before syslog-ng PE recognizes the error. In node mode, about 1000 messages can be lost.

  • If concurrent-requests is higher than 1, syslog-ng PE can send multiple batches simultaneously, increasing performance (and also the number of messages that can be lost in case of an error). For details, see Section concurrent-requests().

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.

index()

Type: string
Default: N/A

Description: Name of the Elasticsearch index to store the log messages. You can use macros and templates as well. For example, index("syslog-ng_${YEAR}.${MONTH}.${DAY}").

jvm-options()

Type: list
Default: N/A

Description: Specify the Java Virtual Machine (JVM) settings of your Java destination from the syslog-ng PE configuration file.

For example:

jvm-options("-Xss1M -XX:+TraceClassLoading")

You can set this option only as a global option, by adding it to the options statement of the syslog-ng configuration file.

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 PE cannot convert some data to the specified type. By default, syslog-ng PE 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 PE.

  • 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.

port()

Type: number
Default: 9300

Description: The port number of the Elasticsearch server. This option is used only in transport mode: client-mode("transport")

retries()

Type: number (of attempts)
Default: 3

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

resource()

Type: string
Default: N/A

Description: The list of Elasticsearch resources to load, separated by semicolons. For example, resource("/home/user/elasticsearch/elasticsearch.yml;/home/user/elasticsearch/elasticsearch2.yml").

server()

Type: list of hostnames
Default: 127.0.0.1

Description: Specifies the hostname or IP address of the Elasticsearch server. When specifying an IP address, IPv4 (for example, 192.168.0.1) or IPv6 (for example, [::1]) can be used as well. When specifying multiple addresses, use space to separate the addresses, for example, server("127.0.0.1 remote-server-hostname1 remote-server-hostname2")

This option is used only in transport mode: client_mode("transport")

In version 7.0.3 and newer, you can list multiple servers in HTTP and HTTPS mode in the cluster_url() and server() options. The syslog-ng PE application will use these destination servers in load-balancing fashion. Note that load-balancing is handled by an external library (Jest), syslog-ng PE does not have any direct influence on it.

For example:

destination d_elasticsearch {
  elasticsearch2(
    client-lib-dir("/usr/share/elasticsearch/lib/")
    index("syslog-${YEAR}.${MONTH}.${DAY}")
    type("syslog")
    time-zone("UTC")
    client_mode("http")
    server("node01 node02")
    port(9200)
  );
};

skip-cluster-health-check()

Type: yes|no
Default: no

Description: By default, when connecting to an Elasticsearch cluster, syslog-ng PE checks the state of the cluster. If the primary shards of the cluster are not active, syslog-ng PE will not send messages, but wait for them to become active. To disable this health check and send the messages to Elasticsearch anyway, use the skip-cluster-health-check(yes) option in your configuration.

template()

Type: template or template function
Default: $(format-json --scope rfc5424 --exclude DATE --key ISODATE @timestamp=${ISODATE})

Description: The message as sent to the Elasticsearch server. Typically, you will want to use the command-line notation of the format-json template function.

To add a @timestamp field to the message, for example, to use with Kibana, include the @timestamp=${ISODATE} expression in the template. For example: template($(format-json --scope rfc5424 --exclude DATE --key ISODATE @timestamp=${ISODATE}))

For details on formatting messages in JSON format, see Section format-json.

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.

time-zone()

Type: name of the timezone, or the timezone offset
Default: unspecified

Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see Section 11.1.3, Date-related macros.

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.

Version 7.0.3 and newer of syslog-ng PE automatically converts the timestamp (date) of the message to UTC, as needed by Elasticsearch and Kibana.

ts-format()

Type: rfc3164, bsd, rfc3339, iso
Default: rfc3164

Description: Override the global timestamp format (set in the global ts-format() parameter) for the specific destination. For details, see Section ts-format().

type()

Type: string
Default: N/A

Description: The type of the index. For example, type("test").