syslog-ng Open Source Edition 3.16 - Administration Guide

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 OSE configuration:

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

client-lib-dir()

Type:	string
Default:	The syslog-ng OSE 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 OSE configuration (for example, because you have multiple Java-based destinations), syslog-ng OSE will merge every available paths to a single list.

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

client-mode()

Type:	http \| https \| transport \| node \| searchguard
Default:	node

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

HTTP mode

The syslog-ng OSE application sends messages over HTTP using the REST API of Elasticsearch, and uses the cluster-url() and cluster() options from the syslog-ng OSE configuration file. In HTTP mode, syslog-ng OSE elasticsearch2 driver can send log messages to every Elasticsearch version, including 1.x-6.x. Note that HTTP mode is available in syslog-ng OSE version 3.8 and newer.

In version 3.10 and newer, you can list multiple servers in HTTP and HTTPS mode in the cluster-url() and server() options. The syslog-ng OSE application will use these destination servers in load-balancing fashion. Note that load-balancing is handled by an external library (Jest), syslog-ng OSE does not have any direct influence on it.
HTTPS mode

The syslog-ng OSE application sends messages over an encrypted and optionally authenticated HTTPS channel using the REST API of Elasticsearch, and uses the cluster-url() and cluster() options from the syslog-ng OSE configuration file. In HTTPS mode, syslog-ng OSE elasticsearch2 driver can send log messages to every Elasticsearch version, including 1.x-6.x. Note that HTTPS mode is available in syslog-ng OSE version 3.10 and newer.

This mode supports password-based and certificate-based authentication of the client, and can verify the certificate of the server as well.

In version 3.10 and newer, you can list multiple servers in HTTP and HTTPS mode in the cluster-url() and server() options. The syslog-ng OSE application will use these destination servers in load-balancing fashion. Note that load-balancing is handled by an external library (Jest), syslog-ng OSE does not have any direct influence on it.
Transport mode

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

The syslog-ng OSE 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.
Search Guard mode

Use the Search Guard Elasticsearch plugin to encrypt and authenticate your connections from syslog-ng OSE to Elasticsearch 2.x. For Elasticsearch versions 5.x and newer, use HTTPS mode. For details on configuring Search Guard mode, see Search Guard and syslog-ng OSE.

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 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)

In version 3.10 and newer, you can list multiple servers in HTTP and HTTPS mode in the cluster-url() and server() options. The syslog-ng OSE application will use these destination servers in load-balancing fashion. Note that load-balancing is handled by an external library (Jest), syslog-ng OSE 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")
    cluster-url("http://node01:9200 http://node02:9200")
  );
};

concurrent-requests()

Type:	number
Default:	0

Description: The number of concurrent (simultaneous) requests that syslog-ng OSE 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 flush-limit().

Caution:

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 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:

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.

Caution:

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.

Caution:

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: 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 OSE sends to the Elasticsearch server in a single batch.

If flush-limit is set to 1: syslog-ng OSE sends the message reliably: it sends a message to Elasticsearch, then waits for a reply from Elasticsearch. In case of failure, syslog-ng OSE repeats sending the message, as set in the retries() parameter. If sending the message fails for retries() times, syslog-ng OSE 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 OSE sends messages in a batch, and receives the response asynchronously. In case of a problem, syslog-ng OSE 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 OSE recognizes the error. In node mode, about 1000 messages can be lost.
If concurrent-requests is higher than 1, syslog-ng OSE 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 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.

hook-commands()

Description: This option makes it possible to execute external programs when the relevant driver is initialized or torn down. The hook-commands() can be used with all source and destination drivers with the exception of the usertty() and internal() drivers.

NOTE: The syslog-ng OSE application must be able to start and restart the external program, and have the necessary permissions to do so. For example, if your host is running AppArmor or SELinux, you might have to modify your AppArmor or SELinux configuration to enable syslog-ng OSE to execute external applications.

Using the hook-commands() when syslog-ng OSE starts or stops

To execute an external program when syslog-ng OSE starts or stops, use the following options:

startup()
Type:	string
Default:	N/A
Description: Defines the external program that is executed as syslog-ng OSE starts.

shutdown()
Type:	string
Default:	N/A
Description: Defines the external program that is executed as syslog-ng OSE stops.

Using the hook-commands() when syslog-ng OSE reloads

To execute an external program when the syslog-ng OSE configuration is initiated or torn down, for example, on startup/shutdown or during a syslog-ng OSE reload, use the following options:

setup()
Type:	string
Default:	N/A
Description: Defines an external program that is executed when the syslog-ng OSE configuration is initiated, for example, on startup or during a syslog-ng OSE reload.

teardown()
Type:	string
Default:	N/A
Description: Defines an external program that is executed when the syslog-ng OSE configuration is stopped or torn down, for example, on shutdown or during a syslog-ng OSE reload.

Example: Using the hook-commands() with a network source

In the following example, the hook-commands() is used with the network() driver and it opens an iptables port automatically as syslog-ng OSE is started/stopped.

The assumption in this example is that the LOGCHAIN chain is part of a larger ruleset that routes traffic to it. Whenever the syslog-ng OSE created rule is there, packets can flow, otherwise the port is closed.

source {
   network(transport(udp)
	hook-commands(
          startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
          shutdown("iptables -D LOGCHAIN 1")
        )
     );
};

http-auth-type()

Type:	none \| basic \| clientcert
Default:	none

Description: Determines how syslog-ng OSE authenticates to the Elasticsearch server. Depending on the value of this option, you might have to set other options as well. Possible values:

none: Connect to the Elasticsearch server without authentication.
basic: Use password authentication. Also set the http-auth-type-basic-username and http-auth-type-basic-password options.
clientcert: Use a certificate to authenticate. The certificate must be available in a Java keystore. Also set the java-keystore-filepath and java-keystore-password options.

This option is used only in HTTPS mode: client-mode("https"), and is available in syslog-ng OSE version 3.10 and newer.

Example: HTTPS authentication examples

The following simple examples show the different authentication modes.

Simple password authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("basic")
        http-auth-type-basic-username("example-username")
        http-auth-type-basic-password("example-password")
    );
};

Certificate authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
    );
};

Verify the certificate of the Elasticsearch server without authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("none")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng OSE client and the Elasticsearch server):

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

http-auth-type-basic-password()

Type:	string
Default:	N/A

Description: The password to use for password-authentication on the Elasticsearch server. You must also set the http-auth-type-basic-username option.

This option is used only in HTTPS mode with basic authentication: client-mode("https") and http-auth-type("basic"), and is available in syslog-ng OSE version 3.10 and newer.

Simple password authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("basic")
        http-auth-type-basic-username("example-username")
        http-auth-type-basic-password("example-password")
    );
};

http-auth-type-basic-username()

Type:	string
Default:	N/A

Description: The username to use for password-authentication on the Elasticsearch server. You must also set the http-auth-type-basic-password option.

This option is used only in HTTPS mode with basic authentication: client-mode("https") and http-auth-type("basic"), and is available in syslog-ng OSE version 3.10 and newer.

Simple password authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("basic")
        http-auth-type-basic-username("example-username")
        http-auth-type-basic-password("example-password")
    );
};

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.

java-keystore-filepath()

Type:	string
Default:	N/A

Description: Path to the Java keystore file that stores the certificate that syslog-ng OSE uses to authenticate on the Elasticsearch server. You must also set the java-keystore-password option.

To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:

keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>

This option is used only in HTTPS mode with basic authentication: client-mode("https") and http-auth-type("clientcert"), and is available in syslog-ng OSE version 3.10 and newer.

Certificate authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
    );
};

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

java-keystore-password()

Type:	string
Default:	N/A

Description: The password of the Java keystore file set in the java-keystore-filepath option.

To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:

keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>

This option is used only in HTTPS mode with basic authentication: client-mode("https") and http-auth-type("clientcert"), and is available in syslog-ng OSE version 3.10 and newer.

Certificate authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
    );
};

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

java-truststore-filepath()

Type:	string
Default:	N/A

Description: Path to the Java keystore file that stores the CA certificate that syslog-ng OSE uses to verify the certificate of the Elasticsearch server. You must also set the java-truststore-password option.

If you do not set the java-truststore-filepath option, syslog-ng OSE does accepts any certificate that the Elasticsearch server shows. In this case, the identity of the server is not verified, only the connection is encrypted.

To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:

keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>

This option is used only in HTTPS mode: client-mode("https"), and is available in syslog-ng OSE version 3.10 and newer.

Verify the certificate of the Elasticsearch server without authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("none")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

java-truststore-password()

Type:	string
Default:	N/A

Description: The password of the Java truststore file set in the java-truststore-filepath option.

To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:

keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>

This option is used only in HTTPS mode: client-mode("https"), and is available in syslog-ng OSE version 3.10 and newer.

Verify the certificate of the Elasticsearch server without authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("none")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

jvm-options()

Type:	list
Default:	N/A

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

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 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.

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")

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 OSE checks the state of the cluster. If the primary shards of the cluster are not active, syslog-ng OSE 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 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 Date-related macros.

The timezone can be specified by using the name, 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 3.10 and newer of syslog-ng OSE 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 ts-format().

NOTE:

This option applies only to file and file-like destinations. Destinations that use specific protocols (for example, network(), or syslog()) ignore this option. For protocol-like destinations, use a template locally in the destination, or use the proto-template option.

type()

Type:	string
Default:	N/A

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

Example use cases of sending logs to Elasticsearch using syslog-ng

destination: Forward, send, and store log messages > elasticsearch2: Sending logs directly to Elasticsearch and Kibana 2.0 or higher > Example use cases of sending logs to Elasticsearch using syslog-ng

This section aims to give you some practical examples about how to make the most of your Elasticsearch-based logging using syslog-ng. Read the following blog posts to learn how to:

Parse data with syslog-ng, store in Elasticsearch, and analyze with Kibana
Get started on Red Hat Enterprise Linux / CentOS using Elasticsearch 6 and syslog-ng
Send netdata metrics through syslog-ng to Elasticsearch
Visualize your data using:
- heat maps
  
  This example uses the GeoIP2 parser. For details about the GeoIP2 parser, see Looking up GeoIP2 data from IP addresses.
- time lapse videos

file: Storing messages in plain-text files

destination: Forward, send, and store log messages > file: Storing messages in plain-text files

The file driver is one of the most important destination drivers in syslog-ng. It allows to output messages to the specified text file, or to a set of files.

The destination filename may include macros which get expanded when the message is written, thus a simple file() driver may create several files: for example, syslog-ng OSE can store the messages of client hosts in a separate file for each host. For more information on available macros see Macros of syslog-ng OSE.

If the expanded filename refers to a directory which does not exist, it will be created depending on the create-dirs() setting (both global and a per destination option).

The file() has a single required parameter that specifies the filename that stores the log messages. For the list of available optional parameters, see file() destination options.

Declaration:

file(filename options());

Example: Using the file() driver

destination d_file { file("/var/log/messages"); };

Example: Using the file() driver with macros in the file name and a template for the message

destination d_file {
    file("/var/log/${YEAR}.${MONTH}.${DAY}/messages"
         template("${HOUR}:${MIN}:${SEC} ${TZ} ${HOST} [${LEVEL}] ${MESSAGE}\n")
         template-escape(no));
};

NOTE:

When using this destination, update the configuration of your log rotation program to rotate these files. Otherwise, the log files can become very large.

Also, after rotating the log files, reload syslog-ng OSE using the syslog-ng-ctl reload command, or use another method to send a SIGHUP to syslog-ng OSE.

Caution:

Since the state of each created file must be tracked by syslog-ng, it consumes some memory for each file. If no new messages are written to a file within 60 seconds (controlled by the time-reap() global option), it is closed, and its state is freed.

Exploiting this, a DoS attack can be mounted against the system. If the number of possible destination files and its needed memory is more than the amount available on the syslog-ng server.

The most suspicious macro is ${PROGRAM}, where the number of possible variations is rather high. Do not use the ${PROGRAM} macro in insecure environments.

file() destination options

destination: Forward, send, and store log messages > file: Storing messages in plain-text files > file() destination options

The file() driver outputs messages to the specified text file, or to a set of files. The file() destination has the following options:

Caution:

When creating several thousands separate log files, syslog-ng might not be able to open the required number of files. This might happen for example when using the ${HOST} macro in the filename while receiving messages from a large number of hosts. To overcome this problem, adjust the --fd-limit command-line parameter of syslog-ng or the global ulimit parameter of your host. For setting the --fd-limit command-line parameter of syslog-ng see the The syslog-ng manual page manual page. For setting the ulimit parameter of the host, see the documentation of your operating system.

create-dirs()

Type:	yes or no
Default:	no

Description: Enable creating non-existing directories.

dir-group()

Type:	string
Default:	Use the global settings

Description: The group of the directories created by syslog-ng. To preserve the original properties of an existing directory, use the option without specifying an attribute: dir-group().

dir-owner()

Type:	string
Default:	Use the global settings

Description: The owner of the directories created by syslog-ng. To preserve the original properties of an existing directory, use the option without specifying an attribute: dir-owner().

Starting with version 3.16, the default value of this option is -1, so syslog-ng OSE does not change the ownership, unless explicitly configured to do so.

dir-perm()

Type:	number
Default:	Use the global settings

Description: The permission mask of directories created by syslog-ng. Log directories are only created if a file after macro expansion refers to a non-existing directory, and directory creation is enabled (see also the create-dirs() option). For octal numbers prefix the number with 0, for example use 0755 for rwxr-xr-x.

To preserve the original properties of an existing directory, use the option without specifying an attribute: dir-perm(). Note that when creating a new directory without specifying attributes for dir-perm(), the default permission of the directories is masked with the umask of the parent process (typically 0022).

disk-buffer()

reliable()

Type:

yes|no

Default:

Caution:

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.

Caution:

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

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: 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")
        )
    );
};

flags()

Type:	no-multi-line, syslog-protocol, threaded
Default:	empty set

Description: Flags influence the behavior of the destination driver.

no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line.
syslog-protocol: The syslog-protocol flag instructs the driver to format the messages according to the new IETF syslog protocol standard (RFC5424), but without the frame header. If this flag is enabled, macros used for the message have effect only for the text of the message, the message header is formatted to the new standard. Note that this flag is not needed for the syslog driver, and that the syslog driver automatically adds the frame header to the messages.
threaded: The threaded flag enables multithreading for the destination. For details on multithreading, see Multithreading and scaling in syslog-ng OSE.

NOTE:
The file destination uses multiple threads only if the destination filename contains macros.

flush-lines()

Type:	number
Default:	Use global setting.

Description: Specifies how many lines are flushed to a destination at a time. The syslog-ng OSE application waits for this number of lines to accumulate and sends them off in a single batch. Increasing this number increases throughput as more messages are sent in a single batch, but also increases message latency.

The syslog-ng OSE application flushes the messages if it has sent flush-lines() number of messages, or the queue became empty. If you stop or reload syslog-ng OSE or in case of network sources, the connection with the client is closed, syslog-ng OSE automatically sends the unsent messages to the destination.

For optimal performance when sending messages to an syslog-ng OSE server, make sure that the flush-lines() is smaller than the window size set using the log-iw-size() option in the source of your server.

flush-timeout() (DEPRECATED)

Type:	time in milliseconds
Default:	Use global setting.

Description: This is a deprecated option. Specifies the time syslog-ng waits for lines to accumulate in its output buffer. For details, see the flush-lines() option.

frac-digits()

Type:	number
Default:	0

fsync()

Type:	yes or no
Default:	no

Description: Forces an fsync() call on the destination fd after each write. Note: enabling this option may seriously degrade performance.

hook-commands()

Using the hook-commands() when syslog-ng OSE starts or stops

To execute an external program when syslog-ng OSE starts or stops, use the following options:

startup()
Type:	string
Default:	N/A
Description: Defines the external program that is executed as syslog-ng OSE starts.

shutdown()
Type:	string
Default:	N/A
Description: Defines the external program that is executed as syslog-ng OSE stops.

Using the hook-commands() when syslog-ng OSE reloads

To execute an external program when the syslog-ng OSE configuration is initiated or torn down, for example, on startup/shutdown or during a syslog-ng OSE reload, use the following options:

setup()
Type:	string
Default:	N/A
Description: Defines an external program that is executed when the syslog-ng OSE configuration is initiated, for example, on startup or during a syslog-ng OSE reload.

teardown()
Type:	string
Default:	N/A
Description: Defines an external program that is executed when the syslog-ng OSE configuration is stopped or torn down, for example, on shutdown or during a syslog-ng OSE reload.

Example: Using the hook-commands() with a network source

In the following example, the hook-commands() is used with the network() driver and it opens an iptables port automatically as syslog-ng OSE is started/stopped.

source {
   network(transport(udp)
	hook-commands(
          startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
          shutdown("iptables -D LOGCHAIN 1")
        )
     );
};

group()

Type:	string
Default:	Use the global settings

Description: Set the group of the created file to the one specified. To preserve the original properties of an existing file, use the option without specifying an attribute: group().

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.

log-fifo-size()

Type:	number
Default:	Use global setting.

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

mark-freq()

Accepted values:	number [seconds]
Default:	1200

Description: An alias for the obsolete mark() option, retained for compatibility with syslog-ng version 1.6.x. The number of seconds between two MARK messages. MARK messages are generated when there was no message traffic to inform the receiver that the connection is still alive. If set to zero (0), no MARK messages are sent. The mark-freq() can be set for global option and/or every MARK capable destination driver if mark-mode() is periodical or dst-idle or host-idle. If mark-freq() is not defined in the destination, then the mark-freq() will be inherited from the global options. If the destination uses internal mark-mode(), then the global mark-freq() will be valid (does not matter what mark-freq() set in the destination side).

mark-mode()

Accepted values:

Default:

internal for pipe, program drivers

none for file, unix-dgram, unix-stream drivers

global for syslog, tcp, udp destinations

host-idle for global option

Description: The mark-mode() option can be set for the following destination drivers: file(), program(), unix-dgram(), unix-stream(), network(), pipe(), syslog() and in global option.

internal: When internal mark mode is selected, internal source should be placed in the log path as this mode does not generate mark by itself at the destination. This mode only yields the mark messages from internal source. This is the mode as syslog-ng OSE 3.3 worked. MARK will be generated by internal source if there was NO traffic on local sources:

file(), pipe(), unix-stream(), unix-dgram(), program()
dst-idle: Sends MARK signal if there was NO traffic on destination drivers. MARK signal from internal source will be dropped.

MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().
host-idle: Sends MARK signal if there was NO local message on destination drivers. For example MARK is generated even if messages were received from tcp. MARK signal from internal source will be dropped.

MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().
periodical: Sends MARK signal perodically, regardless of traffic on destination driver. MARK signal from internal source will be dropped.

MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().
none: Destination driver drops all MARK messages. If an explicit mark-mode() is not given to the drivers where none is the default value, then none will be used.
global: Destination driver uses the global mark-mode() setting. Note that setting the global mark-mode() to global causes a syntax error in syslog-ng OSE.

NOTE:

In case of dst-idle, host-idle and periodical, the MARK message will not be written in the destination, if it is not open yet.

Available in syslog-ng OSE 3.4 and later.

overwrite-if-older()

Type:	number (seconds)
Default:	0

Description: If set to a value higher than 0, syslog-ng OSE checks when the file was last modified before starting to write into the file. If the file is older than the specified amount of time (in seconds), then syslog-ng removes the existing file and opens a new file with the same name. In combination with for example the ${WEEKDAY} macro, this can be used for simple log rotation, in case not all history has to be kept. (Note that in this weekly log rotation example if its Monday 00:01, then the file from last Monday is not seven days old, because it was probably last modified shortly before 23:59 last Monday, so it is actually not even six days old. So in this case, set the overwrite-if-older() parameter to a-bit-less-than-six-days, for example, to 518000 seconds.

owner()

Type:	string
Default:	Use the global settings

Description: Set the owner of the created file to the one specified. To preserve the original properties of an existing file, use the option without specifying an attribute: owner().

pad-size()

Type:	number
Default:	0

Description: If set, syslog-ng OSE will pad output messages to the specified size (in bytes). Some operating systems (such as HP-UX) pad all messages to block boundary. This option can be used to specify the block size. (HP-UX uses 2048 bytes).

Caution:

Hazard of data loss! If the size of the incoming message is larger than the previously set pad-size() value, syslog-ng will truncate the message to the specified size. Therefore, all message content above that size will be lost.

perm()

Type:	number
Default:	Use the global settings

Description: The permission mask of the file if it is created by syslog-ng. For octal numbers prefix the number with 0, for example use 0755 for rwxr-xr-x.

To preserve the original properties of an existing file, use the option without specifying an attribute: perm().

suppress()

Type:	seconds
Default:	0 (disabled)

Description: If several identical log messages would be sent to the destination without any other messages between the identical messages (for example, an application repeated an error message ten times), syslog-ng can suppress the repeated messages and send the message only once, followed by the Last message repeated n times. message. The parameter of this option specifies the number of seconds syslog-ng waits for identical messages.

template()

Type:	string
Default:	A format conforming to the default logfile format.

Description: Specifies a template defining the logformat to be used in the destination. Macros are described in Macros of syslog-ng OSE. Please note that for network destinations it might not be appropriate to change the template as it changes the on-wire format of the syslog protocol which might not be tolerated by stock syslog receivers (like syslogd or syslog-ng itself). For network destinations make sure the receiver can cope with the custom format defined.

template-escape()

Type:	yes or no
Default:	no

Description: Turns on escaping for the ', ", and backspace characters in templated output files. This is useful for generating SQL statements and quoting string contents so that parts of the log message are not interpreted as commands to the SQL server.

time-zone()

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

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 ts-format().

NOTE:

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syslog-ng Open Source Edition 3.16 - Administration Guide

Elasticsearch2 destination options

Required options:

client-lib-dir()

client-mode()

HTTP mode

HTTPS mode

Transport mode

Node mode

Search Guard mode

cluster()

cluster-url()

concurrent-requests()

custom-id()

disk-buffer()

Example: Examples for using disk-buffer()

flush-limit()

frac-digits()

hook-commands()

Using the hook-commands() when syslog-ng OSE starts or stops

Using the hook-commands() when syslog-ng OSE reloads

Example: Using the hook-commands() with a network source

http-auth-type()

Example: HTTPS authentication examples

http-auth-type-basic-password()

http-auth-type-basic-username()

index()

java-keystore-filepath()

java-keystore-password()

java-truststore-filepath()

java-truststore-password()

jvm-options()

log-fifo-size()

on-error()

port()

retries()

resource()

server()

skip-cluster-health-check()

template()

throttle()

time-zone()

ts-format()

type()

Example use cases of sending logs to Elasticsearch using syslog-ng

file: Storing messages in plain-text files

Declaration:

Example: Using the file() driver

Example: Using the file() driver with macros in the file name and a template for the message

file() destination options

create-dirs()

dir-group()

dir-owner()

dir-perm()

disk-buffer()

Example: Examples for using disk-buffer()

flags()

flush-lines()

flush-timeout() (DEPRECATED)

frac-digits()

fsync()

hook-commands()

Using the hook-commands() when syslog-ng OSE starts or stops

Using the hook-commands() when syslog-ng OSE reloads

Example: Using the hook-commands() with a network source

group()

local-time-zone()

log-fifo-size()

mark-freq()

mark-mode()

overwrite-if-older()

owner()

pad-size()

perm()

suppress()

template()

template-escape()

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