syslog-ng Open Source Edition 3.22 - Administration Guide

HDFS destination options

The hdfs destination stores the log messages in files on the Hadoop Distributed File System (HDFS). The hdfs destination has the following options.

The following options are required: hdfs-file(), hdfs-uri(). Note that to use hdfs, you must add the following lines to the beginning of your syslog-ng OSE configuration:

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

client-lib-dir()

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.

For the hdfs destination, include the path to the directory where you copied the required libraries (see Prerequisites), for example, client-lib-dir("/opt/syslog-ng/lib/syslog-ng/java-modules/:/opt/hadoop/libs/").

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:

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

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")
        )
    );
};

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()

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.

hdfs-append-enabled()

Description: When hdfs-append-enabled is set to true, syslog-ng OSE will append new data to the end of an already existing HDFS file. Note that in this case, archiving is automatically disabled, and syslog-ng OSE will ignore the hdfs-archive-dir option.

When hdfs-append-enabled is set to false, the syslog-ng OSE application always creates a new file if the previous has been closed. In that case, appending data to existing files is not supported.

When you choose to write data into an existing file, syslog-ng OSE does not extend the filename with a UUID suffix because there is no need to open a new file (a new unique ID would mean opening a new file and writing data into that).

destination d_hdfs_9bf3ff45341643c69bf46bfff940372a {
    hdfs(client-lib-dir(/hdfs-libs)
 hdfs-uri("hdfs://hdp2.syslog-ng.example:8020")
 hdfs-file("/var/testdb_working_dir/$DAY-$HOUR.txt"));
};

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.

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:

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:

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

jvm-options()

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.

destination d_hdfs {
    hdfs(client-lib-dir("/hdfs-libs/lib")
    hdfs-uri("hdfs://hdp-kerberos.syslog-ng.example:8020")
    kerberos-keytab-file("/opt/syslog-ng/etc/hdfs.headless.keytab")
    kerberos-principal("hdfs-hdpkerberos@MYREALM")
    hdfs-file("/var/hdfs/test.log"));
};

destination d_hdfs {
    hdfs(client-lib-dir("/hdfs-libs/lib")
    hdfs-uri("hdfs://hdp-kerberos.syslog-ng.example:8020")
    kerberos-keytab-file("/opt/syslog-ng/etc/hdfs.headless.keytab")
    kerberos-principal("hdfs-hdpkerberos@MYREALM")
    hdfs-file("/var/hdfs/test.log"));
};

log-fifo-size()

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

on-error()

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.

retries()

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.

template()

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.

throttle()

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()

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.

ts-format()

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

Posting messages over HTTP

Version 3.7 of syslog-ng OSE can directly post log messages to web services using the HTTP protocol. Error and status messages received from the HTTP server are forwarded to the internal logs of syslog-ng OSE. The current implementation has the following limitations:

• This destination is only supported on the Linux platform.

• Only HTTP connections are supported, HTTPS is not.

• This destination requires Java. For an http destination that does not use Java, see http: Posting messages over HTTP without Java.

@module mod-java

java(
    class-path("/syslog-ng/install_dir/lib/syslog-ng/java-modules/*.jar")
    class-name("org.syslog_ng.http.HTTPDestination")

    option("url", "http://<server-address>:<port-number>")

);

@module mod-java

destination d_http {
    java(
        class-path("/syslog-ng/install_dir/lib/syslog-ng/java-modules/*.jar")
        class-name("org.syslog_ng.http.HTTPDestination")

        option("url", "http://192.168.1.1:80")
    );
};

log
    { source(s_file); destination(d_http); flags(flow-control); };

HTTP destination options

The http destination of syslog-ng OSE can directly post log messages to web services using the HTTP protocol. The http destination has the following options. Some of these options are directly used by the Java code underlying the http destination, therefore these options must be specified in the following format:

option("<option-name>", "<option-value>")

For example, option("url", "http://<server-address>:<port-number>"). The exact format to use is indicated in the description of the option.

@module mod-java

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.

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:

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:

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

jvm-options()

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()

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

retries()

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.

template()

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.

throttle()

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.

http: Posting messages over HTTP without Java

Version 3.8 of syslog-ng OSE can directly post log messages to web services using the HTTP protocol, without having to use Java. The current implementation has the following limitations:

• Only the PUT and the POST methods are supported.

HTTPS connection, as well as password- and certificate-based authentication is supported.

If the server returns a status code beginning with 4 (for example, 404) to the POST or PUT request, syslog-ng OSE drops the message without trying to resend it.

destination d_https {
    http(
        [...]
        tls(
        ca-file("/<path-to-certificate-directory>/ca-crt.pem")
        ca-dir("/<path-to-certificate-directory>/")
        cert-file("/<path-to-certificate-directory>/server-crt.pem")
        key-file("/<path-to-certificate-directory>/server-key.pem")
            )
        [...]
    );
};

destination d_http {
    http(
        url("<web-service-IP-or-hostname>")
        method("<HTTP-method>")
        user-agent("<USER-AGENT-message-value>")
        user("<username>")
        password("<password>")
    );
};

The driver automatically uses the proxy settings of the host, there is no option to set it in the syslog-ng OSE configuration. Specifically, the driver uses the settings of the http_proxy and https_proxy environment variables.

destination d_http {
    http(
        url("http://127.0.0.1:8000")
        method("PUT")
        user-agent("syslog-ng User Agent")
        user("user")
        password("password")
        headers("HEADER1: header1", "HEADER2: header2")
        body("${ISODATE} ${MESSAGE}")
    );
};

log {
    source(s_file);
    destination(d_http);
    flags(flow-control);
};

You can also use the http() destination to forward log messages to Splunk using syslog-ng OSE.