pipe() source options

The pipe driver has the following options:

check-hostname()


Type:	boolean (`yes` or `no`)
Default:	Use the global `check-hostname()` option, which defaults to `no`.

Checks that the hostname contains valid characters. Uses the value of the global option if not specified.

create-dirs()


Type:	yes or no
Default:	no

Description: Enable creating non-existing directories when creating files or socket files.

flags()


Type:	assume-utf8, dont-store-legacy-msghdr, empty-lines, expect-hostname, kernel, no-hostname, no-multi-line, no-parse, sanitize-utf8, store-legacy-msghdr, store-raw-message, syslog-protocol, validate-utf8
Default:	empty set

Description: Specifies the log parsing options of the source.

assume-utf8: The assume-utf8 flag assumes that the incoming messages are UTF-8 encoded, but does not verify the encoding. If you explicitly want to validate the UTF-8 encoding of the incoming message, use the validate-utf8 flag.
dont-store-legacy-msghdr: By default, AxoSyslog stores the original incoming header of the log message. This is useful if the original format of a non-syslog-compliant message must be retained (AxoSyslog automatically corrects minor header errors, for example, adds a whitespace before msg in the following message: Jan 22 10:06:11 host program:msg). If you do not want to store the original header of the message, enable the dont-store-legacy-msghdr flag.
empty-lines: Use the empty-lines flag to keep the empty lines of the messages. By default, AxoSyslog removes empty lines automatically.
exit-on-eof: If this flag is set on a source, AxoSyslog stops when an EOF (end of file) is received. Available in version 4.9 and later.
expect-hostname: If the expect-hostname flag is enabled, AxoSyslog will assume that the log message contains a hostname and parse the message accordingly. This is the default behavior for TCP sources. Note that pipe sources use the no-hostname flag by default.
guess-timezone: Attempt to guess the timezone of the message if this information is not available in the message. Works when the incoming message stream is close to real time, and the timezone information is missing from the timestamp.
kernel: The kernel flag makes the source default to the LOG_KERN | LOG_NOTICE priority if not specified otherwise.
no-header: The no-header flag triggers AxoSyslog to parse only the PRI field of incoming messages, and put the rest of the message contents into $MSG.

Its functionality is similar to that of the no-parse flag, except the no-header flag does not skip the PRI field.

Note Essentially, the no-header flag signals AxoSyslog that the syslog header is not present (or does not adhere to the conventions / RFCs), so the entire message (except from the PRI field) is put into $MSG.

Example: using the no-header flag with the syslog-parser() parser

The following example illustrates using the no-header flag with the syslog-parser() parser:
```
    parser p_syslog {
      syslog-parser(
        flags(no-header)
      );
    };
```
no-hostname: Enable the no-hostname flag if the log message does not include the hostname of the sender host. That way AxoSyslog assumes that the first part of the message header is ${PROGRAM} instead of ${HOST}. For example:
```
    source s_dell {
        network(
            port(2000)
            flags(no-hostname)
        );
    };
```
no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line. Note that this happens only if the underlying transport method actually supports multi-line messages. Currently the file() and pipe() drivers support multi-line messages.
no-parse: By default, AxoSyslog parses incoming messages as syslog messages. The no-parse flag completely disables syslog message parsing and processes the complete line as the message part of a syslog message. The AxoSyslog application will generate a new syslog header (timestamp, host, and so on) automatically and put the entire incoming message into the MESSAGE part of the syslog message (available using the ${MESSAGE} macro). This flag is useful for parsing messages not complying to the syslog format.

If you are using the flags(no-parse) option, then syslog message parsing is completely disabled, and the entire incoming message is treated as the ${MESSAGE} part of a syslog message. In this case, AxoSyslog generates a new syslog header (timestamp, host, and so on) automatically. Note that even though flags(no-parse) disables message parsing, some flags can still be used, for example, the no-multi-line flag.
sanitize-utf8: When using the sanitize-utf8 flag, AxoSyslog converts non-UTF-8 input to an escaped form, which is valid UTF-8.

Prior to version 4.6, this flag worked only when parsing RFC3164 messages. Starting with version 4.6, it works also for RFC5424 and raw messages.
store-legacy-msghdr: By default, AxoSyslog stores the original incoming header of the log message, so this flag is active. To disable it, use the dont-store-legacy-msghdr flag.
store-raw-message: Save the original message as received from the client in the ${RAWMSG} macro. You can forward this raw message in its original form to another AxoSyslog node using the syslog-ng() destination, or to a SIEM system, ensuring that the SIEM can process it. Available only in 3.16 and later.
syslog-protocol: The syslog-protocol flag specifies that incoming messages are expected to be formatted according to the new IETF syslog protocol standard (RFC5424), but without the frame header. Note that this flag is not needed for the syslog driver, which handles only messages that have a frame header.
validate-utf8: The validate-utf8 flag enables encoding-verification for messages.

Prior to version 4.6, this flag worked only when parsing RFC3164 messages. Starting with version 4.6, it works also for RFC5424 and raw messages.

For RFC5424-formatted messages, if the BOM character is missing, but the message is otherwise UTF-8 compliant, AxoSyslog automatically adds the BOM character to the message.

The byte order mark (BOM) is a Unicode character used to signal the byte-order of the message text.

follow-freq()


Type:	number
Default:	1

Description: Indicates that the source should be checked periodically. This is useful for files which always indicate readability, even though no new lines were appended. If this value is higher than zero, AxoSyslog will not attempt to use poll() on the file, but checks whether the file changed every time the follow-freq() interval (in seconds) has elapsed. Floating-point numbers (for example, 1.5) can be used 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 AxoSyslog 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 AxoSyslog to execute external applications.

Using `hook-commands()` when AxoSyslog starts or stops

To execute an external program when AxoSyslog starts or stops, use the following options:

`startup()`

Type:	string
Default:	N/A

Description: Defines the external program that is executed as AxoSyslog starts.

`shutdown()`

Type:	string
Default:	N/A

Description: Defines the external program that is executed as AxoSyslog stops.

Using the hook-commands() when AxoSyslog reloads

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

`setup()`

Type:	string
Default:	N/A

Description: Defines an external program that is executed when the AxoSyslog configuration is initiated, for example, on startup or during a AxoSyslog reload.

`teardown()`

Type:	string
Default:	N/A

Description: Defines an external program that is executed when the AxoSyslog configuration is stopped or torn down, for example, on shutdown or during a AxoSyslog reload.

Example: Using 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 AxoSyslog 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 AxoSyslog 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")
        )
     );
};

idle-timeout()


Accepted values:	number [seconds]
Default:	`0` (disabled)

Available in AxoSyslog 4.9 and later.

If set, AxoSyslog closes the client connection if no data is received for the specified amount of time (in seconds).

keep-timestamp()


Type:	yes or no
Default:	yes

Description: Specifies whether AxoSyslog should accept the timestamp received from the sending application or client. If disabled, the time of reception will be used instead. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

Warning To use the S_ macros, the keep-timestamp() option must be enabled (this is the default behavior of AxoSyslog).

log-fetch-limit()


Type:	number
Default:	100

Description: The maximum number of messages fetched from a source during a single poll loop. The destination queues might fill up before flow-control could stop reading if log-fetch-limit() is too high.

log-iw-size()


Type:	number
Default:	100

Description: The size of the initial window, this value is used during flow-control. Its value cannot be lower than 100, unless the dynamic-window-size() option is enabled. For details on flow-control, see Managing incoming and outgoing messages with flow-control.

log-msg-size()


Type:	number (bytes)
Default:	Use the global `log-msg-size()` option, which defaults to `65536` (64 KiB).

Description: Maximum length of an incoming message in bytes. This length includes the entire message (the data structure and individual fields). The maximal value that can be set is 268435456 bytes (256 MiB).

For messages using the IETF-syslog message format (RFC5424), the maximal size of the value of an SDATA field is 64 KiB.

Note In most cases, log-msg-size() does not need to be set higher than 10 MiB.

For details on how encoding affects the size of the message, see Message size and encoding.

You can use human-readable units when setting configuration options. For details, seeNotes about the configuration syntax.

Uses the value of the global option if not specified.

log-prefix() (DEPRECATED)


Type:	string
Default:

Description: A string added to the beginning of every log message. It can be used to add an arbitrary string to any log source, though it is most commonly used for adding kernel: to the kernel messages on Linux.

Note This option is deprecated. Use program-override instead.

multi-line-garbage()


Type:	regular expression
Default:	empty string

Description: Use the multi-line-garbage() option when processing multi-line messages that contain unneeded parts between the messages. Specify a string or regular expression that matches the beginning of the unneeded message parts. If the multi-line-garbage() option is set, AxoSyslog ignores the lines between the line matching the multi-line-garbage() and the next line matching multi-line-prefix(). See also the multi-line-prefix() option.

When receiving multi-line messages from a source when the multi-line-garbage() option is set, but no matching line is received between two lines that match multi-line-prefix(), AxoSyslog will continue to process the incoming lines as a single message until a line matching multi-line-garbage() is received.

To use the multi-line-garbage() option, set the multi-line-mode() option to prefix-garbage.

Warning If the multi-line-garbage() option is set, AxoSyslog discards lines between the line matching the multi-line-garbage() and the next line matching multi-line-prefix().

multi-line-mode()


Type:	`indented`, `prefix-garbage`, `prefix-suffix`, `regexp`, `smart`
Default:	empty string

Description: Use the multi-line-mode() option when processing multi-line messages. The AxoSyslog application provides the following methods to process multi-line messages:

indented: The indented mode can process messages where each line that belongs to the previous line is indented by whitespace, and the message continues until the first non-indented line. For example, the Linux kernel (starting with version 3.5) uses this format for /dev/log, as well as several applications, like Apache Tomcat.
```
    source s_tomcat {
        file("/var/log/tomcat/xxx.log" multi-line-mode(indented));
    };
```
prefix-garbage: The prefix-garbage mode uses a string or regular expression (set in multi-line-prefix()) that matches the beginning of the log messages, ignores newline characters from the source until a line matches the regular expression again, and treats the lines between the matching lines as a single message. For details on using multi-line-mode(prefix-garbage), see the multi-line-prefix() and multi-line-garbage() options.
prefix-suffix: The prefix-suffix mode uses a string or regular expression (set in multi-line-prefix()) that matches the beginning of the log messages, ignores newline characters from the source until a line matches the regular expression set in multi-line-suffix(), and treats the lines between multi-line-prefix() and multi-line-suffix() as a single message. Any other lines between the end of the message and the beginning of a new message (that is, a line that matches the multi-line-prefix() expression) are discarded. For details on using multi-line-mode(prefix-suffix), see the multi-line-prefix() and multi-line-suffix() options.

The prefix-suffix mode is similar to the prefix-garbage mode, but it appends the garbage part to the message instead of discarding it.
smart: The smart mode recognizes multi-line data backtraces even if they span multiple lines in the input. The backtraces are converted to a single log message for easier analysis. Backtraces for the following programming languages are recognized : Python, Java, JavaScript, PHP, Go, Ruby, and Dart.

smart mode is available in AxoSyslog version 4.2 and newer.

The regular expressions to recognize these programming languages are specified in an external file called /usr/share/syslog-ng/smart-multi-line.fsm (installation path depends on configure arguments), in a format that is described in that file.

Note

To format multi-line messages to your individual needs, consider the following:

To make multi-line messages more readable when written to a file, use a template in the destination and instead of the ${MESSAGE} macro, use the following: $(indent-multi-line ${MESSAGE}). This expression inserts a tab after every newline character (except when a tab is already present), indenting every line of the message after the first. For example:
```
    destination d_file {
        file ("/var/log/messages"
            template("${ISODATE} ${HOST} $(indent-multi-line ${MESSAGE})\n")
        );
    };
```
For details on using templates, see Templates and macros.
To actually convert the lines of multi-line messages to single line (by replacing the newline characters with whitespaces), use the flags(no-multi-line) option in the source.

multi-line-prefix()


Type:	regular expression starting with the ^ character
Default:	empty string

Description: Use the multi-line-prefix() option to process multi-line messages, that is, log messages that contain newline characters (for example, Tomcat logs). Specify a string or regular expression that matches the beginning of the log messages (always start with the ^ character). Use as simple regular expressions as possible, because complex regular expressions can severely reduce the rate of processing multi-line messages. If the multi-line-prefix() option is set, AxoSyslog ignores newline characters from the source until a line matches the regular expression again, and treats the lines between the matching lines as a single message. See also the multi-line-garbage() option.

Note

To format multi-line messages to your individual needs, consider the following:

To make multi-line messages more readable when written to a file, use a template in the destination and instead of the ${MESSAGE} macro, use the following: $(indent-multi-line ${MESSAGE}). This expression inserts a tab after every newline character (except when a tab is already present), indenting every line of the message after the first. For example:
```
    destination d_file {
        file ("/var/log/messages"
            template("${ISODATE} ${HOST} $(indent-multi-line ${MESSAGE})\n")
        );
    };
```
For details on using templates, see Templates and macros.
To actually convert the lines of multi-line messages to single line (by replacing the newline characters with whitespaces), use the flags(no-multi-line) option in the source.

Example: Processing Tomcat logs

The log messages of the Apache Tomcat server are a typical example for multi-line log messages. The messages start with the date and time of the query in the YYYY.MM.DD HH:MM:SS format, as you can see in the following example.

   2010.06.09. 12:07:39 org.apache.catalina.startup.Catalina start
    SEVERE: Catalina.start:
    LifecycleException:  service.getName(): "Catalina";  Protocol handler start failed: java.net.BindException: Address already in use null:8080
           at org.apache.catalina.connector.Connector.start(Connector.java:1138)
           at org.apache.catalina.core.StandardService.start(StandardService.java:531)
           at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
           at org.apache.catalina.startup.Catalina.start(Catalina.java:583)
           at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
           at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
           at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
           at java.lang.reflect.Method.invoke(Method.java:597)
           at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
           at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
           at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
           at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
           at java.lang.reflect.Method.invoke(Method.java:597)
           at org.apache.commons.daemon.support.DaemonLoader.start(DaemonLoader.java:177)
    2010.06.09. 12:07:39 org.apache.catalina.startup.Catalina start
    INFO: Server startup in 1206 ms
    2010.06.09. 12:45:08 org.apache.coyote.http11.Http11Protocol pause
    INFO: Pausing Coyote HTTP/1.1 on http-8080
    2010.06.09. 12:45:09 org.apache.catalina.core.StandardService stop
    INFO: Stopping service Catalina

To process these messages, specify a regular expression matching the timestamp of the messages in the multi-line-prefix() option. Such an expression is the following:

source s_file{file("/var/log/tomcat6/catalina.2010-06-09.log" follow-freq(0) multi-line-mode(regexp) multi-line-prefix("[0-9]{4}\.[0-9]{2}\.[0-9]{2}\.") flags(no-parse));};
    };

Note that flags(no-parse) is needed to prevent AxoSyslog trying to interpret the date in the message.

multi-line-suffix()


Type:	regular expression
Default:	empty string

Description: Use the multi-line-suffix() option when processing multi-line messages. Specify a string or regular expression that matches the end of the multi-line message.

To use the multi-line-suffix() option, set the multi-line-mode() option to prefix-suffix. See also the multi-line-prefix() option.

optional()


Type:	yes or no
Default:

Description: Instruct AxoSyslog to ignore the error if a specific source cannot be initialized. No other attempts to initialize the source will be made until the configuration is reloaded. This option currently applies to the pipe(), unix-dgram, and unix-stream drivers.

pad-size()


Type:	number
Default:	0

Description: Specifies input padding. Some operating systems (such as HP-UX) pad all messages to block boundary. This option can be used to specify the block size. The AxoSyslog application will pad reads from the associated device to the number of bytes set in pad-size(). Mostly used on HP-UX where /dev/log is a named pipe and every write is padded to 2048 bytes. If pad-size() was given and the incoming message does not fit into pad-size(), AxoSyslog will not read anymore from this pipe and displays the following error message:

   Padding was set, and couldn't read enough bytes

program-override()


Type:	string
Default:

Description: Replaces the ${PROGRAM} part of the message with the parameter string. For example, to mark every message coming from the kernel, include the program-override("kernel") option in the source containing /proc/kmsg.

tags()


Type:	string
Default:

Description: Label the messages received from the source with custom tags. Tags must be unique, and enclosed between double quotes. When adding multiple tags, separate them with comma, for example, tags("dmz", "router"). This option is available only in version 3.1 and later.

time-zone()


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

Description: The default timezone for messages read from the source. Applies only if no timezone is specified within the message itself.

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.

Last modified December 18, 2024: Merge pull request #90 from axoflow/minor-fixes-241218 (68cd7df)