The date parser can extract dates from non-syslog messages. It operates by default on the ${MESSAGE} part of the log message, but can operate on any template or field provided. The parsed date will be available as the sender date (that is, the ${S_DATE}, ${S_ISODATE}, ${S_MONTH}, and so on, and related macros). (To store the parsed date as the received date, use the time-stamp(recvd) option.)
NOTE: Note that parsing will fail if the format string does not match the entire template or field. Since by default syslog-ng Open Source Edition (syslog-ng OSE) uses the ${MESSAGE} part of the log message, parsing will fail, unless the log message contains only a date, but that is unlikely, so practically you will have to segment the message (for example, using a csv-parser()) before using the date-parser(). You can also use date-parser() to parse dates received in a JSON or key-value-formatted log message.
Declaration
parser parser_name {
date-parser(
format("<format-string-for-the-date>")
template("<field-to-parse>'")
);
};
Example: Using the date-parser()
In the following example, syslog-ng OSE parses dates like 01/Jan/2016:13:05:05 PST from a field called MY_DATE using the following format string: format("%d/%b/%Y:%H:%M:%S %Z") (how you create this field from the incoming message is not shown in the example). In the destination template every message will begin with the timestamp in ISODATE format. Since the syslog parser is disabled, syslog-ng OSE will include the entire original message (including the original timestamp) in the ${MESSAGE} macro.
source s_file {
file("/tmp/input" flags(no-parse));
};
destination d_file {
file(
"/tmp/output"
template("${S_ISODATE} ${MESSAGE}\n")
);
};
log {
source(s_file);
parser { date-parser(format("%d/%b/%Y:%H:%M:%S %Z") template("${MY_DATE}")); };
destination(d_file);
};
In the template option, you can use template functions to specify which part of the message to parse with the format string. The following example selects the first 24 characters of the ${MESSAGE} macro.
date-parser(format("%d/%b/%Y:%H:%M:%S %Z") template("$(substr ${MESSAGE} 0 24)") );
In syslog-ng OSE version 3.23 and later, you can specify a comma-separated list of formats to parse multiple date formats with a single parser. For example:
date-parser(format(
"%FT%T.%f",
"%F %T,%f",
"%F %T"
));
If you need to modify or correct the timezone of the message after parsing, see Rewrite the timezone of a message.
The date-parser() parser has the following options.
format()
| Synopsis: |
format(string) |
| Default: |
|
Description: Specifies the format how syslog-ng OSE should parse the date. You can use the following format elements:
%% PERCENT
%a day of the week, abbreviated
%A day of the week
%b month abbr
%B month
%c MM/DD/YY HH:MM:SS
%C ctime format: Sat Nov 19 21:05:57 1994
%d numeric day of the month, with leading zeros (eg 01..31)
%e like %d, but a leading zero is replaced by a space (eg 1..31)
%f microseconds, leading 0's, extra digits are silently discarded
%D MM/DD/YY
%G GPS week number (weeks since January 6, 1980)
%h month, abbreviated
%H hour, 24 hour clock, leading 0's)
%I hour, 12 hour clock, leading 0's)
%j day of the year
%k hour
%l hour, 12 hour clock
%L month number, starting with 1
%m month number, starting with 01
%M minute, leading 0's
%n NEWLINE
%o ornate day of month -- "1st", "2nd", "25th", etc.
%p AM or PM
%P am or pm (Yes %p and %P are backwards :)
%q Quarter number, starting with 1
%r time format: 09:05:57 PM
%R time format: 21:05
%s seconds since the Epoch, UCT
%S seconds, leading 0's
%t TAB
%T time format: 21:05:57
%U week number, Sunday as first day of week
%w day of the week, numerically, Sunday == 0
%W week number, Monday as first day of week
%x date format: 11/19/94
%X time format: 21:05:57
%y year (2 digits)
%Y year (4 digits)
%Z timezone in ascii format (for example, PST), or in format -/+0000
%z timezone in ascii format (for example, PST), or in format -/+0000 (Required element)
|
|
CAUTION: When using the %z and %Z format elements, consider that while %z strictly expects a specified timezone, and triggers a warning if the timezone is not specified, %Z does not trigger a warning if the timezone is not specified.
For further information about the %z and %Z format elements, see the 'DESCRIPTION' section on the srtptime(3) - NetBSD Manual Pages. |
For example, for the date 01/Jan/2016:13:05:05 PST use the following format string: format("%d/%b/%Y:%H:%M:%S %Z")
In syslog-ng OSE version 3.23 and later, you can specify a comma-separated list of formats to parse multiple date formats with a single parser. For example:
date-parser(format(
"%FT%T.%f",
"%F %T,%f",
"%F %T"
));
template()
| Synopsis: |
template("${<macroname>}") |
Description: The macro that contains the part of the message that the parser will process. It can also be a macro created by a previous parser of the log path. By default, the parser processes the entire message (${MESSAGE}).
flags()
| Type: |
guess-timezone |
| Default: |
empty string |
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. For example:
date-parser(flags(guess-timezone));
time-stamp()
| Synopsis: |
stamp | recvd |
| Default: |
stamp |
Description: Determines if the parsed date values are treated as sent or received date. If you use time-stamp(stamp), syslog-ng OSE adds the parsed date to the S_ macros (corresponding to the sent date). If you use time-stamp(recvd), syslog-ng OSE adds the parsed date to the R_ macros (corresponding to the received date).
time-zone()
| Synopsis: |
time-zone(string) |
| Default: |
|
Description: If this option is set, syslog-ng OSE assumes that the parsed timestamp refers to the specified timezone. The timezone set in the time-zone() option overrides any timezone information parsed from the timestamp.
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.
The Python log parser (available in syslog-ng OSE version 3.10 and later) allows you to write your own parser in Python. Practically, that way you can process the log message (or parts of the log message) any way you need. For example, you can import external Python modules to process the messages, query databases to enrich the messages with additional data, and many other things.
The following points apply to using Python blocks in syslog-ng OSE in general:
-
Python parsers and template functions are available in syslog-ng OSE version 3.10 and later.
Python destinations and sources are available in syslog-ng OSE version 3.18 and later.
-
Supported Python versions: 2.7 and 3.4+ (if you are using pre-built binaries, check the dependencies of the package to find out which Python version it was compiled with).
-
The Python block must be a top-level block in the syslog-ng OSE configuration file.
-
If you store the Python code in a separate Python file and only include it in the syslog-ng OSE configuration file, make sure that the PYTHON_PATH environment variable includes the path to the Python file, and export the PYTHON_PATH environment variable. For example, if you start syslog-ng OSE manually from a terminal and you store your Python files in the /opt/syslog-ng/etc directory, use the following command: export PYTHONPATH=/opt/syslog-ng/etc
In production, when syslog-ng OSE starts on boot, you must configure your startup script to include the Python path. The exact method depends on your operating system. For recent Red Hat Enterprise Linux, Fedora, and CentOS distributions that use systemd, the systemctl command sources the /etc/sysconfig/syslog-ng file before starting syslog-ng OSE. (On openSUSE and SLES, /etc/sysconfig/syslog file.) Append the following line to the end of this file: PYTHONPATH="<path-to-your-python-file>", for example, PYTHONPATH="/opt/syslog-ng/etc"
-
The Python object is initiated every time when syslog-ng OSE is started or reloaded.
|
|
Caution:
If you reload syslog-ng OSE, existing Python objects are destroyed, therefore the context and state information of Python blocks is lost. Log rotation and updating the configuration of syslog-ng OSE typically involves a reload. |
-
The Python block can contain multiple Python functions.
-
Using Python code in syslog-ng OSE can significantly decrease the performance of syslog-ng OSE, especially if the Python code is slow. In general, the features of syslog-ng OSE are implemented in C, and are faster than implementations of the same or similar features in Python.
-
Validate and lint the Python code before using it. The syslog-ng OSE application does not do any of this.
-
Python error messages are available in the internal() source of syslog-ng OSE.
-
You can access the name-value pairs of syslog-ng OSE directly through a message object or a dictionary.
-
To help debugging and troubleshooting your Python code, you can send log messages to the internal() source of syslog-ng OSE. For details, see Logging from your Python code.
Declaration:
Python parsers consist of two parts. The first is a syslog-ng OSE parser object that you use in your syslog-ng OSE configuration, for example, in the log path. This parser references a Python class, which is the second part of the Python parsers. The Python class processes the log messages it receives, and can do virtually anything that you can code in Python.
parser <name_of_the_python_parser>{
python(
class("<name_of_the_python_class_executed_by_the_parser>")
);
};
python {
class MyParser(object):
def init(self, options):
'''Optional. This method is executed when syslog-ng is started or reloaded.'''
return True
def deinit(self):
'''Optional. This method is executed when syslog-ng is stopped or reloaded.'''
pass
def parse(self, msg):
'''Required. This method receives and processes the log message.'''
return True
};
Methods of the python() parser
The init (self, options) method (optional)
The syslog-ng OSE application initializes Python objects only when it is started or reloaded. That means it keeps the state of internal variables while syslog-ng OSE is running. The init method is executed as part of the initialization. You can perform any initialization steps that are necessary for your parser to work. For example, if you want to perform a lookup from a file or a database, you can open the file or connect to the database here, or you can initialize a counter that you will increase in the parse() method.
The return value of the init() method must be True. If it returns False, or raises an exception, syslog-ng OSE will not start.
options: This optional argument contains the contents of the options() parameter of the parser object as a Python dict.
parser my_python_parser{
python(
class("MyParser")
options("regex", "seq: (?P<seq>\\d+), thread: (?P<thread>\\d+), runid: (?P<runid>\\d+), stamp: (?P<stamp>[^ ]+) (?P<padding>.*$)")
);
};
class MyParser(object):
def init(self, options):
pattern = options["regex"]
self.regex = re.compile(pattern)
self.counter = 0
return True
The parse(self, log_message) method
The parse() method processes the log messages it receives, and can do virtually anything that you can code in Python. This method is required, otherwise syslog-ng OSE will not start.
The return value of the parse() method must be True. If it returns False, or raises an exception, syslog-ng OSE will drop the message.
-
To reference a name-value pair or a macro in the Python code, use the following format. For example, if the first argument in the definition of the function is called log-message, the value of the HOST macro is log-message['HOST'], and so on. (The log-message contains the entire log message (not just the text body) in a structure similar to a Python dict, but it is actually an object.)
-
You can define new name-value pairs in the Python function. For example, if the first argument in the definition of the function is called log-message, you can create a new name-value pair like this: log_message["new-macro-name"]="value". This is useful when you parse a part of the message from Python, or lookup a value based on data extracted from the log message.
Note that the names of the name-value pairs are case-sensitive. If you create a new name-value pair called new-macro-name in Python, and want to reference it in another part of the syslog-ng OSE configuration file (for example, in a template), use the ${new-macro-name} macro.
-
You cannot override hard macros (see Hard versus soft macros).
-
To list all available keys (names of name-value pairs), use the log_message.keys() function.
The deinit(self) method (optional)
This method is executed when syslog-ng OSE is stopped or reloaded.
|
|
Caution:
If you reload syslog-ng OSE, existing Python objects are destroyed, therefore the context and state information of Python blocks is lost. Log rotation and updating the configuration of syslog-ng OSE typically involves a reload. |
Example: Parse loggen logs
The following sample code parses the messages of the loggen tool (for details, see The loggen manual page). The following is a sample loggen message:
<38>2017-04-05T12:16:46 localhost prg00000[1234]: seq: 0000000000, thread: 0000, runid: 1491387406, stamp: 2017-04-05T12:16:46 PADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADD
The syslog-ng OSE parser object references the LoggenParser class and passes a set of regular expressions to parse the loggen messages. The init() method of the LoggenParser class compiles these expressions into a pattern. The parse method uses these patterns to extract the fields of the message into name-value pairs. The destination template of the syslog-ng OSE log statement uses the extracted fields to format the output message.
@version: 3.36
@include "scl.conf"
parser my_python_parser{
python(
class("LoggenParser")
options("regex", "seq: (?P<seq>\\d+), thread: (?P<thread>\\d+), runid: (?P<runid>\\d+), stamp: (?P<stamp>[^ ]+) (?P<padding>.*$)")
);
};
log {
source { tcp(port(5555)); };
parser(my_python_parser);
destination {
file("/tmp/regexparser.log.txt" template("seq: $seq thread: $thread runid: $runid stamp: $stamp my_counter: $MY_COUNTER"));
};
};
python {
import re
class LoggenParser(object):
def init(self, options):
pattern = options["regex"]
self.regex = re.compile(pattern)
self.counter = 0
return True
def deinit(self):
pass
def parse(self, log_message):
match = self.regex.match(log_message['MESSAGE'])
if match:
for key, value in match.groupdict().items():
log_message[key] = value
log_message['MY_COUNTER'] = self.counter
self.counter += 1
return True
return False
};
Example: Parse Windows eventlogs in Python - performance
The following example uses regular expressions to process Windows log messages received in XML format from the syslog-ng Agent for Windows application. The parser extracts different fields from messages received from the Security and the Application eventlog containers. Using the following configuration file, syslog-ng OSE could process about 25000 real-life Windows log messages per second.
@version: 3.36
options {
keep-hostname(yes);
keep-timestamp(no);
stats-level(2);
use-dns(no);
};
source s_network_aa5fdf25c39d4017a8e504cdb641b477 {
network(
flags(no-parse)
ip(0.0.0.0)
log-fetch-limit(1000)
log-iw-size(100000)
max-connections(100)
port(514)
);
};
parser p_python_parser_79c31da44bb64de6b5de84be4ae15a15 {
python(options("regex_for_security", ".* Security ID: (?P<security_id>\\S+) Account Name: (?P<account_name>\\S+) Account Domain: (?P<account_domain>\\S+) Logon ID: (?P<logon_id>\\S+).*Process Name: (?P<process_name>\\S+).*EventID (?P<event_id>\\d+)", "regex_others", "(.*)EventID (?P<event_id>\\d+)")
class("EventlogParser"));
};
destination d_file_78363e1dd90c4ebcbb0ee1eff5a2e310 {
file(
"/var/testdb_working_dir/fcd713a2-d48e-4025-9192-ec4a9852cafa.$HOST"
flush-lines(1000)
log-fifo-size(200000)
);
};
log {
source(s_network_aa5fdf25c39d4017a8e504cdb641b477);
parser(p_python_parser_79c31da44bb64de6b5de84be4ae15a15);
destination(d_file_78363e1dd90c4ebcbb0ee1eff5a2e310);
flags(flow-control);
};
python {
import re
class EventlogParser(object):
def init(self, options):
self.regex_security = re.compile(options["regex_for_security"])
self.regex_others = re.compile(options["regex_others"])
return True
def deinit(self):
pass
def parse(self, log_message):
security_match = self.regex_security.match(log_message['MESSAGE'])
if security_match:
for key, value in security_match.groupdict().items():
log_message[key] = value
else:
others_match = self.regex_others.match(log_message['MESSAGE'])
if others_match:
for key, value in others_match.groupdict().items():
log_message[key] = value
return True
};
The syslog-ng Open Source Edition (syslog-ng OSE) application can tag log messages, and can include these tags in the log messages, as described in Tagging messages. The tags-parser() can parse these tags from the incoming messages and re-tag them. That way if you add tags to a log message on a syslog-ng OSE client, the message will have the same tags on the syslog-ng OSE server. Available in version 3.23 and later.
Specify the macro that contains the list of tags to parse in the template() option of the parser, for example, the SDATA field that you used to transfer the tags, or the name of the JSON field that contains the tags after using the json-parser().
tags-parser(template("${<macro-or-field-with-tags>}"));
