The Python destination allows you to write your own destination in Python. The python() destination has the following options. The class() option is mandatory. For details on writing destinations in Python, see python: writing custom Python destinations.
Accepted values: | number [bytes] |
Default: | none |
Description: Sets the maximum size of payload in a batch. If the size of the messages reaches this value, syslog-ng OSE sends the batch to the destination even if the number of messages is less than the value of the batch-lines() option.
Note that if the batch-timeout() option is enabled and the queue becomes empty, syslog-ng OSE flushes the messages only if batch-timeout() expires, or the batch reaches the limit set in batch-bytes().
Available in syslog-ng OSE version
This option does not have any effect unless the flush() method is implemented in the destination.
Type: | number |
Default: | 25 |
Description: Specifies how many lines are flushed to a destination in one batch. 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.
For example, if you set batch-lines() to 100, syslog-ng OSE waits for 100 messages.
If the batch-timeout() option is disabled, the syslog-ng OSE application flushes the messages if it has sent batch-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.
Note that if the batch-timeout() option is enabled and the queue becomes empty, syslog-ng OSE flushes the messages only if batch-timeout() expires, or the batch reaches the limit set in batch-lines().
For optimal performance, make sure that the syslog-ng OSE source that feeds messages to this destination is configured properly: the value of the log-iw-size() option of the source must be higher than the batch-lines()*workers() of the destination. Otherwise, the size of the batches cannot reach the batch-lines() limit.
This option does not have any effect unless the flush() method is implemented in the destination.
Type: | time in milliseconds |
Default: | -1 (disabled) |
Description: Specifies the time syslog-ng OSE waits for lines to accumulate in the output buffer. The syslog-ng OSE application sends batches to the destinations evenly. The timer starts when the first message arrives to the buffer, so if only few messages arrive, syslog-ng OSE sends messages to the destination at most once every batch-timeout() milliseconds.
This option does not have any effect unless the flush() method is implemented in the destination.
Type: | string |
Default: | N/A |
Description: The name of the Python class that implements the destination, for example:
python( class("MyPythonDestination") );
If you want to store the Python code in an external Python file, the class() option must include the name of the Python file containing the class, without the path and the .py extension, for example:
python( class("MyPythonfilename.MyPythonDestination") );
For details, see Python code in external files
Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:
reliable() | |||
Type: | yes|no | ||
Default: | no | ||
Description: If set to yes, syslog-ng 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.
|
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. Note that if you change the value of this option and the disk-buffer already exists, the change will take effect when the disk-buffer becomes empty. |
Options reliable() and disk-buf-size() are required options.
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") ) ); };
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.
Type: | list of python modules |
Default: | empty list |
Description: The syslog-ng OSE application imports Python modules specified in this option, before importing the code of the Python class. This option has effect only when the Python class is provided in an external Python file. This option has no effect when the Python class is provided within the syslog-ng OSE configuration file (in a python{} block). You can use the loaders() option to modify the import mechanism that imports Python class. For example, that way you can use hy in your Python class.
python(class(usermodule.HyParser) loaders(hy))
Type: | number |
Default: | Use global setting. |
Description: The number of messages that the output queue can store.
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.
Type: | string |
Default: | N/A |
Description: This option allows you to pass custom values from the configuration file to the Python code. Enclose both the option names and their values in double-quotes. The Python code will receive these values during initialization as the options dictionary. For example, you can use this to set the IP address of the server from the configuration file, so it is not hard-coded in the Python object.
python( class("MyPythonClass") options( "host" "127.0.0.1" "port" "1883" "otheroption" "value") );
For example, you can refer to the value of the host field in the Python code as options["host"]. Note that the Python code receives the values as strings, so you might have to cast them to the type required, for example: int(options["port"])
Type: | string |
Default: |
Description:If you receive the following error message during syslog-ng OSE startup, set the persist-name() option of the duplicate drivers:
Error checking the uniqueness of the persist names, please override it with persist-name option. Shutting down.
This error happens if you use identical drivers in multiple sources, for example, if you configure two file sources to read from the same file. In this case, set the persist-name() of the drivers to a custom string, for example, persist-name("example-persist-name1").
Starting with
log { source { python(class(PyNetworkSource) options("port" "8080") persist-name("<unique-string>); }; source { python(class(PyNetworkSource) options("port" "8081")); }; };
Alternatively, you can include the following line in the Python package: @staticmethod generate_persist_name. For example:
from syslogng import LogSource class PyNetworSource(LogSource): @staticmethod def generate_persist_name(options): return options["port"] def run(self): pass def request_exit(self): pass
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.
Type: | parameter list of the value-pairs() option |
Default: | scope("selected-macros" "nv-pairs") |
Description: The value-pairs() option creates structured name-value pairs from the data and metadata of the log message. For details on using value-pairs(), see Structuring macros, metadata, and other value-pairs.
Empty keys are not logged.
You can use this option to limit which name-value pairs are passed to the Python code for each message. Note that if you use the value-pairs() option, the Python code receives the specified value-pairs as a Python dict. Otherwise, it receives the message object. In the following example, only the text of the log message is passed to Python.
destination d_python_to_file { python( class("pythonexample.TextDestination") value-pairs(key(MESSAGE)) ); };
The redis() driver sends messages as name-value pairs to a Redis key-value store.
For the list of available parameters, see redis() destination options.
redis( host("<redis-server-address>") port("<redis-server-port>") auth("<redis-server-password>") # Optional, for password-protected servers command("<redis-command>", "<first-command-parameter>", "<second-command-parameter>", "<third-command-parameter>") );
The following destination counts the number of log messages received per host.
destination d_redis { redis( host("localhost") port(6379) command("HINCRBY", "hosts", "$HOST", "1") ); };
The following example creates a statistic from Apache webserver logs about the browsers that the visitors use (per minute)
@version: 3.25 source s_apache { file("/var/log/apache2/access.log"); }; parser p_apache { csv-parser(columns("APACHE.CLIENT_IP", "APACHE.IDENT_NAME", "APACHE.USER_NAME", "APACHE.TIMESTAMP", "APACHE.REQUEST_URL", "APACHE.REQUEST_STATUS", "APACHE.CONTENT_LENGTH", "APACHE.REFERER", "APACHE.USER_AGENT", "APACHE.PROCESS_TIME", "APACHE.SERVER_NAME") flags(escape-double-char,strip-whitespace) delimiters(" ") quote-pairs('""[]') ); }; destination d_redis { redis( command("HINCRBY" "${MONTH_ABBREV} ${DAY} ${HOUR}:${MIN}" "${APACHE.USER_AGENT}" "1")); }; log { source(s_apache); parser(p_apache); destination(d_redis); };
The redis() driver sends messages as name-value pairs to a Redis key-value store.
The redis() destination has the following options:
Type: | hostname or IP address |
Default: | N/A |
Description: The password used for authentication on a password-protected Redis server. Available in syslog-ng OSE version
Type: | comma-separated list of strings ("<redis-command>", "<first-command-parameter>", "<second-command-parameter>", "<third-command-parameter>") |
Default: | empty string |
Description: The Redis command to execute, for example, LPUSH, INCR, or HINCRBY. Using the HINCRBY command with an increment value of 1 allows you to create various statistics. For example, the command("HINCRBY" "${HOST}/programs" "${PROGRAM}" "1") command counts the number of log messages on each host for each program.
Note the following points when using the redis() destination:
You can use macros and templates in the parameters of the Redis command.
Currently you can use only one command in a redis() destination.
The syslog-ng OSE application ignores the return value of the command. If the Redis server returns an error, syslog-ng OSE closes the connection.
Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:
reliable() | |||
Type: | yes|no | ||
Default: | no | ||
Description: If set to yes, syslog-ng 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.
|
dir() | |||
Type: | string | ||
Default: | N/A | ||
Description: Defines the folder where the disk-buffer files are stored.
|
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. Note that if you change the value of this option and the disk-buffer already exists, the change will take effect when the disk-buffer becomes empty. |
Options reliable() and disk-buf-size() are required options.
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") ) ); };
Accepted values: | number [bytes] |
Default: | none |
Description: Sets the maximum size of payload in a batch. If the size of the messages reaches this value, syslog-ng OSE sends the batch to the destination even if the number of messages is less than the value of the batch-lines() option.
Note that if the batch-timeout() option is enabled and the queue becomes empty, syslog-ng OSE flushes the messages only if batch-timeout() expires, or the batch reaches the limit set in batch-bytes().
Available in syslog-ng OSE version
Type: | number |
Default: | 1 |
Description: Specifies how many lines are flushed to a destination in one batch. 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.
For example, if you set batch-lines() to 100, syslog-ng OSE waits for 100 messages.
If the batch-timeout() option is disabled, the syslog-ng OSE application flushes the messages if it has sent batch-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.
Note that if the batch-timeout() option is enabled and the queue becomes empty, syslog-ng OSE flushes the messages only if batch-timeout() expires, or the batch reaches the limit set in batch-lines().
For optimal performance, make sure that the syslog-ng OSE source that feeds messages to this destination is configured properly: the value of the log-iw-size() option of the source must be higher than the batch-lines()*workers() of the destination. Otherwise, the size of the batches cannot reach the batch-lines() limit.
Type: | time in milliseconds |
Default: | -1 (disabled) |
Description: Specifies the time syslog-ng OSE waits for lines to accumulate in the output buffer. The syslog-ng OSE application sends batches to the destinations evenly. The timer starts when the first message arrives to the buffer, so if only few messages arrive, syslog-ng OSE sends messages to the destination at most once every batch-timeout() milliseconds.
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.
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. |
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. |
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") ) ); };
Type: | hostname or IP address |
Default: | 127.0.0.1 |
Description: The hostname or IP address of the Redis server.
Type: | number |
Default: | 6379 |
Description: The port number of the Redis server.
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.
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.
The riemann() driver sends your data (for example, metrics or events) to a Riemann monitoring system.
For the list of available parameters, see riemann() destination options.
riemann( server("<riemann-server-address>") port("<riemann-server-port>") metric("<the-metric-or-data-to-send-to-riemann>") );
The following destination sends the value of the SEQNUM macro (the number of messages sent to this destination) as a metric to the Riemann server.
@version: 3.25 source s_network { network(port(12345)); }; destination d_riemann { riemann( server("localhost") port(5555) ttl("300.5") metric(int("$SEQNUM")) description("syslog-ng riemann test") state("ok") attributes(x-ultimate-answer("$(+ $PID 42)") key("MESSAGE", rekey(add-prefix("x-")) ) ) ); }; log { source(s_network); destination(d_riemann); flags(flow-control); };
For a detailed use-case on using syslog-ng OSE with the Riemann monitoring system, see the article A How to Guide on Modern Monitoring and Alerting by Fabien Wernli.
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