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.
Declaration:
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>")
);
Example: Using the redis() driver
The following destination counts the number of log messages received per host.
destination d_redis {
redis(
host("localhost")
port(6379)
command("HINCRBY", "hosts", "$HOST", "1")
);
};
The following example creates a statistic from Apache webserver logs about the browsers that the visitors use (per minute)
@version: 3.36
source s_apache {
file("/var/log/apache2/access.log");
};
parser p_apache {
csv-parser(columns("APACHE.CLIENT_IP", "APACHE.IDENT_NAME", "APACHE.USER_NAME",
"APACHE.TIMESTAMP", "APACHE.REQUEST_URL", "APACHE.REQUEST_STATUS",
"APACHE.CONTENT_LENGTH", "APACHE.REFERER", "APACHE.USER_AGENT",
"APACHE.PROCESS_TIME", "APACHE.SERVER_NAME")
flags(escape-double-char,strip-whitespace)
delimiters(" ")
quote-pairs('""[]')
);
};
destination d_redis {
redis( command("HINCRBY" "${MONTH_ABBREV} ${DAY} ${HOUR}:${MIN}" "${APACHE.USER_AGENT}" "1"));
};
log {
source(s_apache);
parser(p_apache);
destination(d_redis);
};
Starting with version 3.34, you can send multiple log messages with the help of Redis's pipelining feature.
Batch size
The batch-lines(), batch-lines(), and batch-timeout() options of the destination determine how many log messages syslog-ng OSE sends in a batch. The batch-lines() option determines the maximum number of messages syslog-ng OSE puts in a batch in. This can be limited based on size and time:
syslog-ng OSE sends a batch every batch-timeout() milliseconds, even if the number of messages in the batch is less than batch-lines(). That way the destination receives every message in a timely manner even if suddenly there are no more messages.
To increase the performance of the destination, increase the number of worker threads for the destination using the workers() option, or adjust the batch-lines() and/or batch-timeout() options.
Example: Redis batch mode
The following destination sends log messages to a Redis server using the pipelining feature. A batch consists of 100 messages and is sent every 10 seconds (10000 milliseconds) if there is less than 100 messages are in the queue.
destination d_redis {
redis(
host("localhost")
port(6379)
command("HINCRBY", "hosts", "$HOST", "1")
batch-lines(100)
batch-timeout(10000)
log-fifo-size(100000)
);
};
The redis() driver sends messages as name-value pairs to a Redis key-value store.
The redis() destination has the following options:
auth()
| 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 3.10 and later.
batch-lines()
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.
batch-timeout()
| 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.
command()
| 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.
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: |
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.
|
|
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. | |
| compaction() |
| Type: |
yes|no |
| Default: |
no |
|
Description: If set to yes, syslog-ng OSE prunes the unused space in the LogMessage representation, making the disk queue size smaller at the cost of some CPU time. Setting the compaction() argument to yes is recommended when numerous name-value pairs are unset during processing, or when the same names are set multiple times. |
NOTE: Simply unsetting these name-value pairs by using the unset() rewrite operation is not enough, as due to performance reasons that help when syslog-ng is CPU bound, the internal representation of a LogMessage will not release the memory associated with these name-value pairs. In some cases, however, the size of this overhead becomes significant (the raw message size can grow up to four times its original size), which unnecessarily increases the disk queue file size. For these cases, the compaction will drop "unset" values, making the LogMessage representation smaller at the cost of some CPU time required to perform compaction.
| 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. |
NOTE: If the dir() path provided by the user does not exist, syslog-ng OSE creates the path with the same permission as the running instance. |
| 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.
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")
)
);
};
|
truncate-size-ratio() |
| Type: |
number (between 0 and 1) |
| Default: |
0.1 (10%) |
|
Description: Limits the truncation of the disk-buffer file. Truncating the disk-buffer file can slow down the disk IO operations, but it saves disk space, so syslog-ng only truncates the file, if the possible disk gain is more than truncate-size-ratio() times disk-buf-size().
|
|
Caution:
One Identity does not recommend you to change truncate-size-ratio(). Only change its value if you know the performance implications of doing so. | |
batch-bytes()
| 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 3.19 and later.
batch-lines()
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.
batch-timeout()
| 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.
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")
)
);
};
host()
| Type: |
hostname or IP address |
| Default: |
127.0.0.1 |
Description: The hostname or IP address of the Redis server.
port()
| Type: |
number |
| Default: |
6379 |
Description: The port number of the Redis server.
retries()
| Type: |
number (of attempts) |
| Default: |
3 |
Description: If syslog-ng OSE cannot send a message, it will try again until the number of attempts reaches retries().
If the number of attempts reaches retries(), syslog-ng OSE will wait for time-reopen() time, then tries sending the message again.
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-reopen()
| Accepted values: |
number [seconds] |
| Default: |
60 |
Description: The time to wait in seconds before a dead connection is reestablished.
workers()
Description: Specifies the number of worker threads (at least 1) that syslog-ng OSE uses to send messages to the server. Increasing the number of worker threads can drastically improve the performance of the destination.
|
|
Caution:
Hazard of data loss. When you use more than one worker threads together with disk-based buffering, syslog-ng OSE creates a separate disk buffer for each worker thread. This means that decreasing the number of workers can result in losing data currently stored in the disk buffer files. Do not decrease the number of workers when the disk buffer files are in use. |
If you are using load-balancing (that is, you have configured multiple servers in the url() option), increase the number of worker threads at least to the number of servers. For example, if you have set three URLs (url("site1", "site2", "site3")), set the workers() option to 3 or more.
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.
Declaration:
riemann(
server("<riemann-server-address>")
port("<riemann-server-port>")
metric("<the-metric-or-data-to-send-to-riemann>")
);
Example: Using the riemann() driver
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: 3.36
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.
