omhiredis: Redis Output Module¶
Module Name: | omhiredis |
Author: | Brian Knox <bknox@digitalocean.com> |
Purpose¶
This module provides native support for writing to Redis, using the hiredis client library.
Configuration Parameters¶
Note
Parameter names are case-insensitive.
Action Parameters¶
Server¶
type | default | mandatory |
|
|---|---|---|---|
word | none | no | none |
Name or address of the Redis server
ServerPort¶
type | default | mandatory |
|
|---|---|---|---|
integer | 6379 | no | none |
Port of the Redis server if the server is not listening on the default port.
ServerPassword¶
type | default | mandatory |
|
|---|---|---|---|
word | none | no | none |
Password to support authenticated redis database server to push messages across networks and datacenters. Parameter is optional if not provided AUTH command wont be sent to the server.
Mode¶
type | default | mandatory |
|
|---|---|---|---|
word | template | no | none |
Mode to run the output action in: “queue”, “publish” or “set”. If not supplied, the original “template” mode is used.
Note
Due to a config parsing bug in 8.13, explicitly setting this to “template” mode will result in a config parsing error.
If mode is “set”, omhiredis will send SET commands. If “expiration” parameter is provided (see parameter below), omhiredis will send SETEX commands.
Template¶
type | default | mandatory |
|
|---|---|---|---|
word | RSYSLOG_ForwardFormat | no | none |
Template is required if using “template” mode.
Key¶
type | default | mandatory |
|
|---|---|---|---|
word | none | no | none |
Key is required if using “publish”, “queue” or “set” modes.
Dynakey¶
type | default | mandatory |
|
|---|---|---|---|
binary | off | no | none |
If set to “on”, the key value will be considered a template by Rsyslog. Useful when dynamic key generation is desired.
Userpush¶
type | default | mandatory |
|
|---|---|---|---|
binary | off | no | none |
If set to on, use RPUSH instead of LPUSH, if not set or off, use LPUSH.
Expiration¶
type | default | mandatory |
|
|---|---|---|---|
number | 0 | no | none |
Only applicable with mode “set”. Specifies an expiration for the keys set by omhiredis. If this parameter is not specified, the value will be 0 so keys will last forever, otherwise they will last for X seconds.
Examples¶
Example 1: Template mode¶
In “template” mode, the string constructed by the template is sent to Redis as a command.
Note
This mode has problems with strings with spaces in them - full message won’t work correctly. In this mode, the template argument is required, and the key argument is meaningless.
module(load="omhiredis")
template(
name="program_count_tmpl"
type="string"
string="HINCRBY progcount %programname% 1")
action(
name="count_programs"
server="my-redis-server.example.com"
serverport="6379"
type="omhiredis"
mode="template"
template="program_count_tmpl")
Results¶
Here’s an example redis-cli session where we HGETALL the counts:
> redis-cli
127.0.0.1:6379> HGETALL progcount
1) "rsyslogd"
2) "35"
3) "rsyslogd-pstats"
4) "4302"
Example 2: Queue mode¶
In “queue” mode, the syslog message is pushed into a Redis list at “key”, using the LPUSH command. If a template is not supplied, the plugin will default to the RSYSLOG_ForwardFormat template.
module(load="omhiredis")
action(
name="push_redis"
server="my-redis-server.example.com"
serverport="6379"
type="omhiredis"
mode="queue"
key="my_queue")
Results¶
Here’s an example redis-cli session where we RPOP from the queue:
> redis-cli
127.0.0.1:6379> RPOP my_queue
"<46>2015-09-17T10:54:50.080252-04:00 myhost rsyslogd: [origin software=\"rsyslogd\" swVersion=\"8.13.0.master\" x-pid=\"6452\" x-info=\"http://www.rsyslog.com\"] start"
127.0.0.1:6379>
Example 3: Publish mode¶
In “publish” mode, the syslog message is published to a Redis topic set by “key”. If a template is not supplied, the plugin will default to the RSYSLOG_ForwardFormat template.
module(load="omhiredis")
action(
name="publish_redis"
server="my-redis-server.example.com"
serverport="6379"
type="omhiredis"
mode="publish"
key="my_channel")
Results¶
Here’s an example redis-cli session where we SUBSCRIBE to the topic:
> redis-cli
127.0.0.1:6379> subscribe my_channel
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "my_channel"
3) (integer) 1
1) "message"
2) "my_channel"
3) "<46>2015-09-17T10:55:44.486416-04:00 myhost rsyslogd-pstats: {\"name\":\"imuxsock\",\"origin\":\"imuxsock\",\"submitted\":0,\"ratelimit.discarded\":0,\"ratelimit.numratelimiters\":0}"
Example 4: Set mode¶
In “set” mode, the syslog message is set as a Redis key at “key”. If a template is not supplied, the plugin will default to the RSYSLOG_ForwardFormat template.
module(load="omhiredis")
action(
name="set_redis"
server="my-redis-server.example.com"
serverport="6379"
type="omhiredis"
mode="set"
key="my_key")
Results¶
Here’s an example redis-cli session where we get the key:
> redis-cli
127.0.0.1:6379> get my_key
"<46>2019-12-17T20:16:54.781239+00:00 localhost rsyslogd-pstats: { \"name\": \"main Q\", \"origin\": \"core.queue\",
\"size\": 3, \"enqueued\": 7, \"full\": 0, \"discarded.full\": 0, \"discarded.nf\": 0, \"maxqsize\": 3 }"
127.0.0.1:6379> ttl my_key
(integer) -1
Example 5: Set mode with expiration¶
In “set” mode when “expiration” is set to a positive integer, the syslog message is set as a Redis key at “key”, with expiration “expiration”. If a template is not supplied, the plugin will default to the RSYSLOG_ForwardFormat template.
module(load="omhiredis")
action(
name="set_redis"
server="my-redis-server.example.com"
serverport="6379"
type="omhiredis"
mode="set"
key="my_key"
expiration="10")
Results¶
Here’s an example redis-cli session where we get the key and test the expiration:
> redis-cli
127.0.0.1:6379> get my_key
"<46>2019-12-17T20:16:54.781239+00:00 localhost rsyslogd-pstats: { \"name\": \"main Q\", \"origin\": \"core.queue\",
\"size\": 3, \"enqueued\": 7, \"full\": 0, \"discarded.full\": 0, \"discarded.nf\": 0, \"maxqsize\": 3 }"
127.0.0.1:6379> ttl my_key
(integer) 10
127.0.0.1:6379> ttl my_key
(integer) 3
127.0.0.1:6379> ttl my_key
(integer) -2
127.0.0.1:6379> get my_key
(nil)
Example 6: Set mode with dynamic key¶
In any mode with “key” defined and “dynakey” as “on”, the key used during operation will be dynamically generated by Rsyslog using templating.
module(load="omhiredis")
template(name="example-template" type="string" string="%hostname%")
action(
name="set_redis"
server="my-redis-server.example.com"
serverport="6379"
type="omhiredis"
mode="set"
key="example-template"
dynakey="on")
Results¶
Here’s an example redis-cli session where we get the dynamic key:
> redis-cli
127.0.0.1:6379> keys *
(empty list or set)
127.0.0.1:6379> keys *
1) "localhost"
See also
Help with configuring/using Rsyslog:
Mailing list - best route for general questions
GitHub: rsyslog source project - detailed questions, reporting issues that are believed to be bugs with
RsyslogStack Exchange (View, Ask) - experimental support from rsyslog community
See also
Contributing to Rsyslog:
Source project: rsyslog project README.
Documentation: rsyslog-doc project README
Copyright 2008-2020 Rainer Gerhards (Großrinderfeld), and Others.