# 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 | `obsolete legacy` directive
--- | --- | --- | ---
word | none | no | none

Name or address of the Redis server

#### ServerPort

type | default | mandatory | `obsolete legacy` directive
--- | --- | --- | ---
integer | 6379 | no | none

Port of the Redis server if the server is not listening on the default port.

#### ServerPassword

type | default | mandatory | `obsolete legacy` directive
--- | --- | --- | ---
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 | `obsolete legacy` directive
--- | --- | --- | ---
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 | `obsolete legacy` directive
--- | --- | --- | ---
word | RSYSLOG_ForwardFormat | no | none

Template is required if using “template” mode.

#### Key

type | default | mandatory | `obsolete legacy` directive
--- | --- | --- | ---
word | none | no | none

Key is required if using “publish”, “queue” or “set” modes.

#### Dynakey

type | default | mandatory | `obsolete legacy` directive
--- | --- | --- | ---
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 | `obsolete legacy` directive
--- | --- | --- | ---
binary | off | no | none

If set to on, use RPUSH instead of LPUSH, if not set or off, use LPUSH.

#### Expiration

type | default | mandatory | `obsolete legacy` directive
--- | --- | --- | ---
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 `Rsyslog`

- Stack 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.