# omrabbitmq: RabbitMQ output module

Module Name: | omrabbitmq
Authors: | Jean-Philippe Hilaire <jean-philippe.hilaire@pmu.fr> & Philippe Duveau <philippe.duveau@free.fr>

## Purpose

This module sends syslog messages into RabbitMQ server. Only v6 configuration syntax is supported.

omrabbitmq is tested and is running in production with 8.x version of rsyslog.

## Compile

To successfully compile omrabbitmq module you need rabbitmq-c library version >= 0.4.

> ./configure –enable-omrabbitmq …

## Configuration Parameters

### Action Parameters

#### host

type | mandatory | format | default
--- | --- | --- | ---
string | yes | hostname[:port][ hostname2[:port2]] |

rabbitmq server(s). See HA configuration

#### port

type | mandatory | format | default
--- | --- | --- | ---
string | no | port | 5672

#### virtual_host

type | mandatory | format | default
--- | --- | --- | ---
string | yes | path |

virtual message broker

#### user

type | mandatory | format | default
--- | --- | --- | ---
string | yes | user |

user name

#### password

type | mandatory | format | default
--- | --- | --- | ---
string | yes | password |

user password

#### exchange

type | mandatory | format | default
--- | --- | --- | ---
string | no | name |

exchange name

#### routing_key

type | mandatory | format | default
--- | --- | --- | ---
string | no | name |

value of routing key

#### routing_key_template

type | mandatory | format | default
--- | --- | --- | ---
string | no | template_name |

template used to compute the routing key

#### body_template

type | mandatory | format | default
--- | --- | --- | ---
string | no | template | StdJSONFmt

template used to compute the message body. If the template is an empty string the sent message will be %rawmsg%

#### delivery_mode

type | mandatory | format | default
--- | --- | --- | ---
string | no | TRANSIENT|PERSISTANT | TRANSIENT

persistence of the message in the broker

#### expiration

type | mandatory | format | default
--- | --- | --- | ---
string | no | milliseconds | no expiration

ttl of the amqp message

#### populate_properties

type | mandatory | format | default
--- | --- | --- | ---
binary | no |  | off

fill timestamp, appid, msgid, hostname (custom header) with message informations

#### content_type

type | mandatory | format | default
--- | --- | --- | ---
string | no | value |

content type as a MIME value

#### declare_exchange

type | mandatory | format | default
--- | --- | --- | ---
binary | no | off |

Rsyslog tries to declare the exchange on startup. Declaration failure (already exists with different parameters or insufficient rights) is warned but does not cancel the module instance.

#### recover_policy

type | mandatory | format | default
--- | --- | --- | ---
string | no | check_interval;short_failure_interval; short_failure_nb_max;graceful_interval | 60;6;3;600

See HA configuration

## HA configuration

The module can use two rabbitmq server in a fail-over mode. To configure this mode, the host parameter has to reference the two rabbitmq servers separated by space. Each server can be optionally completed with the port (useful when they are different). One of the servers is chosen on startup as a preferred one. The module connects to this server with a fail-over policy which can be defined through the action parameter “recover_policy”.

The module launch a back-ground thread to monitor the connection. As soon as the connection fails, the thread retries to restablish the connection and switch to the back-up server if needed to recover the service. While connected to backup server, the thread tries to reconnect to the preferred server using a “recover_policy”. This behaviour allow to load balance the client across the two rabbitmq servers on normal conditions, switch to the running server in case of failure and rebalanced on the two server as soon as the failed server is recovered without restarting clients.

The recover policy is based on 4 parameters :

- check_interval is the base duration between connection retries (default is 60 seconds)

- short_failure_interval is a duration under which two successive failures are considered as abnormal for the rabbitmq server (default is check_interval/10)

- short_failure_nb_max is the number of successive short failure are detected before to apply the graceful interval (default is 3)

- graceful_interval is a longer duration used if the rabbitmq server is unstable (default is check_interval*10).

The short failures detection is applied in case of unstable network or server and force to switch to back-up server for at least ‘graceful-interval’ avoiding heavy load on the unstable server. This can avoid dramatic scenarios in a multisites deployment.

## Examples

### Example 1

This is the simplest action :

- No High Availability

- The routing-key is constant

- The sent message use JSON format

    module(load='omrabbitmq')
    action(type="omrabbitmq"
           host="localhost"
           virtual_host="/"
           user="guest"
           password="guest"
           exchange="syslog"
           routing_key="syslog.all")

### Example 2

Action characteristics :

- No High Availability

- The routing-key is computed

- The sent message is a raw message

    module(load='omrabbitmq')
    template(name="rkTpl" type="string" string="%syslogtag%.%syslogfacility-text%.%syslogpriority-text%")

    action(type="omrabbitmq"
           host="localhost"
           virtual_host="/"
           user="guest"
           password="guest"
           exchange="syslog"
           routing_key_template="rkTpl"
           template_body="")

### Example 3

HA action :

- High Availability between server1:5672 and server2:1234

- The routing-key is computed

- The sent message is formatted using RSYSLOG_ForwardFormat standard template

    module(load='omrabbitmq')
    template(name="rkTpl" type="string" string="%syslogtag%.%syslogfacility-text%.%syslogpriority-text%")

    action(type="omrabbitmq"
           host="server1 server2:1234"
           virtual_host="production"
           user="guest"
           password="guest"
           exchange="syslog"
           routing_key_template="rkTpl"
           template_body="RSYSLOG_ForwardFormat")

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.