omamqp1: AMQP 1.0 Messaging Output Module

Purpose

This module provides the ability to send logging via an AMQP 1.0 compliant message bus. It puts the log messages into an AMQP message and sends the message to a destination on the bus.

Notable Features

• Message Format

• Interoperability

Configuration Parameters

Dependencies

• libqpid-proton

Configure

./configure --enable-omamqp1

Message Format

Messages sent from this module to the message bus contain an AMQP List in the message body. This list contains one or more log messages as AMQP String types. Each string entry is a single log message. The list is ordered such that the oldest log appears at the front of the list (e.g. list index 0), whilst the most recent log is at the end of the list.

Interoperability

The output plugin has been tested against the following messaging systems:

• QPID C++ Message Broker

• QPID Dispatch Message Router

TODO

• Add support for SSL connections.

Examples

module(load="omamqp1")
action(type="omamqp1"
       host="broker.amqp.org"
       target="amq.topic")

module(load="omamqp1")

action(type="omamqp1"
       host="bus.amqp.org"
       target="log-queue"
       username="joe"
       password="trustno1")

Notes on use with the QPID C++ broker (qpidd)

Note well: These notes assume use of version 0.34 of the QPID C++ broker. Previous versions may not be fully compatible.

To use the Apache QPID C++ broker qpidd as the message bus, a version of qpidd that supports the AMQP 1.0 protocol must be used.

Since qpidd can be packaged without AMQP 1.0 support you should verify AMQP 1.0 has been enabled by checking for AMQP 1.0 related options in the qpidd help text. For example:

qpidd --help

...

AMQP 1.0 Options:
   --domain DOMAIN           Domain of this broker
   --queue-patterns PATTERN  Pattern for on-demand queues
   --topic-patterns PATTERN  Pattern for on-demand topics

If no AMQP 1.0 related options appear in the help output then your instance of qpidd does not support AMQP 1.0 and cannot be used with this output module.

The destination for message (target) must be created before log messages arrive. This can be done using the qpid-config tool.

Example:

qpid-config add queue rsyslogd

Alternatively the target can be created on demand by configuring a queue-pattern (or topic-pattern) that matches the target. To do this, add a queue-patterns or topic_patterns configuration directive to the qpidd configuration file /etc/qpid/qpidd.conf.

For example to have qpidd automatically create a queue named rsyslogd add the following to the qpidd configuration file:

queue-patterns=rsyslogd

or, if a topic behavior is desired instead of a queue:

topic-patterns=rsyslogd

These dynamic targets are auto-delete and will be destroyed once there are no longer any subscribers or queue-bound messages.

Versions of qpidd <= 0.34 also need to have the SASL service name set to “amqp” if SASL authentication is used. Add this to the qpidd.conf file:

sasl-service-name=amqp

Notes on use with the QPID Dispatch Router (qdrouterd)

Note well: These notes assume use of version 0.5 of the QPID Dispatch Router qdrouterd. Previous versions may not be fully compatible.

The default qdrouterd configuration does not have SASL authentication turned on. If SASL authentication is required you must configure SASL in the qdrouter configuration file /etc/qpid-dispatch/qdrouterd.conf

First create a SASL configuration file for qdrouterd. This configuration file is usually /etc/sasl2/qdrouterd.conf, but its default location may vary depending on your platform’s configuration.

This document assumes you understand how to properly configure Cyrus SASL.

Here is an example qdrouterd SASL configuration file that allows the client to use either the DIGEST-MD5 or PLAIN authentication mechanisms and specifies the path to the SASL user credentials database:

pwcheck_method: auxprop
auxprop_plugin: sasldb
sasldb_path: /var/lib/qdrouterd/qdrouterd.sasldb
mech_list: DIGEST-MD5 PLAIN

Once a SASL configuration file has been set up for qdrouterd the path to the directory holding the configuration file and the name of the configuration file itself without the ‘.conf’ suffix must be added to the /etc/qpid-dispatch/qdrouterd.conf configuration file. This is done by adding saslConfigPath and saslConfigName to the container section of the configuration file. For example, assuming the file /etc/sasl2/qdrouterd.conf holds the qdrouterd SASL configuration:

container {
   workerThreads: 4
   containerName: Qpid.Dispatch.Router.A
   saslConfigPath: /etc/sasl2
   saslConfigName: qdrouterd
}

In addition the address used by the omamqp1 module to connect to qdrouterd must have SASL authentication turned on. This is done by adding the authenticatePeer attribute set to ‘yes’ to the corresponding listener entry:

listener {
   addr: 0.0.0.0
   port: amqp
   authenticatePeer: yes
}

This should complete the SASL setup needed by qdrouterd.

The target address used as the destination for the log messages must be picked with care. qdrouterd uses the prefix of the target address to determine the forwarding pattern used for messages sent to that target address. Addresses starting with the prefix queue are distributed to only one message receiver. If there are multiple message consumers listening to that target address only one listener will receive the message - mimicking the behavior of a queue with competing subscribers. For example: queue/rsyslogd

If a multicast pattern is desired - where all active listeners receive their own copy of the message - the target address prefix multicast may be used. For example: multicast/rsyslogd

Note well: if there are no active receivers for the log messages the messages will be rejected by qdrouterd since the messages are undeliverable. In this case the omamqp1 module will return a SUSPENDED status to the rsyslogd main task. rsyslogd may then re-submit the rejected log messages to the module which will attempt to send them again. This retry option is configured via rsyslogd - it is not part of this module. Refer to the rsyslogd actions documentation.

Using qdrouterd in combination with qpidd

A qdrouterd-based message bus can use a broker as a message storage mechanism for those that require broker-based message services (such as a message store). This section explains how to configure qdrouterd and qpidd for this type of deployment. Please read the above notes for deploying qpidd and qdrouterd first.

Each qdrouterd instance that is to connect the broker to the message bus must define a connector section in the qdrouterd.conf file. This connector contains the addressing information necessary to have the message bus set up a connection to the broker. For example, if a broker is available on host broker.host.com at port 5672:

connector {
   name: mybroker
   role: on-demand
   addr: broker.host.com
   port: 5672
}

In order to route messages to and from the broker, a static link route must be configured on qdrouterd. This link route contains a target address prefix and the name of the connector to use for forwarding matching messages.

For example, to have qdrouterd forward messages that have a target address prefixed by “Broker” to the connector defined above, the following link pattern must be added to the qdrouterd.conf configuration:

linkRoutePattern {
   prefix: /Broker/
   connector: mybroker
}

A queue must then be created on the broker. The name of the queue must be prefixed by the same prefix specified in the linkRoutePattern entry. For example:

$ qpid-config add queue Broker/rsyslogd

Lastly use the name of the queue for the target address for the omamqp module action. For example, assuming qdrouterd is listening on local port 5672:

action(type="omamqp1"
       host="localhost:5672"
       target="Broker/rsyslogd")

Copyright 2008-2023 Rainer Gerhards (Großrinderfeld), and Others.