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I'm trying to setup a cluster of RabbitMQ servers, to get highly available queues using an active/passive server architecture. I'm following this guides:
My requirement for high availability is simple, i have two nodes (CentOS 6.4) with RabbitMQ (v3.2) and Erlang R15B03. The Node1 must be the "active", responding all requests, and the Node2 must be the "passive" node that has all the queues and messages replicated (from Node1).
To do that, i have configured the following:
The next I did was to create a cluster between both nodes: joining Node2 to Node1 (guide 1). After that I configured a policy to make mirroring of the queues (guide 2), replicating all the queues and messages among all the nodes in the cluster. This works, i can connect to any node and publish or consume message, while both nodes are available.
The problem occurs when i have a queue "queueA" that was created on the Node1 (master on queueA), and when Node1 is stopped, I can't connect to the queueA in the Node2 to produce or consume messages, Node2 throws an error saying that Node1 is not accessible (I think that queueA is not replicated to Node2, and Node2 can't be promoted as master of queueA).
The error is:
{"The AMQP operation was interrupted: AMQP close-reason, initiated by Peer, code=404, text=\"NOT_FOUND - home node 'rabbit@node1' of durable queue 'queueA' in vhost 'app01' is down or inaccessible\", classId=50, methodId=10, cause="}
The sequence of steps used is:
Node1:
1. rabbitmq-server -detached
2. rabbitmqctl start_app
Node2:
3. Copy .erlang.cookie from Node1 to Node2
4. rabbitmq-server -detached
Join the cluster (Node2):
5. rabbitmqctl stop_app
6. rabbitmqctl join_cluster rabbit@node1
7. rabbitmqctl start_app
Configure Queue mirroring policy:
8. rabbitmqctl set_policy ha-all "" '{"ha-mode":"all","ha-sync-mode":"automatic"}'
Note: The pattern used for queue names is "" (all queues).
When I run 'rabbitmqctl list_policies' and 'rabbitmqctl cluster_status' is everything ok.
Why the Node2 cannot respond if Node1 is unavailable? Is there something wrong in this setup?
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RabbitMQ High Availability can only be set up on the sets of nodes that come under the same cluster. RabbitMQ's High Availability is achieved by mirroring the queues across different RabbitMQ Nodes in a cluster. As a result, you need to set up a cluster as a prerequisite for setting up RabbitMQ's High Availability.
RabbitMQ offers features of High Availability (HA). High availability refers to automated failover from one instance to another in case of disk failure or a limited network outage. The impact of failure on availability should be very minimal or should not be seen.
RabbitMQ supports: clustering of multiple nodes. synchronous replication - replicated queues.
RabbitMQ is an open source message broker. It uses a publish-subscribe model to route data from publishers to consumers. It is scalable and can be load balanced, acting as a reliable and highly available intermediary. It has support for management and monitoring and has a range of tools and plugins available.
Only mirror queue which are synchronized with the master are promoted to be master, after fails. This is default behavior, but can be changed to promote-on-shutdown always.
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