decsis/rabbitmq-clusterer repository overview

⁠docker-rabbitmq-clusterer

This Docker image aims to provide a convinient way to launch rabbitmq clusters using the rabbitmq-clusterer⁠ plugin.

It provides two way to achieve this. One using environment variables to defines the cluster nodes and gospel node and other using Rancher metadata service⁠ to deploy in Rancher⁠ managed environments.

Clusterer version: rabbitmq_clusterer-3.6.x-667f92b0 Tested in Rancher 1.2.0

⁠ENV Variables based cluster

⁠CLUSTER_NODES

Fill accordingly clusterer configuration⁠. Only the nodes array content should be defined here:

CLUSTER_NODES="rabbit@hostA, {rabbit@hostD, disk}, {rabbit@hostB, ram}"

⁠CLUSTER_GOSPEL_NODE

Fill accordingly clusterer configuration⁠. Only the node name is necessary here:

CLUSTER_GOSPEL_NODE=rabbit@hostA

Launch a one node cluster:

docker run --rm -it --network=rabbitmqnet --hostname=NODE1 --name=NODE1 -e RABBITMQ_ERLANG_COOKIE='VERYSTRONGCOOKIE' -e CLUSTER_NODES=rabbit@NODE1 -e CLUSTER_GOSPEL_NODE=rabbit@NODE1 decsis/rabbitmq-clusterer

You must have noticed that I'm using a user-defined network. That is necessary for making use of the Embedded DNS server⁠ that Docker provides in such networks. Also both hostname and name are necessary. The name is for Docker serve the DNS entry with that name. The hostname is for each rabbit node recognize itself.

Finally the RABBITMQ_ERLANG_COOKIE must be set and be equal in all nodes all described in the RabbitMQ docs⁠.

Launch a second node:

docker run --rm -it --network=rabbitmqnet --hostname=NODE2 --name=NODE2 -e RABBITMQ_ERLANG_COOKIE='VERYSTRONGCOOKIE' -e CLUSTER_NODES="rabbit@NODE1,rabbit@NODE2" -e CLUSTER_GOSPEL_NODE=rabbit@NODE1 decsis/rabbitmq-clusterer

If the container appears to be hanged is default rabbitmq-clusterer behaviour to wait indefinitly for all the necessary conditions to create the configured cluster so it is indicative of something missing (can be a missing running node, a network access problem or something alike).

⁠Rancher Metadata based cluster

For this method is assumed that all nodes are part of the same Rancher service. Is necessary to set the variable:

RANCHER_MANAGED_CLUSTER=true

And you also have to instruct Rancher to use the container name as hostname.

Rancher docker-compose.yml example:

version: '2'
services:
  rabbit:
    image: decsis/rabbitmq-clusterer
    environment:
      RABBITMQ_ERLANG_COOKIE: ASTRONGERCOOKIE
      RANCHER_MANAGED_CLUSTER: 'true'        
    labels:          
      io.rancher.container.hostname_override: container_name
      

Then you just scale it up or down and the magic happens.