RabbitMQ cluster

Posted 2022-12-04 翟海飞

RabbitMQ概念及环境搭建（三）RabbitMQ cluster

测试环境：VMS00781 VMS00782 VMS00386 (CentOS5.8)
1.先在三台机器上分别安装RabbitMQ Server

2.读取其中一个节点的cookie，并复制到其他节点（节点间通过cookie确定相互是否可通信）
两者之一均可：
sudo vim /var/lib/rabbitmq/.erlang.cookie
sudo vim $HOME/.erlang.cookie

3.逐个启动节点
sudo service rabbitmq-server start

4.查看各节点中的RabbitMQ brokers
sudo rabbitmqctl cluster_status

5.建集群
分别在VMS00386、VMS00782 上执行
sudo rabbitmqctl stop_app
sudo rabbitmqctl join_cluster --ram rabbit@VMS00781
sudo rabbitmqctl start_app
sudo rabbitmqctl stop_app
sudo rabbitmqctl join_cluster rabbit@VMS00781
sudo rabbitmqctl start_app

6.排错
建集群过程中碰到如下错误：
sudo rabbitmqctl join_cluster --ram rabbit@VMS00386
Clustering node rabbit@VMS00782 with rabbit@VMS00386 ...
Error: unable to connect to nodes [rabbit@VMS00386]: nodedown
DIAGNOSTICS
===========
attempted to contact: [rabbit@VMS00386]
rabbit@VMS00386:
  * unable to connect to epmd (port 4369) on VMS00386: nxdomain (non-existing domain)
current node details:
- node name: 'rabbitmqctl-8666@VMS00782'
- home dir: /var/lib/rabbitmq
- cookie hash: 50YO3zK+HJHos0tab1vHjg==
解决之道：
集群节点间需能互相访问，故每个集群节点的hosts文件应包含集群内所有节点的信息以保证互相解析
vim /etc/hosts
781's IP  VMS00781
782's IP  VMS00782
386's IP  vms00386
之后重启各节点中的rabbitmq

7.其他问题
Error: mnesia_unexpectedly_running
原因：忘记先停止stop_app
解决：sudo rabbitmqctl stop_app

若rabbitmq-server第一次启动后hostname不能被解析或者发生了更改则会导致启动失败
需执行如下操作
sudo rm -rf /var/lib/rabbitmq/mnesia（因为相关信息会记录在此数据库）
重装RabbitMQ Server

#####################################################
RabbitMQ cluster 管理
#####################################################
1.查看集群状态
可分别在集群中各个节点执行
sudo rabbitmqctl cluster_status

2.更改节点类型（内存型或磁盘型）
sudo rabbitmqctl stop_app
sudo rabbitmqctl change_cluster_node_type disc
或
sudo rabbitmqctl change_cluster_node_type ram
sudo rabbitmqctl start_app

3.重启cluster中的节点
停止某个节点或者节点down掉剩余节点不受影响
[op1@vms00386 ~]$ sudo rabbitmqctl stop
Stopping and halting node rabbit@vms00386 ...

[op1@VMS00781 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00781 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782,rabbit@vms00386]],
 running_nodes,[rabbit@VMS00782,rabbit@VMS00781],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

[op1@VMS00782 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00782 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782,rabbit@vms00386]],
 running_nodes,[rabbit@VMS00781,rabbit@VMS00782],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

[op1@VMS00782 ~]$ sudo rabbitmqctl stop
Stopping and halting node rabbit@VMS00782 ...

[op1@VMS00781 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00781 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782,rabbit@vms00386]],
 running_nodes,[rabbit@VMS00781],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

待节点重启后自动追上其他节点
[op1@vms00386 ~]$ sudo service rabbitmq-server start
Starting rabbitmq-server: SUCCESS
rabbitmq-server.

[op1@VMS00781 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00781 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782,rabbit@vms00386]],
 running_nodes,[rabbit@vms00386,rabbit@VMS00781],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

[op1@VMS00782 ~]$ sudo service rabbitmq-server start
Starting rabbitmq-server: SUCCESS
rabbitmq-server.

[op1@VMS00781 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00781 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782,rabbit@vms00386]],
 running_nodes,[rabbit@VMS00782,rabbit@vms00386,rabbit@VMS00781],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

[op1@VMS00782 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00782 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782,rabbit@vms00386]],
 running_nodes,[rabbit@VMS00781,rabbit@vms00386,rabbit@VMS00782],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

[op1@vms00386 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@vms00386 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782,rabbit@vms00386]],
 running_nodes,[rabbit@VMS00782,rabbit@VMS00781,rabbit@vms00386],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

几点注意：
保证集群中至少有一个磁盘类型的节点以防数据丢失，在更改节点类型时尤其要注意。
若整个集群被停掉了，应保证最后一个down掉的节点被最先启动，若不能则要使用forget_cluster_node命令将其移出集群
若集群中节点几乎同时以不可控的方式down了此时在其中一个节点使用force_boot命令重启节点

4.从集群移除节点
[op1@vms00386 ~]$ sudo rabbitmqctl stop_app
Stopping node rabbit@vms00386 ...
[op1@vms00386 ~]$ sudo rabbitmqctl reset
Resetting node rabbit@vms00386 ...
[op1@vms00386 ~]$ sudo rabbitmqctl start_app
Starting node rabbit@vms00386 ...

[op1@vms00386 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@vms00386 ...
[nodes,[disc,[rabbit@vms00386]],
 running_nodes,[rabbit@vms00386],
 cluster_name,<<"rabbit@vms00386">>,
 partitions,[]]

[op1@VMS00781 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00781 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782]],
 running_nodes,[rabbit@VMS00782,rabbit@VMS00781],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

[op1@VMS00782 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00782 ...
[nodes,[disc,[rabbit@VMS00781,rabbit@VMS00782]],
 running_nodes,[rabbit@VMS00781,rabbit@VMS00782],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]
可见rabbit@vms00386成为了独立的节点，原集群只剩rabbit@VMS00781,rabbit@VMS00782了

也可在某个节点移除集群中其他节点
如继续在rabbit@VMS00781上移除rabbit@VMS00782
[op1@VMS00781 ~]$ sudo rabbitmqctl forget_cluster_node rabbit@VMS00782
Removing node rabbit@VMS00782 from cluster ...

[op1@VMS00781 ~]$ sudo rabbitmqctl cluster_status
Cluster status of node rabbit@VMS00781 ...
[nodes,[disc,[rabbit@VMS00781]],
 running_nodes,[rabbit@VMS00781],
 cluster_name,<<"rabbit@VMS00781">>,
 partitions,[]]

可见集群只剩rabbit@VMS00781一个节点了

这里有个问题，在远程其他节点中被移除的节点会自认为仍属于集群

[op1@VMS00782 ~]$ sudo rabbitmqctl start_app
Starting node rabbit@VMS00782 ...
BOOT FAILED
===========
Error description:
  error,inconsistent_cluster,"Node rabbit@VMS00782 thinks it's clustered with node rabbit@VMS00781, but rabbit@VMS00781 disagrees"
Log files (may contain more information):
  /var/log/rabbitmq/[e-mail]
  /var/log/rabbitmq/[e-mail]
Stack trace:
  [rabbit_mnesia,check_cluster_consistency,0,
    rabbit,'-start/0-fun-0-',0,
    rabbit,start_it,1,
    rpc,'-handle_call_call/6-fun-0-',5]
Error: rabbit,failure_during_boot,
          error,
              inconsistent_cluster,
                  "Node rabbit@VMS00782 thinks it's clustered with node rabbit@VMS00781, but rabbit@VMS00781 disagrees"
需要重置一下
[op1@VMS00782 ~]$ sudo rabbitmqctl reset
Resetting node rabbit@VMS00782 ...
[op1@VMS00782 ~]$ sudo rabbitmqctl start_app
Starting node rabbit@VMS00782 ...

此时三个节点均已成为独立的节点
其中rabbit@vms00386、rabbit@VMS00782均被重置为了新的RabbitMQ broker而rabbit@VMS00781还保留着原cluster的残留状态可通过如下步骤重置
[op1@VMS00781 ~]$ sudo rabbitmqctl stop_app
Stopping node rabbit@VMS00781 ...
[op1@VMS00781 ~]$ sudo rabbitmqctl reset
Resetting node rabbit@VMS00781 ...
[op1@VMS00781 ~]$ sudo rabbitmqctl start_app
Starting node rabbit@VMS00781 ...

5.自动配置cluster
显然，这是通过配置文件而非命令行工具进行的
首先重置各节点
[op1@VMS00781 ~]$ sudo rabbitmqctl stop_app
Stopping node rabbit@VMS00781 ...
[op1@VMS00781 ~]$ sudo rabbitmqctl reset
Resetting node rabbit@VMS00781 ...
...
其次调整配置文件
[rabbit,
  [cluster_nodes, ['rabbit@VMS00781', 'rabbit@VMS00782', 'rabbit@vms00386'], disc]].
...
之后启动各节点
[op1@VMS00781 ~]$ sudo service rabbitmq-server start
Starting rabbitmq-server: SUCCESS
rabbitmq-server.

查看集群状态
[op1@VMS00781 ~]$ sudo rabbitmqctl cluster_status

几点注意：
无论通过命令行还是通过配置文件配置，请确保各节点上Erlang和RabbitMQ版本一致
配置文件仅对新鲜节点有效，也即被reset或者第一次启动的节点。因此在重启节点后自动化集群过程并不会发生。也以为这通过rabbitmq进行的改变优先于自动化集群配置。

在一台机器上部署集群，一般用户测试集群特性
这里的关键是已不同的端口可节点名称启动多个rabbitmq-server实例，其余过程同多机器上部署集群类似

其他注意事项：
如防火墙策略等

参考：

http://www.rabbitmq.com/clustering.html

https://www.linuxidc.com/Linux/2014-12/110449p3.htm

openstack官方：https://docs.openstack.org/ha-guide/shared-messaging.html

问题参考：https://stackoverflow.com/questions/15720540/ubuntu-rabbitmq-error-unable-to-connect-to-node-rabbitsomename-nodedown