[RabbitMQ]Error: unable to connect to node rabbit@compute1: nodedown（CentOS7.0）

　　今天在搭建OpenStack的时候需要安装RabbitMQ，可是使用yum install rabbitmq-server安装之后，按照OpenStack官方提供的文档修改guest用户密码的时候却出现了如下错误：

[root@controller ~]# rabbitmqctl change_password guest Rabbit123
Changing password for user "guest" ...
Error: unable to connect to node rabbit@controller: nodedown

DIAGNOSTICS
===========

nodes in question: [rabbit@controller]

hosts, their running nodes and ports:
- controller: [{rabbitmqctl3435,40060}]

current node details:
- node name: rabbitmqctl3435@controller
- home dir: /var/lib/rabbitmq
- cookie hash: KkWnl06AR+v86hEhVTp8/g==

[root@controller ~]# 

　　殊不知，这并不是修改密码的命令除了问题，而是安装启动后就出现的问题。在启动服务后，在命令行输入：rabbitmqctl status，同样出现上述问题，如下：　　

[root@controller ~]# rabbitmqctl status
Status of node rabbit@controller ...
Error: unable to connect to node rabbit@controller: nodedown

DIAGNOSTICS
===========

nodes in question: [rabbit@controller]

hosts, their running nodes and ports:
- controller: [{rabbitmqctl3560,54352}]

current node details:
- node name: rabbitmqctl3560@controller
- home dir: /var/lib/rabbitmq
- cookie hash: KkWnl06AR+v86hEhVTp8/g==

[root@controller ~]# 

　　网上有人说是hostname的问题，结果测试了一下发现不行呀。

　　解决方案：执行如下两条命令：

　　　　# /sbin/service rabbitmq-server stop
　　　　# /sbin/service rabbitmq-server start
　　　　# rabbitmqctl status 测试正确，结果如下：

[root@compute1 home]# /sbin/service rabbitmq-server stop
Redirecting to /bin/systemctl stop  rabbitmq-server.service
[root@compute1 home]# /sbin/service rabbitmq-server start
Redirecting to /bin/systemctl start  rabbitmq-server.service
[root@compute1 home]# rabbitmqctl status
Status of node rabbit@compute1 ...
[{pid,22133},
 {running_applications,[{rabbit,"RabbitMQ","3.1.5"},
                        {os_mon,"CPO  CXC 138 46","2.2.14"},
                        {mnesia,"MNESIA  CXC 138 12","4.11"},
                        {xmerl,"XML parser","1.3.6"},
                        {sasl,"SASL  CXC 138 11","2.3.4"},
                        {stdlib,"ERTS  CXC 138 10","1.19.4"},
                        {kernel,"ERTS  CXC 138 10","2.16.4"}]},
 {os,{unix,linux}},
 {erlang_version,"Erlang R16B03-1 (erts-5.10.4) [source] [64-bit] [smp:6:6] [async-threads:30] [hipe] [kernel-poll:true]\n"},
 {memory,[{total,36056032},
          {connection_procs,2800},
          {queue_procs,5600},
          {plugins,0},
          {other_proc,13586448},
          {mnesia,59920},
          {mgmt_db,0},
          {msg_index,22280},
          {other_ets,739304},
          {binary,7880},
          {code,16441504},
          {atom,594537},
          {other_system,4595759}]},
 {vm_memory_high_watermark,0.4},
 {vm_memory_limit,6663997030},
 {disk_free_limit,1000000000},
 {disk_free,82596229120},
 {file_descriptors,[{total_limit,924},
                    {total_used,3},
                    {sockets_limit,829},
                    {sockets_used,1}]},
 {processes,[{limit,1048576},{used,127}]},
 {run_queue,0},
 {uptime,7}]
...done.
[root@compute1 home]#

 　　再次输入修改密码命令：rabbitmqctl change_password guest Rabbit123成功

[root@controller ~]# rabbitmqctl change_password guest Rabbit123
Changing password for user "guest" ...
...done.
[root@controller ~]#