Message queue

1. OpenStack 使用 message queue 訊息佇列來協調服務之間的操作和狀態訊息，OpenStack 支援多種訊息佇列服務，包括 RabbitMQ，Qpid 和 ZeroMQ，本文件使用 RabbitMQ安裝 rabbitmq-server。

   [root@ip112 ~]# yum install rabbitmq-server
   

2. 啟動 rabbitmq-server 服務，並設定開機啟動。

   [root@ip112 ~]# systemctl enable rabbitmq-server.service 
   Created symlink from /etc/systemd/system/multi-user.target.wants/rabbitmq-server.service 
   to /usr/lib/systemd/system/rabbitmq-server.service.
   
   [root@ip112 ~]# systemctl start rabbitmq-server.service 
   [root@ip112 ~]# systemctl status rabbitmq-server.service 
   ● rabbitmq-server.service - RabbitMQ broker
      Loaded: loaded (/usr/lib/systemd/system/rabbitmq-server.service; enabled; vendor preset: disabled)
      Active: active (running) since Wed 2018-05-23 16:54:02 CST; 9s ago
    Main PID: 12046 (beam.smp)
      Status: "Initialized"
      CGroup: /system.slice/rabbitmq-server.service
              ├─12046 /usr/lib64/erlang/erts-8.3.5.3/bin/beam.smp -W w -A 640 -...
              ├─12884 erl_child_setup 1024
              ├─12930 inet_gethost 4
              └─12931 inet_gethost 4
   
   May 23 16:54:02 ip112.csie.cyut.edu.tw systemd[1]: Started RabbitMQ broker.
   Hint: Some lines were ellipsized, use -l to show in full.
   

3. rabbitmq 新增 openstak 用戶，最後一個參數 RABBIT_PASS 為密碼，請更改成自己適用的密碼。

   [root@ip112 ~]# rabbitmqctl add_user openstack RABBIT_PASS
   Creating user "openstack" ...
   

4. rabbitmq 設定 openstak 用戶有讀取及寫入的權限。

   [root@ip112 ~]# rabbitmqctl set_permissions openstack ".*" ".*" ".*"
   Setting permissions for user "openstack" in vhost "/" ...
   

5. 列印權限。

   [root@ip112 ~]# rabbitmqctl list_permissions
   Listing permissions in vhost "/" ...
   openstack	.*	.*	.*
   guest	.*	.*	.*