环境信息：
系统：centos 7.5
Ceph：12.2.10
启动命令：
ceph mgr module disable dashboard
错误信息：
2018-12-04 15:41:55.125412 7fe6820b8700 1 mgr respawn respawning with exe /usr/bin/ceph-mgr
2018-12-04 15:41:55.125414 7fe6820b8700 1 mgr respawn exe_path /proc/self/exe
2018-12-04 15:41:55.163816 7f732a4d47c0 0 ceph version 12.2.10 (177915764b752804194937482a39e95e0ca3de94) luminous (stable), process ceph-mgr, pid 14757
2018-12-04 15:41:55.164030 7f732a4d47c0 0 pidfile_write: ignore empty --pid-file
2018-12-04 15:41:55.225414 7f732a4d47c0 1 mgr send_beacon standby
2018-12-04 15:41:55.243214 7f732183a700 1 mgr init Loading python module 'balancer'
2018-12-04 15:41:55.280542 7f732183a700 1 mgr init Loading python module 'dashboard'
2018-12-04 15:41:55.453851 7f732183a700 1 mgr init Loading python module 'restful'
2018-12-04 15:41:55.748108 7f732183a700 1 mgr init Loading python module 'status'
2018-12-04 15:41:56.196655 7f732183a700 1 mgr handle_mgr_map Activating!
2018-12-04 15:41:56.197021 7f732183a700 1 mgr handle_mgr_map I am now activating
2018-12-04 15:41:56.360952 7f730512a700 1 mgr load Constructed class from module: balancer
2018-12-04 15:41:56.362404 7f730512a700 1 mgr load Constructed class from module: dashboard
2018-12-04 15:41:56.363307 7f730512a700 1 mgr load Constructed class from module: restful
2018-12-04 15:41:56.363550 7f730512a700 1 mgr load Constructed class from module: status
2018-12-04 15:41:56.363621 7f730512a700 1 mgr send_beacon active
2018-12-04 15:41:56.365066 7f7302925700 1 mgr[restful] server not running: no certificate configured
2018-12-04 15:41:56.365420 7f730512a700 1 mgr[restful] Unknown request ''
2018-12-04 15:41:56.367565 7f730512a700 1 mgr[restful] Unknown request ''
2018-12-04 15:41:56.479631 7f7303126700 -1 log_channel(cluster) log [ERR] : Unhandled exception from module 'dashboard' while running on mgr.ceph-object-01: error('No socket could be created',)
2018-12-04 15:41:56.479642 7f7303126700 -1 dashboard.serve:
2018-12-04 15:41:56.479644 7f7303126700 -1 Traceback (most recent call last):
File "/usr/lib64/ceph/mgr/dashboard/module.py", line 1141, in serve
cherrypy.engine.start()
File "/usr/lib/python2.7/site-packages/cherrypy/process/wspbus.py", line 250, in start
raise e_info
ChannelFailures: error('No socket could be created',)
2018-12-04 15:41:57.226649 7f731e834700 1 mgr send_beacon active
2018-12-04 15:41:57.227381 7f731e834700 1 mgr.server send_report Not sending PG status to monitor yet, waiting for OSDs
问题分析：
因为我把centos7的ipv6关闭了所以报错了，mgr默认是同时开启ipv4和ipv6，解决方案是指定使用ipv4启动mgr。
解决方案：
ceph config-key set mgr/dashboard/server_addr 0.0.0.0
ceph mgr module disable dashboard
ceph mgr module enable dashboard
