Troubleshoot mgr in ceph Luminous

Note: change ceph1 according your server hostname

Check auth in ceph 

# ceph auth get mgr.ceph1
exported keyring for mgr.ceph1

[mgr.ceph1]
        key = AQDQn4pZkWQjKRAAmEQ45FZgqDeCL5i6ZhfS0g==
        caps mds = "allow *"
        caps mon = "allow profile mgr"
        caps osd = "allow *"

Create auth if needed by command
ceph auth get-or-create mgr.ceph1 mds 'allow *' mon 'allow profile mgr' osd 'allow *'

Check keying file and content in path /var/lib/ceph/mgr/ceph-ceph1

[root@ceph1 ceph-ceph1]# ls -l

total 4
-rw------- 1 ceph ceph 67 Aug  9 12:38 keyring

[root@ceph1 ceph-ceph1]# cat keyring

[mgr.ceph1]

        key = AQDQn4pZkWQjKRAAmEQ45FZgqDeCL5i6ZhfS0g==

Check mgr in systemd

# systemctl | grep mgr

systemctl reset-failed ceph-mgr@ceph1.service
systemctl enable ceph-mgr@ceph1.service
systemctl start ceph-mgr@ceph1.service