I have Docker Swarm cluster setup with docker0 and docker_gwbrigde virtual network adapters set as it should be by default, containers are UP and everything works just fine. The problem is with triggering check_mk monitoring alarm by docker0 interface which link state appears to be in DOWN state on some Docker hosts.
Interesting part is that when I check docker0 interface status it shows IP, MAC, broadcast address, route, etc. I can also ping 172.17.0.1.
On other Docker hosts in cluster both interfaces are in UP state and I don’t have problem with them regarding to triggering check_mk alarm.
6: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 02:42:c3:d8:a1:48 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
valid_lft forever preferred_lft forever
inet6 fe80::42:c3ff:fed8:a148/64 scope link
valid_lft forever preferred_lft forever
7: docker_gwbridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
link/ether 02:42:79:2c:88:0d brd ff:ff:ff:ff:ff:ff
inet 172.18.0.1/16 brd 172.18.255.255 scope global docker_gwbridge
valid_lft forever preferred_lft forever
inet6 fe80::42:79ff:fe2c:880d/64 scope link
valid_lft forever preferred_lft forever
172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0
172.18.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker_gwbridge
Does anyone has similar situation with Docker0 interface and check_mk monitoring?