Node Network Bridge Down

Summary: A Linux bridge is no longer reporting traffic.

Consequences: If the bridge is being used by processes to send/receive traffic, those processes are effectively cut off from the network. This ranges from fine to very bad, depending on the process/service.

Possible causes

A Docker network was deleted: if a Docker network was deleted or recreated recently, this alert can fire, because Linux typically creates a bridge for each Docker network. The bridge name will include part of the Docker network ID if this is the case. Typically this is benign if this is the cause.

Network is misconfigured: it is likely that, if this is a major/primary network bridge, then all connectivity is down (though a NodeExporterDown alert would be expected in that case, as the monitoring infrastructure likely wouldn't be able to get this information from the problem host at all!).

OVS bridges were deleted: this can happen during an upgrade, but shouldn't persist for very long. It may be necessary to repair OVS state. Try running ./cc-ansible reconfigure --tags openvswitch to fix.