Network Checker Application

With the deploy_netchecker var enabled (defaults to false), Kubespray deploys a Network Checker Application from the 3rd side l23network/k8s-netchecker docker images. It consists of the server and agents trying to reach the server by usual for Kubernetes applications network connectivity meanings. Therefore, this automatically verifies a pod to pod connectivity via the cluster IP and checks if DNS resolve is functioning as well.

The checks are run by agents on a periodic basis and cover standard and host network pods as well. The history of performed checks may be found in the agents’ application logs.

To get the most recent and cluster-wide network connectivity report, run from any of the cluster nodes:

  1. curl http://localhost:31081/api/v1/connectivity_check

Note that Kubespray does not invoke the check but only deploys the application, if requested.

There are related application specific variables:

  1. netchecker_port: 31081
  2. agent_report_interval: 15
  3. netcheck_namespace: default

Note that the application verifies DNS resolve for FQDNs comprising only the combination of the netcheck_namespace.dns_domain vars, for example the netchecker-service.default.svc.cluster.local. If you want to deploy the application to the non default namespace, make sure as well to adjust the searchdomains var so the resulting search domain records to contain that namespace, like:

  1. search: foospace.cluster.local default.cluster.local ...
  2. nameserver: ...