kubespray 2.24 추가

docs/netcheck.md

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+# Network Checker Application
+
+With the ``deploy_netchecker`` var enabled (defaults to false), Kubespray deploys a
+Network Checker Application from the 3rd side `mirantis/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:
+
+```ShellSession
+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:
+
+```yml
+netchecker_port: 31081
+agent_report_interval: 15
+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:
+
+```yml
+search: foospace.cluster.local default.cluster.local ...
+nameserver: ...
+```