Network checker overview¶

Network checker, or Netchecker, is a Kubernetes application that verifies connectivity between the Kubernetes nodes.

Netchecker comprises the following components:

• Netchecker agent is deployed on every Kubernetes node using the Daemonset mechanism which ensures automatic pod management. Agents periodically gather networking information from the Kubernetes nodes and send it to the Netchecker server.
• Netchecker server is deployed in a dedicated Kubernetes pod and exposed inside of the cluster through the Kubernetes service resource. All Netchecker agents connect to the Netchecker server through the service DNS name.

The communication mechanism between the user and Netchecker is the HTTP RESTful interface. You can run the following requests:

• GET - /api/v1/connectivity_check - request to test the connectivity between the Netchecker server and agents. The response contains information about possible issues.

  Example of the request:

  curl http://nc-server-ip:port/api/v1/connectivity_check
  

  This request returns the following:

  Message	A text that describes the status of the connection between the agent and server pods. Example: All 4 pods successfully reported back to the server.
  Absent	Indicates that the Netchecker server failed to receive reports from one or more Netchecker agents since the deployment of the Netchecker application. This field can be empty.
  Outdated	Indicates that the Netchecker server failed to receive reports from one or more agents within the configured report interval due to a connectivity error. This field can be empty.

The following diagram illustrates how the Netchecker works: