Continental Innovates with Rancher and Kubernetes
When you create a cluster, some alert rules are predefined. These alerts notify you about signs that the cluster could be unhealthy. You can receive these alerts if you configure a notifier for them.
Several of the alerts use Prometheus expressions as the metric that triggers the alert. For more information on how expressions work, you can refer to the Rancher documentation about Prometheus expressions or the Prometheus documentation about querying metrics.
Etcd is the key-value store that contains the state of the Kubernetes cluster. Rancher provides default alerts if the built-in monitoring detects a potential problem with etcd. You don’t have to enable monitoring to receive these alerts.
A leader is the node that handles all client requests that need cluster consensus. For more information, you can refer to this explanation of how etcd works.
The leader of the cluster can change in response to certain events. It is normal for the leader to change, but too many changes can indicate a problem with the network or a high CPU load. With longer latencies, the default etcd configuration may cause frequent heartbeat timeouts, which trigger a new leader election.
Rancher provides alerts when core Kubernetes system components become unhealthy.
Controllers update Kubernetes resources based on changes in etcd. The controller manager monitors the cluster desired state through the Kubernetes API server and makes the necessary changes to the current state to reach the desired state.
The scheduler service is a core component of Kubernetes. It is responsible for scheduling cluster workloads to nodes, based on various configurations, metrics, resource requirements and workload-specific requirements.
Kubernetes events are objects that provide insight into what is happening inside a cluster, such as what decisions were made by the scheduler or why some pods were evicted from the node. In the Rancher UI, from the project view, you can see events for each workload.
Alerts can be triggered based on node metrics. Each computing resource in a Kubernetes cluster is called a node. Nodes can be either bare-metal servers or virtual machines.
When you enable monitoring for the project, some project-level alerts are provided. For details, refer to the section on project-level alerts.