MachineHealthCheck

MachineHealthCheck Support

Provider support details

You can configure EKS Anywhere to specify timeouts and maxUnhealthy values for machine health checks.

A MachineHealthCheck (MHC) is a resource in Cluster API which allows users to define conditions under which Machines within a Cluster should be considered unhealthy. A MachineHealthCheck is defined on a management cluster and scoped to a particular workload cluster.

Note: Even though the MachineHealthCheck configuration in the EKS-A spec is optional, MachineHealthChecks are still installed for all clusters using the default values mentioned below.

EKS Anywhere allows users to have granular control over MachineHealthChecks in their cluster configuration, with default values (derived from Cluster API) being applied if the MHC is not configured in the spec. The top-level machineHealthCheck field governs the global MachineHealthCheck settings for all Machines (control-plane and worker). These global settings can be overridden through the nested machineHealthCheck field in the control plane configuration and each worker node configuration. If the nested MHC fields are not configured, then the top-level settings are applied to the respective Machines.

The following cluster spec shows an example of how to configure health check timeouts and maxUnhealthy:

apiVersion: anywhere.eks.amazonaws.com/v1alpha1
kind: Cluster
metadata:
   name: my-cluster-name
spec:
   ...
  machineHealthCheck:               # Top-level MachineHealthCheck configuration
    maxUnhealthy: "60%"
    nodeStartupTimeout: "10m0s"
    unhealthyMachineTimeout: "5m0s"
   ...
 controlPlaneConfiguration:         # MachineHealthCheck configuration for Control plane
    machineHealthCheck:
      maxUnhealthy: 100%
      nodeStartupTimeout: "15m0s"
      unhealthyMachineTimeout: 10m
   ...
  workerNodeGroupConfigurations:
  - count: 1
    name: md-0
    machineHealthCheck:             # MachineHealthCheck configuration for Worker Node Group 0
      maxUnhealthy: 100%
      nodeStartupTimeout: "10m0s"
      unhealthyMachineTimeout: 20m
  - count: 1
    name: md-1
    machineHealthCheck:             # MachineHealthCheck configuration for Worker Node Group 1
      maxUnhealthy: 100%
      nodeStartupTimeout: "10m0s"
      unhealthyMachineTimeout: 20m
   ...

MachineHealthCheck Spec Details

machineHealthCheck (optional)

• Description: top-level key; required to configure global MachineHealthCheck timeouts and maxUnhealthy.
• Type: object

machineHealthCheck.maxUnhealthy (optional)

• Description: determines the maximum permissible number or percentage of unhealthy Machines in a cluster before further remediation is prevented. This ensures that MachineHealthChecks only remediate Machines when the cluster is healthy.
• Default: 100% for control plane machines, 40% for worker nodes (Cluster API defaults).
• Type: integer (count) or string (percentage)

machineHealthCheck.nodeStartupTimeout (optional)

• Description: determines how long a MachineHealthCheck should wait for a Node to join the cluster, before considering a Machine unhealthy.
• Default: 20m0s for Tinkerbell provider, 10m0s for all other providers.
• Minimum Value (If configured): 30s
• Type: string

machineHealthCheck.unhealthyMachineTimeout (optional)

• Description: determines how long the unhealthy Node conditions (e.g., Ready=False, Ready=Unknown) should be matched for, before considering a Machine unhealthy.
• Default: 5m0s
• Type: string

controlPlaneConfiguration.machineHealthCheck (optional)

• Description: Control plane level configuration for MachineHealthCheck timeouts and maxUnhealthy values.
• Type: object

controlPlaneConfiguration.machineHealthCheck.maxUnhealthy (optional)

• Description: determines the maximum permissible number or percentage of unhealthy control plane Machines in a cluster before further remediation is prevented. This ensures that MachineHealthChecks only remediate Machines when the cluster is healthy.
• Default: Top-level MHC maxUnhealthy if set or 100% otherwise.
• Type: integer (count) or string (percentage)

controlPlaneConfiguration.machineHealthCheck.nodeStartupTimeout (optional)

• Description: determines how long a MachineHealthCheck should wait for a control plane Node to join the cluster, before considering the Machine unhealthy.
• Default: Top-level MHC nodeStartupTimeout if set or 20m0s for Tinkerbell provider, 10m0s for all other providers otherwise.
• Minimum Value (if configured): 30s
• Type: string

controlPlaneConfiguration.machineHealthCheck.unhealthyMachineTimeout (optional)

• Description: determines how long the unhealthy conditions (e.g., Ready=False, Ready=Unknown) should be matched for a control plane Node, before considering the Machine unhealthy.
• Default: Top-level MHC nodeStartupTimeout if set or 5m0s otherwise.
• Type: string

workerNodeGroupConfigurations.machineHealthCheck (optional)

• Description: Worker node level configuration for MachineHealthCheck timeouts and maxUnhealthy values.
• Type: object

workerNodeGroupConfigurations.machineHealthCheck.maxUnhealthy (optional)

• Description: determines the maximum permissible number or percentage of unhealthy worker Machines in a cluster before further remediation is prevented. This ensures that MachineHealthChecks only remediate Machines when the cluster is healthy.
• Default: Top-level MHC maxUnhealthy if set or 40% otherwise.
• Type: integer (count) or string (percentage)

workerNodeGroupConfigurations.machineHealthCheck.nodeStartupTimeout (optional)

• Description: determines how long a MachineHealthCheck should wait for a worker Node to join the cluster, before considering the Machine unhealthy.
• Default: Top-level MHC nodeStartupTimeout if set or 20m0s for Tinkerbell provider, 10m0s for all other providers otherwise.
• Minimum Value (if configured): 30s
• Type: string

workerNodeGroupConfigurations.machineHealthCheck.unhealthyMachineTimeout (optional)

• Description: determines how long the unhealthy conditions (e.g., Ready=False, Ready=Unknown) should be matched for a worker Node, before considering the Machine unhealthy.
• Default: Top-level MHC nodeStartupTimeout if set or 5m0s otherwise.
• Type: string