tencent cloud

Overview

You can specify the scheduling of the Pods under a workload in the cluster by setting the scheduling policy in the advanced settings of the workload. The following are the typical use cases:

• Run the Pods on a specific node.
• Run the Pods on nodes in a specific scope (which can be an availability zone, a model and so on).

How to Configure Scheduling policies

Prerequisites

• Kubernetes 1.7 or later, and scheduling policies are configured. Scheduling policies can be found under the Advanced Settings of a workload.
• To ensure that your Pods can be scheduled successfully, the node should have resources available for container scheduling after the scheduling policy is configured.
• You need node labels if you use custom scheduling features. For details, refer to Setting Node Label.

Configuring a scheduling policy

If your cluster is created using Kubernetes 1.7 or later, you can set a scheduling policy when creating a workload.
Select one of the following scheduling types:

• Schedule to a specific node: schedule Pods to a specific node with matching node labels.
  
• Custom scheduling: customize how Pods are scheduled by matching Pod labels.
  

Custom scheduling policies have the following modes:

• Conditions that must be met: if a node meets the affinity conditions, the Pods are scheduled to the corresponding node. If not, the scheduling fails.
• Conditions that should be met if possible: if a node meets the affinity conditions, the Pods are scheduled to the corresponding node. If not, the pods are scheduled to a random node.

Multiple custom scheduling policies can be added. The following is a list of operators:

• In: the value of the label is in the list.
• NotIn: the value of the label is not in the list.
• Exists: the key of the label exists.
• DoesNotExits: the key of the label does not exist.
• Gt: the value of the label is greater than the listed value (string match).
• Lt: the value of the label is less than the listed value (string match).

How It Works

Kubernetes uses YAML files to distribute scheduling policies and the affinity and anti-affinity mechanism ensures that Pods are scheduled according to rules. For more information on this mechanism, refer to Kubernetes official documentation.