Container Service for Kubernetes:Best practices for node pool deployment sets

Feature usage notes in clusters

• Deployment sets support only ACK managed clusters and ACK dedicated clusters.

• You can specify a deployment set only when creating a new node pool. You cannot enable it for an existing node pool. Each node pool supports binding to only one deployment set.

• You cannot manually add or remove nodes from a deployment set. Adjust the number of nodes in the deployment set by scaling the node pool. For more information, see Create and manage node pools.

• After enabling deployment sets, you cannot create spot instances.

Deployment set quotas and instance type limits

• Deployment set quota limits:

  • By default, node pool deployment sets use the high availability policy. Under this policy, you can create up to 20 ECS instances per zone within a deployment set. The total number of ECS instances you can create in an Alibaba Cloud region is 20 × number of zones. Ensure sufficient ECS instance quotas and adequate inventory for your required instance types in the deployment set. For more information, see Deployment sets.

    The maximum number of instances allowed in a single deployment set cannot be increased. However, to raise the maximum number of deployment sets allowed for your account, apply through the Quota Center. For more information about deployment set limits and quotas, see Limits on deployment sets.

  • If creating an ECS instance in a deployment set fails, or if restarting a pay-as-you-go ECS instance (in economical mode) fails, the cause may be insufficient inventory in the region. Wait a while and retry creating or restarting the instance.

• Instance family restrictions: Most instance families of generation 6 and later support deployment sets with the High Availability strategy, High Availability Group strategy, and Low Latency strategy.

  Different deployment strategies support only specific instance families:

  For the definitive list of supported instance families, refer to the output of the DescribeDeploymentSetSupportedInstanceTypeFamily operation.

  Deployment strategy	Supported instance families
  High Availability strategy and High Availability Group strategy	g9a, g9ae, g9i, g8a, g8i, g8ine, g8ise, g8y, g7, g7a, g7h, g7ne, g7nex, g7se, g7t, g6, g6a, g6e, g6h, g5, g5ne c9a, c9ae, c9i, c8a, c8i, c8ine, c8y, c7, c7a, c7nex, c7se, c7t, c6, c6a, c6e, c5 r9a, r9ae, r9i, r8a, r8i, r8y, r7, r7a, r7se, r7t, r6, r6a, r6e, r5 hfc9i, hfg9i, hfr9i, hfc8i, hfg8i, hfr8i, hfc7, hfg7, hfr7, hfc6, hfg6, hfr6, hfc5, hfg5 ebmc9i, ebmg9a, ebmg9i, ebmr9i, ebmc8a, ebmc8i, ebmc8y, ebmg8a, ebmg8i, ebmg8y, ebmr8a, ebmr8y, ebmc7, ebmc7a, ebmg7, ebmg7a, ebmg7se, ebmhfc7, ebmhfg7, ebmhfr7, ebmr7, ebmr7a, ebmg5 i5, i5g, i5ge, ic5, i4, i4g, i4r, i3, i3g, i2, i2g, i2gne, i2ne gn6i d3c, d3s, d2c, d2s, d1ne re6, re6p, s6, t6, e4, mn4, n4, re4, xn4, sn2ne, u2a, u2i, se1, se1ne, sn1ne, u1, e
  Low Latency strategy	g9a, g9ae, g9i, g8a, g8ae, g8i, g8ise, g8y, g7, g5ne c9a, c9ae, c9i, c8a, c8ae, c8i, c8ine, c8y, c7, c7nex r9a, r9ae, r9i, r8a, r8ae, r8i, r8y, r7 hfc9i, hfg9i, hfr9i, hfc8i, hfg8i, hfr8i ebmc9i, ebmg9a, ebmg9i, ebmr9i, ebmc8a, ebmc8i, ebmc8y, ebmg8a, ebmg8i, ebmg8y, ebmgn8v, ebmr8a, ebmr8y, ebmc7, ebmc7a, ebmg7, ebmg7a, ebmg7se, ebmgn7ex, ebmhfc7, ebmhfg7, ebmhfr7, ebmr7, ebmr7a i5, i5g, i5ge, i4 gn8v hpc8ae, hpc8i, hpc7ip, hpc6id, u2a, u2i

Schedule pods from the same workload in a single node pool so that only one pod runs per node using pod anti-affinity

This example shows how to schedule three pod replicas from a Deployment onto three different nodes. Follow these steps.

1. Create a node pool with three nodes and assign a deployment set ID to the node pool. For more information, see Assign a deployment set to a node pool in the console.

   After creating the node pool, go to the Node Pools page, click the target node pool, and then on the Nodes tab, verify that three nodes were created successfully.

   Log on to the ECS console. In the navigation pane on the left, choose Deployment & Elasticity > Deployment Set. On the Deployment Set page, confirm that all three nodes in the node pool belong to the selected deployment set.

2. Use the following YAML to configure your application.

   Configure pod anti-affinity to schedule the three application pods onto different nodes in the node pool.

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx
     labels:
       app: nginx
   spec:
     replicas: 3
     selector:
       matchLabels:
         app: nginx
     template:
       metadata:
         name: nginx
         labels:
           app: nginx
       spec:
         affinity:
           podAntiAffinity:
             requiredDuringSchedulingIgnoredDuringExecution:  # Set the scheduling policy.
             - labelSelector:
                 matchExpressions:
                 - key: app
                   operator: In
                   values:
                   - nginx
               topologyKey: kubernetes.io/hostname
         nodeSelector:
             alibabacloud.com/nodepool-id: <nodepool-id>  # Specify the node pool ID.
         containers:
         - name: nginx
           image: anolis-registry.cn-zhangjiakou.cr.aliyuncs.com/openanolis/nginx:1.14.1-8.6
           resources:
             limits:
               cpu: 1
             requests:
               cpu: 1

   Execution Result

   On the Deployments page, click the target Deployment. On the Pods tab, you can see that the three pods are scheduled onto different nodes in the node pool.

Distribute pods from the same workload evenly across zones and nodes within a single node pool

1. Create a node pool with four nodes, assign a deployment set ID to the node pool, and select vSwitches in multiple zones. For more information, see Assign a deployment set to a node pool in the console.

   After creation, go to the Node Pools page, click the target node pool, and then on the Nodes tab, verify that four nodes exist across four zones. Based on ESS’s even distribution policy, the created ECS instances are spread across four different zones and all belong to the deployment set.

   Log on to the ECS console. In the navigation pane on the left, choose Deployment & Elasticity > Deployment Set. On the Deployment Set page, confirm that all four nodes in the node pool belong to the selected deployment set.

2. Use the following YAML to configure your application.

   Use pod topology spread constraints to distribute pods from the same application evenly across zones and nodes. For more information, see Pod topology spread constraints.

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx
     labels:
       app: nginx
   spec:
     replicas: 4
     selector:
       matchLabels:
         app: nginx
     template:
       metadata:
         name: nginx
         labels:
           app: nginx
       spec:
         topologySpreadConstraints:
           - maxSkew: 1
             topologyKey: kubernetes.io/hostname
             whenUnsatisfiable: DoNotSchedule
             labelSelector:
               matchLabels:
                 app: nginx
           - maxSkew: 1
             topologyKey: topology.kubernetes.io/zone
             whenUnsatisfiable: DoNotSchedule
             labelSelector:
               matchLabels:
                 app: nginx
         nodeSelector:
           alibabacloud.com/nodepool-id: <nodepool-id>  # Specify the node pool ID.
         containers:
         - name: nginx
           image: anolis-registry.cn-zhangjiakou.cr.aliyuncs.com/openanolis/nginx:1.14.1-8.6
           resources:
             limits:
               cpu: 1
             requests:
               cpu: 1

   Execution Result

   On the Deployments page, click the target Deployment. On the Pods tab, you can see that pods from the same application are evenly distributed across zones and nodes.