Configure DaemonSet update models to address DaemonSet update issues and enable OTA updates - Container Service for Kubernetes

The cloud-native rolling update model cannot meet the requirement for application updates in cloud-edge collaboration scenarios. For example, when the edge network disconnects from the cloud, DaemonSet rolling updates may become stuck due to nodes in the NotReady state. You may also need to trigger rolling updates on edge nodes in scenarios such as over-the-air (OTA) updates for green vehicles. To address the preceding issues, the AdvancedRollingUpdate and OTA update models are introduced.

Prerequisites

The DaemonSet update models are supported by ACK Edge clusters that run Kubernetes 1.26.3-aliyun.1.

DaemonSet update models

AdvancedRollingUpdate
You can use this update model to address the issue that DaemonSet updates become stuck due to nodes in the NotReady state. During the update process, this model updates nodes in the Ready state first and skips nodes in the NotReady state. After the status of a node changes from NotReady to Ready, DaemonSet pods on the node are automatically updated.
OTA
This update model allows you to call REST APIs on edge nodes to check whether the pods are updatable and trigger pod updates.

Configure update models

apiVersion: apps/v1
kind: DaemonSet
metadata:
  annotations:
    apps.openyurt.io/update-strategy: AdvancedRollingUpdate
    apps.openyurt.io/max-unavailable: 30%
spec:
  updateStrategy:
    type: OnDelete

Parameter	Description
apps.openyurt.io/update-strategy	Enable update model extensions. Valid values: AdvancedRollingUpdate and OTA.
apps.openyurt.io/max-unavailable	This parameter takes effect only when you enable the `AdvancedRollingUpdate` model. This parameter specifies the maximum number of unavailable pods during the update process when the AdvancedRollingUpdate update model is used. The value must be the same as the value of the `maxUnavailable` parameter of the DaemonSet that you want to update. Default value: `10%`.
DaemonSet.spec.updateStrategy.type	Set the value to `OnDelete`. You must manually delete pods before pods that run the new version can be created.

Use the update models

AdvancedRollingUpdate

The following code block provides an example on how to create a DaemonSet named nginx-daemonset and enable the AdvancedRollingUpdate update model for the DaemonSet. During a rolling update, at most 30% of the DaemonSet pods can be unavailable. The following code is an example:

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: nginx-daemonset
  annotations:
    apps.openyurt.io/update-strategy: AdvancedRollingUpdate
    apps.openyurt.io/max-unavailable: 30%
spec:
  selector:
    matchLabels:
      app: nginx
  updateStrategy:
    type: OnDelete
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.19.4
EOF

OTA

REST APIs for OTA updates
The edge-hub components on an edge node can call the following REST APIs to enable OTA updates:
- GET /pods
  This REST API is used to query information about pods on the node. The PodNeedUpgrade parameter in the Pod.status.conditions section of the response indicates whether the pods are updatable.
- POST /openyurt.io/v1/namespaces/{ns}/pods/{podname}/upgrade
  This REST API is used to trigger an update for a specified DaemonSet pod. You can configure the {ns} and {podname} parameters to specify the pod that you want to update. This allows you to update individual pods based on your business requirements.

Use case of the OTA update model

Create a DaemonSet named nginx-daemonset and enable the OTA update model for the DaemonSet. When the image used by the DaemonSet is updated, the DaemonSet pods are not automatically updated. You need to call REST APIs on edge nodes to check whether the pods are updatable and trigger updates.

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: nginx-daemonset
  annotations:
    apps.openyurt.io/update-strategy: OTA
spec:
  selector:
    matchLabels:
      app: nginx
  updateStrategy:
    type: OnDelete
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.19.4

EOF

Use case of the OTA update model
1. Log on to an edge node and run the following command to to check for any pods that require updates on the node:
```
curl http://127.0.0.1:10267/pods
```
  If `PodNeedUpgrade=true` is displayed in the default/nginx-daemonset-bwzss pod.Status.Conditions field in the output, the pod requires an update.
2. Run the following command to update the pod:
```
curl -X POST http://127.0.0.1:10267/openyurt.io/v1/namespaces/default/pods/nginx-daemonset-bwzss/upgrade
```
3. Run the following command to update the DaemonSet configuration:
```
Start updating pod default/nginx-daemonset-bwzss
```

References

For more information about how to check the pod status, see Manage pods.