Optimization of kubeedge deployment documentation: Handling issues with insufficient edge node resources for normal deployment.

docs/advanced/image-prepull.md

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+---
+title: KubeEdge Image PrePull Feature Guide Document
+sidebar_position: 6
+---
+
+
+# KubeEdge Image PrePull Feature Guide Document
+
+KubeEdge version 1.16 introduces a new feature called Image Pre-Pull, which allows users to load images ahead of time on edge nodes through the Kubernetes API of ImagePrePullJob. This feature supports pre-pull multiple images in batches across multiple edge nodes or node groups, helping to reduce the failure rates and inefficiencies associated with loading images during application deployment or updates, especially in large-scale scenarios.
+
+API example for ImagePrePullJob：
+
+```
+apiVersion: operations.kubeedge.io/v1alpha1
+kind: ImagePrePullJob
+metadata:
+  name: imageprepull-example
+  labels:
+    description: ImagePrePullLabel
+spec:
+  imagePrePullTemplate：
+    images:
+      - image1
+      - image2
+    nodes：
+      - edgenode1
+      - edgenode2
+    checkItems:
+      - "disk"
+    failureTolerate: "0.3"
+    concurrency: 2
+    timeoutSeconds: 180
+    retryTimes: 1
+
+```
+
+
+## 1. Preparation
+
+**Example：Nginx Demo**
+
+Nginx is a lightweight image that allows users to demonstrate it without any prerequisite environment. Nginx image will be uploaded to a private image repository in advance. Users can call the pre-pull function API from the cloud to pre-pull the Nginx image to edge nodes from the private image repository.
+
+**1）This example requires KubeEdge version to be v1.16.0 or above, and Kubernetes version to be v1.27.0 or above. The selected version is KubeEdge v1.16.0 and Kubernetes version is v1.27.3.**
+
+```
+[root@ke-cloud ~]# kubectl get node
+NAME            STATUS    ROLES                  AGE   VERSION
+cloud.kubeedge   Ready    control-plane,master   3d   v1.27.3
+edge.kubeedge    Ready    agent,edge             2d   v1.27.7-kubeedge-v1.16.0
+
+Note: The following operations will use the edge node edge.kubeedge. If you refer to this document for related operations, the configuration of the edge node name in subsequent steps needs to be changed according to your actual situation.
+```
+
+**2）Ensure that the CloudCore has the following configuration enabled**
+
+
+```
+      taskManager:
+        enable: true  // Change from false to true
+```
+changes can be made by editing the file kubectl edit configmap cloudcore -n kubeedge with commands, and restarting the cloudcore component of the K8s apiserver.
+
+
+
+
+## 2. Prepare the Secret for the privare image (optional)
+Here is a private image repository prepared for demonstration purposes using Alibaba Cloud's registry URL: registry.cn-hangzhou.aliyuncs.com. The demo space used is jilimoxing, and modifications may be necessary based on actual circumstances during the actual operation.
+
+**1）Pushing nginx into the private image repository**
+
+```
+[root@cloud ~]# docker tag nginx registry.cn-hangzhou.aliyuncs.com/jilimoxing/test:nginx
+[root@cloud crds~]# docker push registry.cn-hangzhou.aliyuncs.com/jilimoxing/test:nginx
+```
+
+**2）Create a Secret on the cloud**
+Secret is not a required field in ImagePrePullJob. If you need to prepull private image, you can generate a secret for it.
+You can also use kubectl to create a Secret for accessing a container registry,such as when you don`t have a Docker configuration file:
+
+```
+[root@cloud ~]# kubectl create secret docker-registry my-secret \
+  [email protected] \
+  --docker-username=tiger \
+  --docker-password=pass1234 \
+  --docker-email=my-registry.example:5000
+
+[root@cloud ~]# kubectl get secret -A
+NAMESPACE   NAME             TYPE                             DATA   AGE
+default     my-secret         kubernetes.io/dockerconfigjson   1      31s
+
+```
+
+## 3. Create Yaml File
+
+**1）Modify Code**
+
+To create a yaml file on a cloud node, you need to modify the corresponding images information and imageSecrets information to keep them consistent with the pre-pull image repository secret. The information should be as follows:
+```
+
+[root@ke-cloud ~]# vim imageprepull.yaml
+
+apiVersion: operations.kubeedge.io/v1alpha1
+kind: ImagePrePullJob
+metadata:
+  name: imageprepull-example
+spec:
+  imagePrePullTemplate:
+    concurrency: 1
+    failureTolerate: '0.1'
+    images:
+      - registry.cn-hangzhou.aliyuncs.com/jilimoxing/test:nginx
+    nodeNames:
+      - edge.kubeedge
+    imageSecrets: default/my-secret
+    retryTimes: 1
+    timeoutSeconds: 120
+
+```
+
+**2）executable file**
+
+
+```
+[root@ke-cloud ~]# kubectl apply -f imageprepull.yaml
+```
+
+
+**3) Get ImagePrepulljob Status**
+
+use：kubectl get imageprepulljobs.operations.kubeedge.io imageprepull-example -o jsonpath='{.status}'
+
+```
+[root@ke-cloud ~]# kubectl get imageprepulljobs.operations.kubeedge.io imageprepull-example -o jsonpath='{.status}'
+[root@ke-cloud ~]# {"action":"Success","event":"Pull","state":"Successful","status":[{"imageStatus":[{"image":"registry.cn-hangzhou.aliyuncs.com/jilimoxing/test:nginx","state":"Successful"}],"nodeStatus":{"action":"Success","event":"Pull","nodeName":"edge.kubeedge","state":"Successful","time":"2024-04-26T18:51:41Z"}}],"time":"2024-04-26T18:51:41Z"}
+```
+
+## 4. Check if the edge node image has been pre-pull successfully
+
+Enter the edge terminal and use the command ctr -n k8s.io i ls to view.
+```
+[root@edge ~]# ctr -n k8s.io i ls
+```
+The corresponding image has been successfully pre-pull.
+```
+REF                                                        TYPE                                                      DIGEST                                                                  SIZE      PLATFORMS                                                                    LABELS                                                          
+registry.cn-hangzhou.aliyuncs.com/jilimoxing/test:nginx    application/vnd.docker.distribution.manifest.v2+json      sha256:73e957703f1266530db0aeac1fd6a3f87c1e59943f4c13eb340bb8521c6041d7 67.3 MiB  linux/amd64 
+```
+