Creating a DaemonSet

Scenario

CCE provides deployment and management capabilities for multiple types of containers and supports features of container workloads, including creation, configuration, monitoring, scaling, upgrade, uninstall, service discovery, and load balancing.

DaemonSet ensures that only one pod runs on all or some nodes. When a node is added to a cluster, a new pod is also added for the node. When a node is removed from a cluster, the pod is also reclaimed. If a DaemonSet is deleted, all pods created by it will be deleted.

The typical application scenarios of a DaemonSet are as follows:

Run the cluster storage daemon, such as glusterd or Ceph, on each node.
Run the log collection daemon, such as Fluentd or Logstash, on each node.
Run the monitoring daemon, such as Prometheus Node Exporter, collectd, Datadog agent, New Relic agent, or Ganglia (gmond), on each node.

You can deploy a DaemonSet for each type of daemons on all nodes, or deploy multiple DaemonSets for the same type of daemons. In the second case, DaemonSets have different flags and different requirements on memory and CPU for different hardware types.

Prerequisites

You must have one cluster available before creating a DaemonSet. For details on how to create a cluster, see Creating a Cluster.

Using the CCE Console

Log in to the CCE console.
Click the cluster name to go to the cluster console, choose Workloads in the navigation pane, and click Create Workload in the upper right corner.

Set basic information about the workload.

Basic Info

Workload Type: Select DaemonSet. For details about workload types, see Overview.
Workload Name: Enter the name of the workload. Enter 1 to 63 characters starting with a lowercase letter and ending with a lowercase letter or digit. Only lowercase letters, digits, and hyphens (-) are allowed.
Namespace: Select the namespace of the workload. The default value is default. You can also click Create Namespace to create one. For details, see Creating a Namespace.
Time Zone Synchronization: Specify whether to enable time zone synchronization. After time zone synchronization is enabled, the container and node use the same time zone. The time zone synchronization function depends on the local disk mounted to the container. Do not modify or delete the time zone. For details, see Configuring Time Zone Synchronization.

Container Settings

Container Information

Multiple containers can be configured in a pod. You can click Add Container on the right to configure multiple containers for the pod.

Basic Info: Configure basic information about the container.

Parameter	Description
Container Name	Name the container.
Pull Policy	Image update or pull policy. If you select Always, the image is pulled from the image repository each time. If you do not select Always, the existing image of the node is preferentially used. If the image does not exist, the image is pulled from the image repository.
Image Name	Click Select Image and select the image used by the container. To use a third-party image, see Using Third-Party Images.
Image Tag	Select the image tag to be deployed.
CPU Quota	Request: minimum number of CPU cores required by a container. The default value is 0.25 cores. Limit: maximum number of CPU cores available for a container. Do not leave Limit unspecified. Otherwise, intensive use of container resources will occur and your workload may exhibit unexpected behavior. If Request and Limit are not specified, the quota is not limited. For more information and suggestions about Request and Limit, see Setting Container Specifications.
Memory Quota	Request: minimum amount of memory required by a container. The default value is 512 MiB. Limit: maximum amount of memory available for a container. When memory usage exceeds the specified memory limit, the container will be terminated. If Request and Limit are not specified, the quota is not limited. For more information and suggestions about Request and Limit, see Setting Container Specifications.
(Optional) GPU Quota	Configurable only when the cluster contains GPU nodes and the gpu-device-plugin add-on is installed. All: The GPU is not used. Dedicated: GPU resources are exclusively used by the container. Shared: percentage of GPU resources used by the container. For example, if this parameter is set to 10%, the container uses 10% of GPU resources. For details about how to use GPU in the cluster, see Default GPU Scheduling in Kubernetes.
(Optional) Privileged Container	Programs in a privileged container have certain privileges. If Privileged Container is enabled, the container is assigned privileges. For example, privileged containers can manipulate network devices on the host machine and modify kernel parameters.
(Optional) Init Container	Indicates whether to use the container as an init container. The init container does not support health check. An init container is a special container that runs before other app containers in a pod are started. Each pod can contain multiple containers. In addition, a pod can contain one or more Init containers. Application containers in a pod are started and run only after the running of all Init containers completes. For details, see Init Container.

(Optional) Lifecycle: Configure operations to be performed in a specific phase of the container lifecycle, such as Startup Command, Post-Start, and Pre-Stop. For details, see Setting Container Lifecycle Parameters.
(Optional) Health Check: Set the liveness probe, ready probe, and startup probe as required. For details, see Setting Health Check for a Container.
(Optional) Environment Variables: Set variables for the container running environment using key-value pairs. These variables transfer external information to containers running in pods and can be flexibly modified after application deployment. For details, see Setting an Environment Variable.
(Optional) Data Storage: Mount local storage or cloud storage to the container. The application scenarios and mounting modes vary with the storage type. For details, see Storage.
(Optional) Security Context: Set container permissions to protect the system and other containers from being affected. Enter the user ID to set container permissions and prevent systems and other containers from being affected.
(Optional) Logging: Report container stdout streams to AOM by default and require no manual settings. You can manually configure the log collection path. For details, see Using ICAgent to Collect Container Logs.
To disable the standard output of the current workload, add the annotation kubernetes.AOM.log.stdout: [] in Labels and Annotations. For details about how to use this annotation, see Table 1.

Image Access Credential: Select the credential used for accessing the image repository. The default value is default-secret. You can use default-secret to access images in SWR. For details about default-secret, see default-secret.
(Optional) GPU: All is selected by default. The workload instance will be scheduled to the node with the specified GPU graphics card type.

(Optional) Service Settings

A Service provides external access for pods. With a static IP address, a Service forwards access traffic to pods and performs automatic load balancing for these pods.

You can also create a Service after creating a workload. For details about Services of different types, see Overview.

(Optional) Advanced Settings

Upgrade: Specify the upgrade mode and upgrade parameters of the workload. Rolling upgrade and Replace upgrade are supported. For details, see Configuring the Workload Upgrade Policy.

Scheduling: Configure affinity and anti-affinity policies for flexible workload scheduling. Node affinity, pod affinity, and pod anti-affinity are supported. For details, see Scheduling Policy (Affinity/Anti-affinity).

Toleration: Using both taints and tolerations allows (not forcibly) the pod to be scheduled to a node with the matching taints, and controls the pod eviction policies after the node where the pod is located is tainted. For details, see Taints and Tolerations.
Labels and Annotations: Add labels or annotations for pods using key-value pairs. After entering the key and value, click Confirm. For details about how to use and configure labels and annotations, see Labels and Annotations.
DNS: Configure a separate DNS policy for the workload. For details, see DNS Configuration.
Network Configuration:
- Pod ingress/egress bandwidth limitation: You can set ingress/egress bandwidth limitation for pods. For details, see Configuring QoS Rate Limiting for Inter-Pod Access.

Click Create Workload in the lower right corner.

Using kubectl

The following procedure uses Nginx as an example to describe how to create a workload using kubectl.

Use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl.
Create and edit the nginx-daemonset.yaml file. nginx-daemonset.yaml is an example file name, and you can change it as required.

vi nginx-daemonset.yaml

The content of the description file is as follows: The following provides an example. For more information on DaemonSets, see Kubernetes documents.
```
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: nginx-daemonset
  labels:
    app: nginx-daemonset
spec:
  selector:
    matchLabels:
      app: nginx-daemonset
  template:
    metadata:
      labels:
        app: nginx-daemonset
    spec:
      nodeSelector:                 # Node selection. A pod is created on a node only when the node meets daemon=need.
        daemon: need
      containers:
      - name: nginx-daemonset
        image: nginx:alpine
        resources:
          limits:
            cpu: 250m
            memory: 512Mi
          requests:
            cpu: 250m
            memory: 512Mi
      imagePullSecrets:
      - name: default-secret
```
The replicas parameter used in defining a Deployment or StatefulSet does not exist in the above configuration for a DaemonSet, because each node has only one replica. It is fixed.

DaemonSet only creates pods on nodes with specific labels. In the preceding pod template, nodeSelector specifies that a pod is created only on nodes with the daemon: need label. If you want to create a pod on each node, delete the label.
Create a DaemonSet.

kubectl create -f nginx-daemonset.yaml

If the following information is displayed, the DaemonSet is being created.
```
daemonset.apps/nginx-daemonset created
```

Query the DaemonSet status.

kubectl get ds

$ kubectl get ds
NAME              DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
nginx-daemonset   1         1         0       1            0           daemon=need     116s