cloud-container-engine/umn/source/workloads/creating_a_daemonset.rst

original_name

cce_10_0216.html

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 CCE Cluster <cce_10_0028>.

Using the CCE Console

1. Log in to the CCE console.

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

3. Set basic information about the workload.

   Basic Info

   • Workload Type: Select DaemonSet. For details about workload types, see Overview <cce_10_0006>.
   • Workload Name: Enter the name of the workload. Enter 1 to 63 characters starting with a lowercase letter and ending with a 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 <cce_10_0278>.
   • Container Runtime: A CCE cluster uses runC by default, whereas a CCE Turbo cluster supports both runC and Kata. For details about the differences between runC and Kata, see Kata Containers and Common Containers <cce_10_0463>.
   • 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 <cce_10_0354>.

   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: See Setting Basic Container Information <cce_10_0396>.

     • Lifecycle: See Setting Container Lifecycle Parameters <cce_10_0105>.

     • Health Check: See Setting Health Check for a Container <cce_10_0112>.

     • Environment Variables: See Setting an Environment Variable <cce_10_0113>.

     • Data Storage: See Overview <cce_10_0307>.

       Note

       If the workload contains more than one pod, EVS volumes cannot be mounted.

     • 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.

     • Logging: See Using ICAgent to Collect Container Logs <cce_10_0018>.

   • 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 <cce_10_0388__section11760122012591>.

   • GPU graphics card: All is selected by default. The workload instance will be scheduled to the node with the specified GPU graphics card type.

   Service Settings

   A Service is used for pod access. With a fixed IP address, a Service forwards access traffic to pods and performs load balancing for these pods.

   You can also create a Service after creating a workload. For details about the Service, see Service Overview <cce_10_0249>.

   Advanced Settings

   • Upgrade: See Configuring the Workload Upgrade Policy <cce_10_0397>.
   • Scheduling: See Scheduling Policy (Affinity/Anti-affinity) <cce_10_0232>.
   • Labels and Annotations: See Pod Labels and Annotations <cce_10_0386>.
   • 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 Tolerations <cce_10_0352__section2047442210417>.
   • DNS: See DNS Configuration <cce_10_0365>.

4. 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.

1. Use kubectl to connect to the cluster. For details, see Connecting to a Cluster Using kubectl <cce_10_0107>.

2. 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.

   The nodeSelector in the preceding pod template specifies that a pod is created only on the nodes that meet daemon=need, as shown in the following figure. If you want to create a pod on each node, delete the label.

3. 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

4. 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

5. If the workload will be accessed through a ClusterIP or NodePort Service, set the corresponding workload access type. For details, see Networking <cce_10_0020>.