Help Center/ Cloud Container Engine/ User Guide/ Storage/ Ephemeral Volumes/ Using a Temporary Path
Updated on 2024-08-16 GMT+08:00
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Using a Temporary Path

A temporary path is of the Kubernetes-native emptyDir type. Its lifecycle is the same as that of a pod. Memory can be specified as the storage medium. When the pod is deleted, the emptyDir volume is deleted and its data is lost.

Using a Temporary Path on the Console

  1. Log in to the CCE console and click the cluster name to access the cluster console.
  2. Choose Workloads in the navigation pane. In the right pane, click the Deployments tab.
  3. Click Create Workload in the upper right corner. On the displayed page, click Data Storage in the Container Settings area and click Add Volume to select EmptyDir.
  4. Mount and use storage volumes, as shown in Table 1. For details about other parameters, see Workloads.

    Table 1 Mounting an EV

    Parameter

    Description

    Storage Medium
    Memory:
    • You can select this option to improve the running speed, but the storage capacity is subject to the memory size. This mode is applicable when data volume is small and efficient read and write is required.
    • If this function is disabled, data is stored in hard disks, which applies to a large amount of data with low requirements on reading and writing efficiency.
    NOTE:
    • If Memory is selected, pay attention to the memory size. If the storage capacity exceeds the memory size, an OOM event occurs.
    • If Memory is selected, the size of an EV is the same as pod specifications.
    • If Memory is not selected, EVs will not occupy the system memory.

    Mount Path

    Enter a mount path, for example, /tmp.

    This parameter specifies a container path to which a data volume will be mounted. Do not mount the volume to a system directory such as / or /var/run. Otherwise, containers will be malfunctional. Mount the volume to an empty directory. If the directory is not empty, ensure that there are no files that affect container startup. Otherwise, the files will be replaced, leading to container startup failures or workload creation failures.
    NOTICE:

    If a volume is mounted to a high-risk directory, use an account with minimum permissions to start the container. Otherwise, high-risk files on the host may be damaged.

    Subpath

    Enter the subpath of the storage volume and mount a path in the storage volume to the container. In this way, different folders of the same storage volume can be used in a single pod. tmp, for example, indicates that data in the mount path of the container is stored in the tmp folder of the storage volume. If this parameter is left blank, the root path is used by default.

    Permission
    • Read-only: You can only read the data in the mounted volumes.
    • Read-write: You can modify the data volumes mounted to the path. Newly written data will not be migrated if the container is migrated, which may cause data loss.

  5. After the configuration, click Create Workload.

Using a Temporary Path Through kubectl

  1. Use kubectl to access the cluster. For details, see Connecting to a Cluster Using kubectl.
  2. Create a file named nginx-emptydir.yaml and edit it.

    vi nginx-emptydir.yaml

    Content of the YAML file:

    apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-emptydir
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx-emptydir
  template:
    metadata:
      labels:
        app: nginx-emptydir
    spec:
      containers:
        - name: container-1
          image: nginx:latest
          volumeMounts:
            - name: vol-emptydir     # Volume name, which must be the same as the volume name in the volumes field
              mountPath: /tmp        # Location where the emptyDir is mounted
      imagePullSecrets:
        - name: default-secret
      volumes:
        - name: vol-emptydir         # Volume name, which can be customized
          emptyDir:
            medium: Memory          # EV disk medium: If this parameter is set to Memory, the memory is enabled. If this parameter is left blank, the native default storage medium is used.
            sizeLimit: 1Gi          # Volume capacity

  3. Create a workload.

    kubectl apply -f nginx-emptydir.yaml

Parent Topic: Ephemeral Volumes