hostPath

Mounting a hostPath Volume on the Console

You can mount a path on the host to a specified container path. A hostPath volume is usually used to store workload logs permanently or used by workloads that need to access internal data structure of the Docker engine on the host.

1. Log in to the CCE console.
2. When creating a workload, click Data Storage in Container Settings. Click Add Volume and choose hostPath from the drop-down list.
3. Set parameters for adding a local volume, as listed in Table 1.

   Table 1 Setting parameters for mounting a hostPath volume

   Parameter	Description
   Volume Type	Select HostPath.
   HostPath	Path of the host to which the local volume is to be mounted, for example, /etc/hosts. NOTE: HostPath cannot be set to the root directory /. Otherwise, the mounting fails. Mount paths can be as follows: /opt/xxxx (excluding /opt/cloud) /mnt/xxxx (excluding /mnt/paas) /tmp/xxx /var/xxx (excluding key directories such as /var/lib, /var/script, and /var/paas) /xxxx (It cannot conflict with the system directory, such as bin, lib, home, root, boot, dev, etc, lost+found, mnt, proc, sbin, srv, tmp, var, media, opt, selinux, sys, and usr.) Do not set this parameter to /home/paas, /var/paas, /var/lib, /var/script, /mnt/paas, or /opt/cloud. Otherwise, the system or node installation will fail.
   Mount Path	Enter a mount path, for example, /tmp. This parameter indicates the 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, causing container startup failures or workload creation failures. NOTICE: If the container 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.

4. After the configuration, click Create Workload.

Mounting a hostPath Volume Using kubectl

1. Use kubectl to connect to the cluster.
2. Create a file named nginx-hostpath.yaml and edit it.

   vi nginx-hostpath.yaml

   The content of the YAML file is as follows. Mount the /data directory on the node to the /data directory in the container.

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx-hostpath
     namespace: default
   spec:
     replicas: 2
     selector:
       matchLabels:
         app: nginx-hostpath
     template:
       metadata:
         labels:
           app: nginx-hostpath
       spec:
         containers:
           - name: container-1
             image: nginx:latest
             volumeMounts:
               - name: vol-hostpath         # Volume name, which must be the same as the volume name in the volumes field.
                 mountPath: /data           # Mount path in the container.
         imagePullSecrets:
           - name: default-secret
         volumes:
           - name: vol-hostpath             # Volume name, which can be customized.
             hostPath:
               path: /data                  # Directory location on the host node.

3. Create a workload.

   kubectl apply -f nginx-hostpath.yaml