Cloud-Init Configuration FAQ

How Do I Change the Hostname of a Cloud Server?

1. When creating a cloud server, in the Advanced Options area, click Configure now and paste the following content to the User Data text box:

   #cloud-config

   hostname: zt.cloud-init.test

   manage_etc_hosts: true

   

   Note

   Cloud-Init can read only the data starting with #cloud-config.

2. Log in to the cloud server and run the following command to check whether the hostname has been changed:

   cat /etc/hosts

   If the new hostname (zt.cloud-init.test) is displayed in the command output, the hostname has been changed.

   

How Do I Configure an SSH Key for a Cloud Server and Use Cloud-Init to Add a User?

1. Remotely log in to the cloud server in SSH mode.

   vim /etc/ssh/sshd_config

   PasswordAuthentication: yes

2. Generate a key pair.

   ssh-keygen -t rsa -f ~/.ssh/id_rsa -P

   cat ~/.ssh/id_rsa.pub

   Example:

   #cloud-config
   users:
     - default
     - name: myadminuser
       groups: sudo
       shell: /bin/bash
       sudo: ['ALL=(ALL) NOPASSWD:ALL']
       ssh-authorized-keys:
             - ssh-rsa Public key (for example, ~/.ssh/id_rsa.pub)
   
   

   Note

   • If the #cloud-config script contains the - default parameter, the new user will be added to the administrator list.
   • If the #cloud-config script does not contain the - default parameter, the new user will overwrite the original administrator.
3. Log in to the cloud server in SSH mode.

   ssh <user>@<publicIpAddress>

4. Open the /etc/group file and check whether the user is added to the cloud server and the specified user group:

   cat /etc/group

5. If the following information is displayed, the user in the cloud_init_add_user.txt file has been added to the cloud server and the specified user group:

   root:x:0:

   <snip />

   sudo:x:27:myadminuser

How Do I Create a Swap Partition?

Cloud-Init can be used to create swap partitions in Linux distributions. Conventionally, swap partitions are configured by the Linux agent (WALA) for different distributions. The following describes how to use Cloud-Init to create a swap partition.

1. Use Cloud-Init to create two partitions on a temporary disk. The first partition occupies 66% of the disk space. By default, it is an ext4 partition and is mounted to /mnt. The second partition is a swap partition, which occupies the remaining disk space and takes effect when the cloud server is started.

   #cloud-config    
   disk_setup: # Disk settings
     ephemeral0:
       table_type: mbr (mbr or gpt)
       layout: [66, [33, 82]]  # 82 indicates the disk type of a swap partition.
       overwrite: True
   fs_setup:    # Configure a file system on the partition.
     - device: ephemeral0.1
       filesystem: ext4
     - device: ephemeral0.2
       filesystem: swap
   mounts:   # Use the first partition as ext4 and the second as swap.
     - ["ephemeral0.1", "/mnt"]
     - ["ephemeral0.2", "none", "swap", "sw", "0", "0"]
   
   

2. Check whether the swap partition is successfully created.

   swapon -s

   If the following information is displayed, the swap partition is successfully created: