Forcibly Import Image

Last updated: 2020-04-27 14:46:37

    Scenario

    If you cannot install cloudinit in your Linux image, use Forced Image Import to import the image. If you use this image for import, which does not have cloudinit installed, Tencent Cloud cannot initialize your CVM. In this case, you need to set up the script on your own to configure the CVM based on the configuration file provided by Tencent Cloud. This document describes how to configure the CVM if the image is forcibly imported.

    Tencent Cloud provides the user with CDROM device containing the configuration information. The user needs to mount CDROM and read the information of mount_point/qcloud_action/os.conf for configuration. If other configuration data or UserData needs to be used, the user can directly read files under mount_point/.

    os.conf Configuration File

    The content of os.conf is as follows.

    hostname=VM_10_20_xxxx
    password=GRSgae1fw9frsG.rfrF
    eth0_ip_addr=10.104.62.201
    eth0_mac_addr=52:54:00:E1:96:EB
    eth0_netmask=255.255.192.0
    eth0_gateway=10.104.0.1
    dns_nameserver="10.138.224.65 10.182.20.26 10.182.24.12"
    

    The parameter names above are for reference, and the values are used as examples only.

    The description of each parameter in the os.conf configuration file is as follows:

    Parameter Name Description
    hostname CVM name
    password Encrypted password
    eth0_ip_addr LAN IP of eth0
    eth0_mac_addr MAC address of eth0
    eth0_netmask Subnet mask of eth0
    eth0_gateway Gateway of eth0
    dns_nameserver DNS resolution server

    Limits

    • The image must meet the limits on Linux images as outlined in Import Images, except for cloudinit.
    • The system partition for importing the image is not full.
    • The imported image contains no vulnerability that can be exploited remotely.
    • We recommend you change the password immediately after the instance is created successfully with the forcibly imported image.

    Notes

    Note the following when configuring script parsing:

    • The script is executed automatically at startup. Please implement this requirement based on your operating system.
    • Mount /dev/cdrom and read os_action/os.conf file under the mount point to obtain the configuration information.
    • The password placed in CDROM by Tencent Cloud is encrypted. You can set new password with chpasswd -e.
    • Note that the encrypted password may contain special characters. We recommend you place it in a file and then set the password with chpasswd -e < passwd_file.*
    • When you use the forcibly imported image to create an instance and then create an image, you need to ensure that the script will still be executed to ensure that the instance is configured correctly. You can also install cloudinit in this instance.

    Directions

    Tencent Cloud provides a script sample based on CentOS. You can refer to it to create script for your images. During the creation, note that:

    • The script must be properly placed in the system before image import.
    • The script is not applicable to all operating systems. You need to modify it according to your own operating systems.
    1. Create an os_config script based on the following script sample.
      You can modify the script as needed.
      #!/bin/bash
      ### BEGIN INIT INFO
      # Provides:          os-config
      # Required-Start:    $local_fs $network $named $remote_fs
      # Required-Stop:
      # Should-Stop:
      # Default-Start:     2 3 4 5
      # Default-Stop:      0 1 6
      # Short-Description: config of os-init job
      # Description: run the config phase without cloud-init
      ### END INIT INFO
      ###################user settings#####################
      cdrom_path=`blkid -L config-2`
      load_os_config() {
       mount_path=$(mktemp -d /mnt/tmp.XXXX)
       mount /dev/cdrom $mount_path
       if [[ -f $mount_path/qcloud_action/os.conf ]]; then
           . $mount_path/qcloud_action/os.conf
           if [[ -n $password ]]; then
               passwd_file=$(mktemp /mnt/pass.XXXX)
               passwd_line=$(grep password $mount_path/qcloud_action/os.conf)
               echo root:${passwd_line#*=} > $passwd_file
           fi
           return 0
       else 
           return 1
       fi
      }
      cleanup() {
       umount /dev/cdrom
       if [[ -f $passwd_file ]]; then
           echo $passwd_file
           rm -f $passwd_file
       fi
       if [[ -d $mount_path ]]; then
           echo $mount_path
           rm -rf $mount_path
       fi
      }
      config_password() {
       if [[ -f $passwd_file ]]; then
           chpasswd -e < $passwd_file
       fi
      }
      config_hostname(){
       if [[ -n $hostname ]]; then
           sed -i "/^HOSTNAME=.*/d" /etc/sysconfig/network
           echo "HOSTNAME=$hostname" >> /etc/sysconfig/network
       fi
      }
      config_dns() {
       if [[ -n $dns_nameserver ]]; then
           dns_conf=/etc/resolv.conf
           sed -i '/^nameserver.*/d' $dns_conf
           for i in $dns_nameserver; do
               echo "nameserver $i" >> $dns_conf
           done
       fi
      }
      config_network() {
       /etc/init.d/network stop
       cat << EOF > /etc/sysconfig/network-scripts/ifcfg-eth0
      DEVICE=eth0
      IPADDR=$eth0_ip_addr
      NETMASK=$eth0_netmask
      HWADDR=$eth0_mac_addr
      ONBOOT=yes
      GATEWAY=$eth0_gateway
      BOOTPROTO=static
      EOF
       if [[ -n $hostname ]]; then
           sed -i "/^${eth0_ip_addr}.*/d" /etc/hosts
           echo "${eth0_ip_addr} $hostname" >> /etc/hosts
       fi
       /etc/init.d/network start
      }
      config_gateway() {
       sed -i "s/^GATEWAY=.*/GATEWAY=$eth0_gateway" /etc/sysconfig/network
      }
      ###################init#####################
      start() {
       if load_os_config ; then
           config_password
           config_hostname
           config_dns
           config_network
           cleanup
           exit 0
       else 
           echo "mount ${cdrom_path} failed"
           exit 1
       fi
      }
      RETVAL=0
      case "$1" in
       start)
           start
           RETVAL=$?
       ;;
       *)
           echo "Usage: $0 {start}"
           RETVAL=3
       ;;
      esac
      exit $RETVAL
    2. Place the os_config script in the /etc/init.d/ directory and execute the following command.
      chmod +x /etc/init.d/os_config
      chkconfig --add os_config
    3. Execute the following command to check whether os_config has been added to the startup service.
      chkconfig --list

      You must ensure that the script is correctly executed. If you fail to connect to the instance via SSH or network exception occurs after the image import, try to connect to the instance via the console to execute the script again. If such problems remain, contact the customer service.

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