制作清爽干净的kvm基础镜像

    在平时使用时，为了减少存储空间和加快网络传输速度，我们总希望能把基础镜像做的尽量小，本文介绍如何制作清爽干净的kvm基础镜像。

1. 根据自身需求，对系统进行配置：

   • 这一步是为了确保系统符合你的需求，比如安装必要的软件，配置网络等。

2. 卸载不需要的软件：

   • 使用 yum remove 或 dnf remove 命令卸载不需要的软件包。例如：
     bash<button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary copyBtn___l3xJQ css-xox1ca" tabindex="0" type="button"></button>

     yum remove [package_name]
   • 确保不要卸载系统运行所必需的软件。

3. 对系统缓存进行清理：

   • 清理临时文件和日志可以减少镜像大小。以下命令可以清理缓存：
     bash<button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary copyBtn___l3xJQ css-xox1ca" tabindex="0" type="button"></button>

     rm -rf /tmp/* rm -f /etc/udev/rules.d/70-persistent-net.rules rm -f /var/log/wtmp /var/log/btmp /var/log/anaconda/* cd /var/log for i in cron dmesg dmesg.old lastlog maillog messages pm-powersave.log secure Xorg.0.log Xorg.0.log.old Xorg.9.log Xorg.9.log.old do true > $i done dmesg -c echo >/root/.bash_history yum clean all cloud-init clean rm -rf /var/lib/cloud history -c

4. 使用 dd 命令将客户机未使用的磁盘空间用0填满：

   • 这一步确保未使用的磁盘空间被标记为0，从而在转换为 qcow2 镜像时不会被错误地认为是已使用空间。例如：
     bash<button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary copyBtn___l3xJQ css-xox1ca" tabindex="0" type="button"></button>

     dd if=/dev/zero of=~/junk rm -f ~/junk

5. 关机：

   • 使用 halt -p 命令安全地关闭系统：
     bash<button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary copyBtn___l3xJQ css-xox1ca" tabindex="0" type="button"></button>

     halt -p

6. 在宿主机上，执行镜像整理：

   • 使用 virt-sysprep 命令清理镜像中的临时文件和日志，确保镜像是干净的。如果没有安装 libguestfs-tools，可以通过以下命令安装：
     bash<button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary copyBtn___l3xJQ css-xox1ca" tabindex="0" type="button"></button>

     yum install libguestfs-tools -y
   • 然后执行：
     bash<button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary copyBtn___l3xJQ css-xox1ca" tabindex="0" type="button"></button>

     virt-sysprep -a kvm-base.qcow2

7. 压缩并制作新镜像：

   • 使用 qemu-img convert 命令将镜像转换为压缩的 qcow2 格式：
     bash<button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary copyBtn___l3xJQ css-xox1ca" tabindex="0" type="button"></button>

     qemu-img convert -p -c -O qcow2 kvm-base.qcow2 new.qcow2

8. 检查镜像是否有错误：

   • 使用 qemu-img check 命令检查新镜像的完整性：
     bash<button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeSmall MuiButton-textSizeSmall MuiButton-colorPrimary copyBtn___l3xJQ css-xox1ca" tabindex="0" type="button"></button>

     qemu-img check new.qcow2