Ubuntu20.04 Focal Cloud Image扩容以及KVM安装的问题记录
这篇内容可能有些不符合正常用法, 正常的Cloud Image用法参考 https://www.cnblogs.com/milton/p/16789185.html
运行Ubuntu20.04的KVM虚机遇到一些问题, 单独总结一下
KVM QCOW2 镜像扩容
不能用virt-resize --expand /dev/sda1 old.qcow2 new.qcow2这样的命令, 这样制作出来的镜像, 丢失了/dev/sda14, /dev/sda15这两个分区, 变成了 /dev/sda1, /dev/sda2, /dev/sda3, 会导致install --import时卡住. 用virt-filesystems --long --parts --blkdevs -h -a new.qcow2命令查看, 会发现/dev/sda1的大小变成了4MB
因为镜像是为云服务提供的, 安装启动时配合init脚本扩容, 如果要脱机扩容的话, 网上几乎查不到能解决这个问题的办法, 最后是通过 转换为raw格式->parted调整分区大小->转回qcow2完成的, 参考 https://blog.richliu.com/2018/08/25/2318/change-ubuntu-cloud-image-size/
转换步骤
resize原始镜像
qemu-img resize focal-server-cloudimg-amd64-50g.qcow2 50G
转换为raw格式镜像
qemu-img convert -f qcow2 -O raw focal-server-cloudimg-amd64-50g.qcow2 focal-server-cloudimg-amd64.raw
调整raw分区大小
# 重命名以防混淆
mv focal-server-cloudimg-amd64.raw focal-server-cloudimg-amd64-50g.raw
# 运行parted
parted focal-server-cloudimg-amd64-50g.raw
######################## 开始
GNU Parted 3.1
Using /data/backup/vm_images/focal-server-cloudimg-amd64-50g.raw
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Error: The backup GPT table is not at the end of the disk, as it should be.
This might mean that another operating system believes the disk is smaller.
Fix, by moving the backup to the end (and removing the old backup)?
Fix/Ignore/Cancel? Fix
Warning: Not all of the space available to
/data/backup/vm_images/focal-server-cloudimg-amd64-50g.raw appears to be used,
you can fix the GPT to use all of the space (an extra 100245504 blocks) or
continue with the current setting?
Fix/Ignore? Fix
Model: (file)
Disk /data/backup/vm_images/focal-server-cloudimg-amd64-50g.raw: 53.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
14 1049kB 5243kB 4194kB bios_grub
15 5243kB 116MB 111MB fat32 boot
1 116MB 2361MB 2245MB ext4
(parted) resizepart
Partition number? 1
End? [2361MB]? 53.7G
(parted) p
Model: (file)
Disk /data/backup/vm_images/focal-server-cloudimg-amd64-50g.raw: 53.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
14 1049kB 5243kB 4194kB bios_grub
15 5243kB 116MB 111MB fat32 boot
1 116MB 53.7GB 53.6GB ext4
(parted) q
########################### 结束
检查raw格式的分区大小是否正确
virt-filesystems --long --parts --blkdevs -h -a focal-server-cloudimg-amd64-50g.raw
Name Type MBR Size Parent
/dev/sda1 partition - 50G /dev/sda
/dev/sda14 partition - 4.0M /dev/sda
/dev/sda15 partition - 106M /dev/sda
/dev/sda device - 50G -
转回qcow2格式
qemu-img convert -f raw -O qcow2 focal-server-cloudimg-amd64-50g.raw focal-server-cloudimg-amd64-50g-resized.qcow2
# 如果需要压缩, 带上`-c`参数, 结果文件大小可能会缩小一半以上
qemu-img convert -c -f raw -O qcow2 ubuntu-20.04-minimal-cloudimg-amd64.raw ubuntu-20.04-minimal-cloudimg-amd64-50g-compressed.qcow2
大小对比, 最后一个是原镜像, 第一第二个分别是压缩和没压缩的结果
-rw-r--r-- 1 milton milton 264110080 Oct 8 14:20 ubuntu-20.04-minimal-cloudimg-amd64-50g-compressed.qcow2
-rw-r--r-- 1 milton milton 859832320 Oct 8 14:16 ubuntu-20.04-minimal-cloudimg-amd64-50g.qcow2
-rw-rw-r-- 1 milton milton 264045344 Oct 8 14:05 ubuntu-20.04-minimal-cloudimg-amd64.img
再次检查
virt-filesystems --long --parts --blkdevs -h -a focal-server-cloudimg-amd64-50g-resized.qcow2
Name Type MBR Size Parent
/dev/sda1 partition - 50G /dev/sda
/dev/sda14 partition - 4.0M /dev/sda
/dev/sda15 partition - 106M /dev/sda
/dev/sda device - 50G -
经过上面的操作, 这个镜像在安装后只需要执行resize2fs /dev/vda1就能扩充分区了.
root口令
focal-server-cloudimg-xxx 这些镜像是为云环境创建的, 会配合一个init脚本(或者iso)启动并创建普通用户, 默认root不能登录也没有密码, 而单机运行还是需要root的, 所以在安装前, 要设置一下root口令:
virt-customize -a some.qcow2c --root-password password:[your password]
import安装虚机
命令
virt-install --name vm_ub01 --vcpus 4 --memory 8192 --disk /data/vms/vm_ubtu.qcow2 --graphics none --import --os-type linux --os-variant ubuntu20.04 --network bridge=br0,model=virtio
网络配置
这些是在虚机上执行的, 在install --import之后, 虚机网卡是未启动的, 而且net-tools也没安装, 只能通过基础的ip命令进行操作
# 查看ip, 可以看到有一个未启动的ens3网口
ip addr
# 启动nes3,
ip link set ens3 up
# 再次查看, 并无ipv4地址
ip addr
# 查看网卡硬件信息, 这里可以看到mac地址和网口名称
lshw -class network
# 增加网络配置
vi /etc/netplan/99_config.yaml
# 内容开始
network:
version: 2
renderer: networkd
ethernets:
ens3:
dhcp4: true
# 内容结束, 用下面的命令启用
netplan apply
# 再次查看, 这时候就有ip了
ip addr
# ping检查连通性
ping 202.38.64.1
启动sshd失败
虚机上启动ssh, 出现ssh.service: Start request repeated too quick的错误
用sshd -t检查, 提示no hostkey
sshd: no hostkeys available -- exiting.
重新生成hostkey
ssh-keygen -A
ssh-keygen: generating new host keys: RSA DSA ECDSA ED25519
之后重启sshd就正常了
关于hostkey
hostkey就是ssh服务中, 服务端的私钥, 正常情况是随着OpenSSH安装时一起生成的.
In OpenSSH, host keys are usually stored in the /etc/ssh directory, in files starting with ssh_host_<rsa/dsa/ecdsa/ed25519>_key (the location can be changed in server configuration files).
Host keys are normally generated automatically when OpenSSH is first installed or when the computer is first booted. The ssh-keygen program can be used for generating additional host keys or for replacing existing keys.
root不能通过密码登录ssh
需要修改/etc/ssh/sshd_config, 将这两行改成下面的值, 然后重启ssh服务
PermitRootLogin yes
PasswordAuthentication yes
参考
- SSH Host Key - What, Why, How https://www.ssh.com/academy/ssh/host-key
- 如何正确使用cloud-image创建虚机 https://powersj.io/posts/ubuntu-qemu-cli/
