如何快速启动KVM虚拟机并用自定义用户登录

以ubuntu 虚拟机为例，很多时候创建了KVM虚拟机之后，想ssh登录进去做一些操作，但是却不知道用户名和密码，最早的时候ubuntu 的cloud image 内置了一个cirros的用户名，密码也是cirros，现在好像没有这个用户了，所以想ssh 虚拟机的话，可以借助cloudinit 来在启动时创建一个指定的用户。

以下以ubuntu22.04为例说明一下操作步骤
1 下载对应os 架构image

wget https://cloud-images.ubuntu.com/releases/22.04/release-20240319/ubuntu-22.04-server-cloudimg-amd64.img  

 
2 创建cloud-init.cfg 配置文件，设置一个默认用户ubuntu设置密码为password

root@test# cat cloud-init.cfg
#cloud-config
system_info:
  default_user:
    name: ubuntu /
    home: /home/ubuntu

password: password
chpasswd: { expire: False }
hostname: ubuntu

# configure sshd to allow users logging in using password
# rather than just keys
ssh_pwauth: True

3 生成cloud-init disk

cloud-localds cloud-init.iso cloud-init.cfg

4 启动虚拟机

root@test:# virt-install --connect qemu:///system  --name test-vm  --memory 2048 --vcpus 2 --disk ubuntu-22.04-server-cloudimg-amd64.img --import --os-variant ubuntu22.04 --noautoconsole  --network network=default,model=virtio     --graphics none     --console pty,target_type=serial --disk data/ubuntu/cloud-init.iso,device=cdrom

root@test# virsh list
 Id   Name          State
-----------------------------
 24   test-vm       running

root@s11:~/nf# virsh console 24
Connected to domain 'test-vm'
Escape character is ^] (Ctrl + ])

Ubuntu 22.04.4 LTS ubuntu ttysclp0

ubuntu login: ubuntu
Password: <>

5 登录进虚拟机后，找到vm的IP

ubuntu@ubuntu:~$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enc1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:37:f5:86 brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.178/24 metric 100 brd 192.168.122.255 scope global dynamic enc1
       valid_lft 3562sec preferred_lft 3562sec
    inet6 fe80::5054:ff:fe37:f586/64 scope link
       valid_lft forever preferred_lft forever

6.用ssh 登录虚拟机

root@test# ssh [email protected]
The authenticity of host '192.168.122.178 (192.168.122.178)' can't be established.
ED25519 key fingerprint is SHA256:un8GId28KD2GbMoxQkE2jJJEQRPFXbSlBZ69LEkd57o.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '192.168.122.178' (ED25519) to the list of known hosts.
[email protected]'s password:
Welcome to Ubuntu 22.04.4 LTS (GNU/Linux 5.15.0-101-generic s390x)
ubuntu@ubuntu:~$

Tips： 退出console时，用Ctrl+C或exit都退不出来，要用Ctrl+] （右中括号） 就可以了  

参考：https://www.cnblogs.com/even160941/p/17605840.html