Technology

如何使用 debootstrap 构建一个最小化的Ubuntu

一个简单的 debootstrap 部署教程。

debootstrap 是 Debian 及其附属分支下的一个工具，用来构建一套基本的系统(根文件系统)。生成的目录符合 Linux 文件系统标准(FHS)，即包含了 /boot、/etc、/bin、/usr 等等目录，但它比发行版本的 Linux 体积小很多

debootstrap 介绍

啥是 debootstrap

debootstrap 是 Debian 及其附属分支下的一个工具，用来构建一套基本的系统(根文件系统)。生成的目录符合 Linux 文件系统标准(FHS)，即包含了 /boot、/etc、/bin、/usr 等等目录，但它比发行版本的 Linux 体积小很多

似曾相识燕归来

debootstrap 有啥用

debootstrap 可以用来快速 简便的构建一个最小化的 debian 及其附属分支的最小化 rootfs

我们可以用其构建一个最小化的 rootfs (主要是这个相较于 Ubuntu Server 版本还是小得多)

如何使用 debootstrap

其实 使用 debootstrap 很简单 它已经被放入到默认源了 我们只需要 apt install 即可

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sudo apt install debootstrap

如何使用呢 自己看 详情 wiki

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sudo debootstrap [--arch 架构（可选项）][发行版本] [目录] [映像源（可选项）]

开始动手构建自己的 Ubuntu

我们这里使用 Ubuntu Server 20.04 作为 Live CD 来进行构建

进入 Shell 并安装 debootstrap

Ubuntu ISO shell

  1. 点击 Help

  2. Enter Shell

  3. （可选）修改 sources.list

  4. update sourcelist 并安装 debootstrap

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$ sudo apt update && apt install debootstrap
    Ign:1 cdrom://Ubuntu-Server 20.04 LTS _Focal Fossa_ - Release amd64 (20200423) focal InRelease
    Hit:2 cdrom://Ubuntu-Server 20.04 LTS _Focal Fossa_ - Release amd64 (20200423) focal Release
    Get:4 http://mirrors.aliyun.com/ubuntu focal InRelease [265 kB]
    Get:5 http://mirrors.aliyun.com/ubuntu focal-updates InRelease [107 kB]
    Get:6 http://mirrors.aliyun.com/ubuntu focal-backports InRelease [98.3 kB]
    Get:7 http://mirrors.aliyun.com/ubuntu focal-security InRelease [107 kB]
    Get:8 http://mirrors.aliyun.com/ubuntu focal/main amd64 Packages [970 kB]
    Get:9 http://mirrors.aliyun.com/ubuntu focal/main Translation-en [506 kB]
    Get:10 http://mirrors.aliyun.com/ubuntu focal/main amd64 c-n-f Metadata [29.5 kB]
    Get:11 http://mirrors.aliyun.com/ubuntu focal/restricted amd64 Packages [22.0 kB]
    Get:12 http://mirrors.aliyun.com/ubuntu focal/restricted Translation-en [6212 B]
    Get:13 http://mirrors.aliyun.com/ubuntu focal/restricted amd64 c-n-f Metadata [392 B]
    Get:14 http://mirrors.aliyun.com/ubuntu focal/universe amd64 Packages [8628 kB]
    Get:15 http://mirrors.aliyun.com/ubuntu focal/universe Translation-en [5124 kB]
    Get:16 http://mirrors.aliyun.com/ubuntu focal/universe amd64 c-n-f Metadata [265 kB]
    Get:17 http://mirrors.aliyun.com/ubuntu focal/multiverse amd64 Packages [144 kB]
    Get:18 http://mirrors.aliyun.com/ubuntu focal/multiverse Translation-en [104 kB]
    Get:19 http://mirrors.aliyun.com/ubuntu focal/multiverse amd64 c-n-f Metadata [9136 B]
    Get:20 http://mirrors.aliyun.com/ubuntu focal-updates/main amd64 Packages [197 kB]
    Get:21 http://mirrors.aliyun.com/ubuntu focal-updates/main Translation-en [77.7 kB]
    Get:22 http://mirrors.aliyun.com/ubuntu focal-updates/main amd64 c-n-f Metadata [5676 B]
    Get:23 http://mirrors.aliyun.com/ubuntu focal-updates/restricted amd64 Packages [11.0 kB]
    Get:24 http://mirrors.aliyun.com/ubuntu focal-updates/restricted Translation-en [3000 B]
    Get:25 http://mirrors.aliyun.com/ubuntu focal-updates/restricted amd64 c-n-f Metadata [116 B]
    Get:26 http://mirrors.aliyun.com/ubuntu focal-updates/universe amd64 Packages [110 kB]
    Get:27 http://mirrors.aliyun.com/ubuntu focal-updates/universe Translation-en [51.9 kB]
    Get:28 http://mirrors.aliyun.com/ubuntu focal-updates/universe amd64 c-n-f Metadata [4092 B]
    Get:29 http://mirrors.aliyun.com/ubuntu focal-updates/multiverse amd64 Packages [1172 B]
    Get:30 http://mirrors.aliyun.com/ubuntu focal-updates/multiverse Translation-en [540 B]
    Get:31 http://mirrors.aliyun.com/ubuntu focal-updates/multiverse amd64 c-n-f Metadata [116 B]
    Get:32 http://mirrors.aliyun.com/ubuntu focal-backports/main amd64 c-n-f Metadata [112 B]
    Get:33 http://mirrors.aliyun.com/ubuntu focal-backports/restricted amd64 c-n-f Metadata [116 B]
    Get:34 http://mirrors.aliyun.com/ubuntu focal-backports/universe amd64 Packages [2784 B]
    Get:35 http://mirrors.aliyun.com/ubuntu focal-backports/universe Translation-en [1272 B]
    Get:36 http://mirrors.aliyun.com/ubuntu focal-backports/universe amd64 c-n-f Metadata [192 B]
    Get:37 http://mirrors.aliyun.com/ubuntu focal-backports/multiverse amd64 c-n-f Metadata [116 B]
    Get:38 http://mirrors.aliyun.com/ubuntu focal-security/main amd64 Packages [106 kB]
    Get:46 http://mirrors.aliyun.com/ubuntu focal-security/universe amd64 c-n-f Metadata [1612 B]
    Get:47 http://mirrors.aliyun.com/ubuntu focal-security/multiverse amd64 Packages [1172 B]
    Get:48 http://mirrors.aliyun.com/ubuntu focal-security/multiverse Translation-en [540 B]
    Get:49 http://mirrors.aliyun.com/ubuntu focal-security/multiverse amd64 c-n-f Metadata [116 B]
    Fetched 17.1 MB in 6s (3096 kB/s)
    Reading package lists... Done
    Building dependency tree
    Reading state information... Done
    65 packages can be upgraded. Run 'apt list --upgradable' to see them.
    Reading package lists... Done
    Building dependency tree
    Reading state information... Done
    Suggested packages:
      arch-test squid-deb-proxy-client
    The following NEW packages will be installed:
      debootstrap
    0 upgraded, 1 newly installed, 0 to remove and 65 not upgraded.
    Need to get 39.4 kB of archives.
    After this operation, 299 kB of additional disk space will be used.
    Get:1 http://mirrors.aliyun.com/ubuntu focal-updates/main amd64 debootstrap all 1.0.118ubuntu1.1 [39.4 kB]
    Fetched 39.4 kB in 0s (221 kB/s)
    Selecting previously unselected package debootstrap.
    (Reading database ... 33860 files and directories currently installed.)
    Preparing to unpack .../debootstrap_1.0.118ubuntu1.1_all.deb ...
    Unpacking debootstrap (1.0.118ubuntu1.1) ...
    Setting up debootstrap (1.0.118ubuntu1.1) ...
    Processing triggers for man-db (2.9.1-1) ...
$ debootstrap
    I: usage: [OPTION]... <suite> <target> [<mirror> [<script>]]
    I: Try `debootstrap --help' for more information.
    E: You must specify a suite and a target.

给硬盘分区

这步没啥好说的 用 cfdisk 进行分区 使用 mkfs.ext4 来格式化硬盘（请记住如何分区的！！！！（后面编写 fstab 会涉及到））

/dev 路径挂载位置分区模式作用
/dev/sda1/bootfat32负责 efi 引导
/dev/sda2swapswap内存交换
/dev/sda3/ext4根目录
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$ mkfs.ext4 /dev/sda3
mke2fs 1.45.5 (07-Jan-2020)
Creating filesystem with 9311995 4k blocks and 2330160 inodes
Filesystem UUID: fbe7f7fe-1997-4ab3-929f-52aa73aa72eb
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000, 7962624

Allocating group tables: done
Writing inode tables: done
Creating journal (65536 blocks): done
Writing superblocks and filesystem accounting information: done

$ mkswap /dev/sda2
Setting up swapspace version 1, size = 4 GiB (4294963200 bytes)s
no label, UUID=9fe83e8e-cd78-4a25-8a1e-ab305181c46d
$ swapon /dev/sda2
$ mkfs.vfat /dev/sda1
mkfs.fat 4.1 (2017-01-24)

挂载分区并释放 rootfs

这里构建选择最新的 Focal X86_64 位

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$ mkdir /target
$ mount /dev/sda3 /target
$ debootstrap focal /target http://mirrors.aliyun.com/ubuntu
I: Retrieving InRelease
I: Checking Release signature
I: Valid Release signature (key id F6ECB3762474EDA9D21B7022871920D1991BC93C)
I: Retrieving Packages
I: Validating Packages
I: Resolving dependencies of required packages...
I: Resolving dependencies of base packages...
I: Checking component main on http://mirrors.aliyun.com/ubuntu...
I: Retrieving adduser 3.118ubuntu2
I: Validating adduser 3.118ubuntu2
I: Retrieving apt 2.0.2
I: Validating apt 2.0.2
…………………………………………………………
I: Configuring console-setup...
I: Configuring kbd...
I: Configuring ubuntu-minimal...
I: Configuring libc-bin...
I: Configuring systemd...
I: Configuring ca-certificates...
I: Base system installed successfully. ##当你看到这句时 说明你的操作没有问题

chroot 并进行基本设置

修改软件源

默认 rootfs 中的软件源不完整 我们这里 cp 一下 live cd 的软件源

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cp /etc/apt/sources.list /target/etc/apt/sources.list;sed -i 3d /target/etc/apt/sources.list

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$ cat >> /target/etc/apt/sources.list << EOF
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://mirrors.aliyun.com/ubuntu/ focal main restricted
# deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted
# deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://mirrors.aliyun.com/ubuntu/ focal universe
# deb-src http://mirrors.aliyun.com/ubuntu/ focal universe
deb http://mirrors.aliyun.com/ubuntu/ focal-updates universe
# deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://mirrors.aliyun.com/ubuntu/ focal multiverse
# deb-src http://mirrors.aliyun.com/ubuntu/ focal multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-updates multiverse
# deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
# deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu focal partner
# deb-src http://archive.canonical.com/ubuntu focal partner
deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted
# deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted
deb http://mirrors.aliyun.com/ubuntu/ focal-security universe
# deb-src http://mirrors.aliyun.com/ubuntu/ focal-security universe
deb http://mirrors.aliyun.com/ubuntu/ focal-security multiverse
# deb-src http://mirrors.aliyun.com/ubuntu/ focal-security multiverse

编写 fstab

这里推荐一下这篇文章 linux 之 fstab 文件详解 来自 csdn richerg85

fstab 主要由这几部分组成

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<file system>   <dir>   <type>  <options>   <dump>  <pass>
（/dev下的位置）（挂载位置）（文件系统）（挂载参数）（dump 工具通过它决定何时作备份）（fsck 读取 <pass> 的数值来决定需要检查的文件系统的检查顺序。）

这里以我的 fstab 文件作为实例

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$ cat >> /target/etc/fstab << EOF
tmpfs           /tmp    tmpfs   nodev,nosuid            0       0
/dev/sda2       none    swap    defaults                0       0
/dev/sda3       /       ext4    defaults,noatime        0       0

chroot 进入系统

先挂载 efi 分区

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mkdir /target/boot/efi && \
mount /dev/sda1 /target/boot/efi

挂载 proc 等分区

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for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /target$i; done

挂载并安装 grub 和 kernel(这里安装的是虚拟化内核)

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$ sudo chroot /target
$ sudo passwd ##配置passwd
New password:
Retype new password:
passwd: password updated successfully
$ sudo apt install grub-efi-amd64 linux-virtual -y ##安装grub和kernel
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  efibootmgr gettext-base grub-common grub-efi-amd64-bin grub-efi-amd64-signed grub2-common libefiboot1 libefivar1
  libfreetype6 libfuse2 libpng16-16 linux-headers-generic linux-headers-virtual os-prober sbsigntool secureboot-db
Suggested packages:
rvice.
Running in chroot, ignoring request: daemon-reload
Running in chroot, ignoring request: is-active
Running in chroot, ignoring request: start
Setting up libefiboot1:amd64 (37-2ubuntu2) ...
Setting up linux-virtual (5.4.0.26.32) ...
Setting up libfreetype6:amd64 (2.10.1-2) ...
Setting up efibootmgr (17-1) ...
Setting up grub-common (2.04-1ubuntu26) ...
Running in chroot, ignoring request: daemon-reload
Running in chroot, ignoring request: daemon-reload
Running in chroot, ignoring request: is-active
Running in chroot, ignoring request: restart
update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
Running in chroot, ignoring request: daemon-reload
Running in chroot, ignoring request.
Running in chroot, ignoring request: daemon-reload
Running in chroot, ignoring request: is-active
Running in chroot, ignoring request: restart
Setting up os-prober (1.74ubuntu2) ...
Setting up grub-efi-amd64-bin (2.04-1ubuntu26) ...
Setting up grub2-common (2.04-1ubuntu26) ...
Setting up grub-efi-amd64 (2.04-1ubuntu26) ...
Setting up grub-efi-amd64-signed (1.142+2.04-1ubuntu26) ...
Processing triggers for systemd (245.4-4ubuntu3) ...
Running in chroot, ignoring request: daemon-reload
Processing triggers for libc-bin (2.31-0ubuntu9) ...

安装 grub2

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$ grub-install /dev/sda
update-grub Installing for x86_64-efi platform.
Installation finished. No error reported.
$ update-grub
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.4.0-26-generic
Found initrd image: /boot/initrd.img-5.4.0-26-generic
Adding boot menu entry for UEFI Firmware Settings
done

设置网络

Ubuntu 18.04 及其上的 Server 版本默认使用 systemd-networkd 联网

先使用 ip a 获取设备

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$ ip a
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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 ## ens33就是网络设备
    link/ether 00:0c:29:9d:a0:73 brd ff:ff:ff:ff:ff:ff
    inet 192.168.57.140/24 brd 192.168.57.255 scope global dynamic ens33
       valid_lft 5433596sec preferred_lft 5433596sec
    inet6 fe80::20c:29ff:fe9d:a073/64 scope link
       valid_lft forever preferred_lft forever

配置所有网卡 DHCP 联网

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$ cat >> /etc/systemd/network/ens33.network << EOF
[Match]
Name=*
[Network]
DHCP=both

重启

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$ exit
exit

reboot

PS: 第一次开机会有一点点慢（就亿点点）

重启并配置网络

启动 systemd-networkd

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$ systemctl enable --now systemd-networkd
Created symlink /etc/systemd/system/dbus-org.freedesktop.network1.service → /lib/systemd/system/systemd-networkd.service.
Created symlink /etc/systemd/system/multi-user.target.wants/systemd-networkd.service → /lib/systemd/system/systemd-networkd.service.
Created symlink /etc/systemd/system/sockets.target.wants/systemd-networkd.socket → /lib/systemd/system/systemd-networkd.socket.
Created symlink /etc/systemd/system/network-online.target.wants/systemd-networkd-wait-online.service → /lib/systemd/system/systemd-networkd-wait-online.service.

修改 hostname 并添加 hosts

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$ hostnamectl set-hostname vm-ubuntu-test
$ cat >> /etc/hosts << EOF
127.0.0.1       vm-ubuntu-test localhost
::1             vm-ubuntu-test localhost ip6-localhost ip6-loopback
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters

最后 reboot 生效

享受全新的 ubuntu 体验吧