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[#]: subject: "Building RHEL and RHEL UBI images with mkosi"
[#]: via: "https://fedoramagazine.org/create-images-directly-from-rhel-and-rhel-ubi-package-using-mkosi/"
[#]: author: "Zbigniew Jędrzejewski-Szmek https://fedoramagazine.org/author/zbyszek/"
[#]: collector: "lujun9972/lctt-scripts-1700446145"
[#]: translator: "GlassFoxowo"
[#]: reviewer: " "
[#]: publisher: " "
[#]: url: " "
Building RHEL and RHEL UBI images with mkosi
======
![][1]
Photo by [Saad Salim][2] on [Unsplash][3]
Mkosi is a lightweight tool to build images from distribution packages. This article describes how to use mkosi to build images with packages from RHEL (Red Hat Enterprise Linux) and RHEL UBI. RHEL Universal Base Image is a subset of RHEL that is freely available without a subscription.
### Mkosi features
Mkosi supports a few output formats, but the most important one is [Discoverable Disk Images][4] (DDIs). The same DDI can be used to boot a container, as a virtual machine, copied to a USB stick and used to boot a real machine, and finally copied from the USB stick to the disk to boot from it. The image has a standarized layout and metadata that describes its purpose.
Mkosi relies on other tools to do most of the work: _systemd-repart_ to create partitions on a disk image, _mkfs.btrfs_ / _mkfs.ext4_ / _mkfs.xfs_ /… to write the file systems, and _dnf_ / _apt_ / _pacman_ / _zypper_ to download and unpack packages.
Mkosi supports a range of distributions: Debian and Ubuntu, Arch Linux, OpenSUSE, and of course Fedora, CentOS Stream and derivatives, and now RHEL UBI and RHEL since the last release. Because the actual “heavy lifting” is done by other tools, mkosi can do cross builds. This is where one distro is used to build images for various other distros. The only requirement is that the appropriate tools are installed on the host. Fedora has native packages for _apt_ , _pacman_ , and _zypper_ , so it provides a good base to use mkosi to build any other distribution.
There are some nifty features: images can be created by an unprivileged user, or in a container without device files, in particular access to loopback devices. It can also launch those images as VMs (using _qemu_ ) without privileges.
The configuration is declarative and very easy to create. _systemd-repart_ is used to create disk partitions, and _repart.d_ configuration files are used to define how this should be done.
For more details see two talks by Daan DeMeyer at the All Systems Go conference: [systemd-repart: Building Discoverable Disk Images][5] and [mkosi: Building Bespoke Operating System Images][6].
### Project goal
One goal for Mkosi is to allow the testing of a software project against various distributions. It will create an image for a distribution (using packages from that distribution) and then compile and install the software project into that image, inserting additional files that are not part of a package. But the first stage, the creation of an image from packages, is useful on its own. This is what we will show first.
We[1][7] recently added support for RHEL and RHEL UBI. Let’s start with RHEL UBI, just building an image out of distro packages.
Please note that the examples below require mkosi 19, and will not work with earlier versions.
### A basic RHEL UBI image with a shell
```
$ mkdir -p mkosi.cache
$ mkosi \
-d rhel-ubi \
-t directory \
-p bash,coreutils,util-linux,systemd,rpm \
--autologin
```
The commands above specify the distribution ‘rhel-ubi’, the output format ‘directory’, and request that packages _bash_ , _coreutils_ , …, _rpm_ be installed. _rpm_ isn’t normally needed _inside_ of the image, but here it will be useful for introspection. We also enable automatic login as the root user.
Before the build is started, we create the cache directory _mkosi.cache_. When a cache directory is present Mkosi uses it automatically to persist downloaded rpms. This will make subsequent invocations on the same package set much faster.
We can then boot this image as a container using _systemd-nspawn_ :
```
$ sudo mkosi \
-d rhel-ubi \
-t directory \
boot
```
```
systemd 252-14.el9_2.3 running in system mode (+PAM +AUDIT +SELINUX -APPARMOR +IMA +SMACK +SECCOMP +GCRYPT +GNUTLS +OPENSSL +ACL +BLKID +CURL +ELFUTILS -FIDO2 +IDN2 -IDN -IPTC +KMOD +LIBCRYPTSETUP +LIBFDISK +PCRE2 -PWQUALITY +P11KIT -QRENCODE +TPM2 +BZIP2 +LZ4 +XZ +ZLIB +ZSTD -BPF_FRAMEWORK +XKBCOMMON +UTMP +SYSVINIT default-hierarchy=unified)
Detected virtualization systemd-nspawn.
Detected architecture x86-64.
Detected first boot.
Red Hat Enterprise Linux 9.2 (Plow)
...
[ OK ] Created slice Slice /system/getty.
[ OK ] Created slice Slice /system/modprobe.
[ OK ] Created slice User and Session Slice.
...
[ OK ] Started User Login Management.
[ OK ] Reached target Multi-User System.
Red Hat Enterprise Linux 9.2 (Plow)
Kernel 6.5.6-300.fc39.x86_64 on an x86_64
image login: root (automatic login)
[root@image ~]# rpm -q rpm systemd
rpm-4.16.1.3-22.el9.x86_64
systemd-252-14.el9_2.3.x86_64
```
As mentioned earlier, the image can be used to boot a VM. In this setup, it is not possible — our image doesn’t have a kernel. In fact, RHEL UBI doesn’t provide a kernel at all, so we can’t use it to boot (in a VM or on bare metal).
### Creating an image
I also promised an image, but so far we only have a directory. Let’s actually create an image:
```
$ mkosi \
-d rhel-ubi \
-t disk \
-p bash,coreutils,util-linux,systemd,rpm \
--autologin
```
This produces _image.raw_ , an disk image with a GPT partition table, and a single root partition (for the native architecture).
```
$ sudo systemd-dissect image.raw
Name: image.raw
Size: 301.0M
Sec. Size: 512
Arch.: x86-64
Image UUID: dcbd6499-409e-4b62-b251-e0dd15e446d5
OS Release: NAME=Red Hat Enterprise Linux
VERSION=9.2 (Plow)
ID=rhel
ID_LIKE=fedora
VERSION_ID=9.2
PLATFORM_ID=platform:el9
PRETTY_NAME=Red Hat Enterprise Linux 9.2 (Plow)
ANSI_COLOR=0;31
LOGO=fedora-logo-icon
CPE_NAME=cpe:/o:redhat:enterprise_linux:9::baseos
HOME_URL=https://www.redhat.com/
DOCUMENTATION_URL=https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9
BUG_REPORT_URL=https://bugzilla.redhat.com/
REDHAT_BUGZILLA_PRODUCT=Red Hat Enterprise Linux 9
REDHAT_BUGZILLA_PRODUCT_VERSION=9.2
REDHAT_SUPPORT_PRODUCT=Red Hat Enterprise Linux
REDHAT_SUPPORT_PRODUCT_VERSION=9.2
Use As: ✗ bootable system for UEFI
✓ bootable system for container
✗ portable service
✗ initrd
✗ sysext extension for system
✗ sysext extension for initrd
✗ sysext extension for portable service
RW DESIGNATOR PARTITION UUID PARTITION LABEL FSTYPE ARCHITECTURE VERITY GROWFS NODE PARTNO
rw root 1236e211-4729-4561-a6fc-9ef8f18b828f root-x86-64 xfs x86-64 no yes /dev/loop0p1 1
```
OK, we have an image, the image has some content from RHEL UBI packages. How do we add our own stuff on top?
### Extending an image with your own files
There are a few ways to extend the image, including compiling something from scratch. But first let’s do something easier and inject a provided file system into the image:
```
$ mkdir -p mkosi.extra/srv/www/content
$ cat >mkosi.extra/srv/www/content/index.html <<'EOF'
<h1>Hello, World!</h1>
EOF
```
The image will now have _/srv/www/content/index.html_.
This method is used to inject additional configuration or simple programs.
### Building from source
Now let’s do the full monty and build something from sources. For example, a trivial meson project with a single C file:
```
$ cat >hello.c <<'EOF'
#include <stdio.h>
int main(int argc, char **argv) {
char buf[1024];
FILE *f = fopen("/srv/www/content/index.html", "re");
size_t n = fread(buf, 1, sizeof buf, f);
fwrite(buf, 1, n, stdout);
fclose(f);
return 0;
}
EOF
$ cat >meson.build <<'EOF'
project('hello', 'c')
executable('hello', 'hello.c',
install: true)
EOF
```
```
$ cat >mkosi.build <<'EOF'
set -ex
mkosi-as-caller rm -rf "$BUILDDIR/build"
mkosi-as-caller meson setup "$BUILDDIR/build" "$SRCDIR"
mkosi-as-caller meson compile -C "$BUILDDIR/build"
meson install -C "$BUILDDIR/build" --no-rebuild
EOF
$ chmod +x mkosi.build
```
To summarize: we have some source code ( _hello.c_ ), a build system configuration ( _meson.build_ ), and a glue script ( _mkosi.build_ ) that is to be invoked by _mkosi_. For a “real” project, we would have the same elements, just more complex.
The script requires some explanation. Mkosi uses user namespaces when creating the image. This allows the package managers (e.g. _dnf_ ) to install files owned by different users even though it is invoked by a normal unprivileged user. We are using _mkosi-as-caller_ to switch back to the calling user to do the compilation. This way, the files created during compilation under $BUILDDIR will be owned by the calling user.
Now let’s build the image with our program. Compared to the previous invocation, we need additional packages: _meson_ , _gcc_. Since we now have a build script, mkosi will execute two build stages: first an build image is built, and the build script is invoked in it, and the installation artifacts are stashed in a temporary directory, then a final image is built, and the installation artifacts are injected. (Mkosi sets $DESTDIR, and _meson install_ uses $DESTDIR automatically, so the right things happen without us having to specify things explicitly.)
```
$ mkosi \
-d rhel-ubi \
-t disk \
-p bash,coreutils,util-linux,systemd,rpm \
--autologin \
--build-package=meson,gcc \
--build-dir=mkosi.builddir \
--build-script=mkosi.build \
-f
```
At this point we have the image _image.raw_ with a custom payload. We can start our freshly minted executable as a shell command:
```
$ sudo mkosi -d rhel-ubi -t directory shell hello
<h1>Hello, World!</h1>
```
### Obtaining a developer subscription for RHEL
RHEL UBI is intended for use primarily as a base layer for container builds. It has a limited set of packages available (about 1500). Let’s now switch to a full RHEL installation.
The easiest way to get access to RHEL is with a [developer license][8]. It provides an entitlement to register 16 physical or virtual nodes running RHEL, with self-service support.
First, [create an account][9]. After that, head over to [management][10] and make sure “Simple content access for Red Hat Subscription Management” is enabled. Then, [create a new activation key][11] with “Red Hat Developer Subscription for Individuals” selected. Make note of the Organization ID that is shown. We’ll refer to the key name and organization ID as $KEY_NAME and $ORGANIZATION_ID below.
Now we are ready to consume RHEL content:
```
$ sudo dnf install subscription-manager
$ sudo subscription-manager register \
--org $ORGANIZATION_ID --activationkey $KEY_NAME
```
### Building an image using RHEL
In previous examples, we specified all configuration through parameter switches. This is nice for quick development, but can become unwieldy. RHEL is a serious distribution, so let’s use a configuration file instead:
```
$ cat >mkosi.conf <<'EOF'
[Output]
Format=directory
Output=rhel-directory
[Distribution]
Distribution=rhel
[Content]
Packages=
bash
coreutils
util-linux
systemd
systemd-boot
systemd-udev
kernel-core
Bootable=yes
Bootloader=uki
Autologin=yes
WithDocs=no
EOF
```
Let’s first check if everything is kosher:
```
$ mkosi summary
```
And now let’s build the image (err, directory):
```
$ mkosi build
$ mkosi qemu
```
```
Welcome to Red Hat Enterprise Linux 9.2 (Plow)!
[ OK ] Created slice Slice /system/modprobe.
[ OK ] Reached target Initrd Root Device.
[ OK ] Reached target Initrd /usr File System.
[ OK ] Reached target Local Integrity Protected Volumes.
[ OK ] Reached target Local File Systems.
[ OK ] Reached target Path Units.
[ OK ] Reached target Remote Encrypted Volumes.
[ OK ] Reached target Remote Verity Protected Volumes.
[ OK ] Reached target Slice Units.
[ OK ] Reached target Swaps.
...
[ OK ] Listening on Journal Socket.
[ OK ] Listening on udev Control Socket.
[ OK ] Listening on udev Kernel Socket.
...
Red Hat Enterprise Linux 9.2 (Plow)
Kernel 5.14.0-284.30.1.el9_2.x86_64 on an x86_64
localhost login: root (automatic login)
[root@localhost ~]#
```
Yes, we built the “image” as a directory with a file system tree, and booted it as a virtual machine.
In the booted virtual machine, _findmnt /_ shows that the root file systems is virtiofs. This is a virtual file system that exposes a directory from the host to the guest. We _could_ build a more traditional image with a partition table and file systems inside of a file, but a directory+virtiofs is quick and nicer for development.
The image that we just booted is not registered. To allow updates to be downloaded from _inside_ of the image, we would have to add _yum_ , _subscription-manager_ , and _NetworkManager_ to the package list, and before we download any updates, call _subscription-manager_ in the same way as above. Once we do that, we have about 4500 packages at our disposal in the basic repositories, and a few dozen additional repositories with more specialized packages.
### Finally
And that’s all I have for today. If you have questions, find us on Matrix at [#mkosi:matrix.org][12] or on the [systemd mailing list][13].
1. Daan DeMeyer, Lukáš Nykrýn, Michal Sekletár, Zbigiew Jędrzejewski-Szmek [↩︎][14]
--------------------------------------------------------------------------------
via: https://fedoramagazine.org/create-images-directly-from-rhel-and-rhel-ubi-package-using-mkosi/
作者：[Zbigniew Jędrzejewski-Szmek][a]
选题：[lujun9972][b]
译者：[译者ID](https://github.com/译者ID)
校对：[校对者ID](https://github.com/校对者ID)
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
[a]: https://fedoramagazine.org/author/zbyszek/
[b]: https://github.com/lujun9972
[1]: https://fedoramagazine.org/wp-content/uploads/2023/10/building_w_mkosi-816x345.jpg
[2]: https://unsplash.com/@saadx?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash
[3]: https://unsplash.com/photos/aerial-photo-of-people-in-park-at-daytime-PqRvLsjD_TU?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash
[4]: https://uapi-group.org/specifications/specs/discoverable_disk_image/
[5]: https://media.ccc.de/v/all-systems-go-2023-191-systemd-repart-building-discoverable-disk-images
[6]: https://media.ccc.de/v/all-systems-go-2023-190-mkosi-building-bespoke-operating-system-images
[7]: tmp.1bzWuYb2vw#a08aaa7d-ee14-4565-80a0-e3d19b21ad26
[8]: https://developers.redhat.com/articles/faqs-no-cost-red-hat-enterprise-linux
[9]: https://developers.redhat.com/register
[10]: https://access.redhat.com/management
[11]: https://access.redhat.com/management/activation_keys/new
[12]: https://matrix.to/#/#mkosi:matrix.org
[13]: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
[14]: tmp.1bzWuYb2vw#a08aaa7d-ee14-4565-80a0-e3d19b21ad26-link

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[#]: subject: "Building RHEL and RHEL UBI images with mkosi"
[#]: via: "https://fedoramagazine.org/create-images-directly-from-rhel-and-rhel-ubi-package-using-mkosi/"
[#]: author: "Zbigniew Jędrzejewski-Szmek https://fedoramagazine.org/author/zbyszek/"
[#]: collector: "lujun9972/lctt-scripts-1700446145"
[#]: translator: "GlassFoxowo"
[#]: reviewer: " "
[#]: publisher: " "
[#]: url: " "
使用 mkosi 构建 RHEL 和 RHEL UBI 镜像
======
![][1]
图片： [Saad Salim][2] 发布于 [Unsplash][3]
mkosi 是一个轻量级工具，用于从发行包构建镜像。本文介绍如何使用 mkosi 从 RHEL(Red Hat Enterprise Linux) 和RHEL <ruby>[通用基础镜像][4]<rt>Universal Base Image</rt></ruby>（UBI） 的软件包构建镜像。RHEL UBI 是 RHEL的一个子集，可以在没有订阅的情况下免费使用。
### mkosi 特性
mkosi 支持一些输出格式，但最重要的是 <ruby>[可发现磁盘镜像][4]<rt>Discoverable Disk Images</rt></ruby>（DDI）。相同的 DDI 可用于引导容器、或运行在虚拟机、抑或是复制到 U 盘以引导真机，然后从 U 盘复制到磁盘以引导系统。该镜像具有标准化的布局和描述其用途的元数据。
mkosi 依赖其他工具来完成大部分工作：使用 _systemd-repart_ 在磁盘镜像上创建分区，使用 _mkfs.btrfs_ / _mkfs.ext4_ / _mkfs.xfs_ /… 编写文件系统，并使用 _dnf_ / _apt_ / _pacman_ / _zypper_ 下载和解压包。
mkosi 支持一系列发行版：Debian 和 Ubuntu,Arch Linux,OpenSUSE，当然还包括 Fedora,CentOS Stream 及其衍生版本，以及最近的 RHEL UBI 和 RHEL 。由于实际的”重活“是由其他工具完成的，mkosi 可以进行交叉构建。这意味着可以使用一个发行版构建各种其他发行版的镜像。唯一的要求是主机上安装了相应的工具。Fedora 对于 _apt_、_pacman_ 和 _zypper_ 有本机包，因此它为使用 mkosi 构建任何其他发行版提供了良好的基础。
还有一些巧妙的功能：镜像可以由非特权用户创建，或者在没有设备文件的容器中创建，特别是没有对回环设备的访问权限。它还可以在没有特权的情况下将这些镜像启动为虚拟机（使用 _qemu_）。
配置是声明性的，非常容易创建。使用 _systemd-repart_ 创建磁盘分区，并使用 _repart.d_ 配置文件定义应该如何完成此操作。
有关更多详细信息，请参见 Daan DeMeyer 在 All Systems Go 大会上的两个演讲：[systemd-repart: Building Discoverable Disk Images][5] 和 [mkosi: Building Bespoke Operating System Images][6]。
### 项目目标
mkosi 的一个目标是允许对软件项目进行针对不同发行版的测试。它将为一个发行版创建一个镜像（使用该发行版的软件包），然后将软件项目编译并安装到该镜像中，插入不属于软件包的额外文件。但是，首个阶段，即从软件包创建镜像的过程，本身就是有用的。这是我们将首先展示的内容。
我们[1][7]最近添加了对 RHEL 和 RHEL UBI 的支持。让我们从 RHEL UBI 开始，只构建一个由发行软件包组成的镜像。
请注意，下面的示例要求 mkosi 19，而且不适用于更早的版本。
### 带有Shell的基本RHEL UBI镜像
```
$ mkdir -p mkosi.cache
$ mkosi \
-d rhel-ubi \
-t directory \
-p bash,coreutils,util-linux,systemd,rpm \
--autologin
```
上面的命令指定了发行版 'rhel-ubi'，输出格式 'directory'，并请求安装软件包 _bash_、_coreutils_、…、_rpm_。_rpm_ 通常不需要在镜像内部，但在这里用于内省会很有用。我们还启用了以 root 用户自动登录。
在启动构建之前，我们创建了缓存目录 _mkosi.cache_。当存在缓存目录时，mkosi 会自动使用它来持久化下载的 RPM 包。这将使相同软件包集合的后续调用速度更快。
然后，我们可以使用 _systemd-nspawn_ 将此镜像作为容器启动：
```
$ sudo mkosi \
-d rhel-ubi \
-t directory \
boot
```
```
systemd 252-14.el9_2.3 running in system mode (+PAM +AUDIT +SELINUX -APPARMOR +IMA +SMACK +SECCOMP +GCRYPT +GNUTLS +OPENSSL +ACL +BLKID +CURL +ELFUTILS -FIDO2 +IDN2 -IDN -IPTC +KMOD +LIBCRYPTSETUP +LIBFDISK +PCRE2 -PWQUALITY +P11KIT -QRENCODE +TPM2 +BZIP2 +LZ4 +XZ +ZLIB +ZSTD -BPF_FRAMEWORK +XKBCOMMON +UTMP +SYSVINIT default-hierarchy=unified)
Detected virtualization systemd-nspawn.
Detected architecture x86-64.
Detected first boot.
Red Hat Enterprise Linux 9.2 (Plow)
...
[ OK ] Created slice Slice /system/getty.
[ OK ] Created slice Slice /system/modprobe.
[ OK ] Created slice User and Session Slice.
...
[ OK ] Started User Login Management.
[ OK ] Reached target Multi-User System.
Red Hat Enterprise Linux 9.2 (Plow)
Kernel 6.5.6-300.fc39.x86_64 on an x86_64
image login: root (automatic login)
[root@image ~]# rpm -q rpm systemd
rpm-4.16.1.3-22.el9.x86_64
systemd-252-14.el9_2.3.x86_64
```
正如前面提到的，此镜像可以用于启动虚拟机。但在此设置下，这是不可能的——我们的镜像没有内核。事实上，RHEL UBI 根本不提供内核，因此我们无法使用它进行引导（无论是在虚拟机上还是在裸机上）。
### 创建镜像
我一开始说是要创建镜像，但到目前为止我们只有一个目录。让我们开始实际创建一个镜像：
```
$ mkosi \
-d rhel-ubi \
-t disk \
-p bash,coreutils,util-linux,systemd,rpm \
--autologin
```
这将生成 _image.raw_，一个带有 GPT 分区表和单个根分区（用于本机架构）的磁盘镜像。
```
$ sudo systemd-dissect image.raw
Name: image.raw
Size: 301.0M
Sec. Size: 512
Arch.: x86-64
Image UUID: dcbd6499-409e-4b62-b251-e0dd15e446d5
OS Release: NAME=Red Hat Enterprise Linux
VERSION=9.2 (Plow)
ID=rhel
ID_LIKE=fedora
VERSION_ID=9.2
PLATFORM_ID=platform:el9
PRETTY_NAME=Red Hat Enterprise Linux 9.2 (Plow)
ANSI_COLOR=0;31
LOGO=fedora-logo-icon
CPE_NAME=cpe:/o:redhat:enterprise_linux:9::baseos
HOME_URL=https://www.redhat.com/
DOCUMENTATION_URL=https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9
BUG_REPORT_URL=https://bugzilla.redhat.com/
REDHAT_BUGZILLA_PRODUCT=Red Hat Enterprise Linux 9
REDHAT_BUGZILLA_PRODUCT_VERSION=9.2
REDHAT_SUPPORT_PRODUCT=Red Hat Enterprise Linux
REDHAT_SUPPORT_PRODUCT_VERSION=9.2
Use As: ✗ bootable system for UEFI
✓ bootable system for container
✗ portable service
✗ initrd
✗ sysext extension for system
✗ sysext extension for initrd
✗ sysext extension for portable service
RW DESIGNATOR PARTITION UUID PARTITION LABEL FSTYPE ARCHITECTURE VERITY GROWFS NODE PARTNO
rw root 1236e211-4729-4561-a6fc-9ef8f18b828f root-x86-64 xfs x86-64 no yes /dev/loop0p1 1
```
好的，我们现在有一个镜像，镜像中包含了一些来自 RHEL UBI 软件包的内容。我们如何在其上加点我们自己的东西呢？
### 使用自己的文件扩展镜像
有几种方法可以扩展镜像，包括从头开始编译某些东西。但在那之前，让我们做一些更简单的事情，将一个现成的文件系统注入到镜像中：
```
$ mkdir -p mkosi.extra/srv/www/content
$ cat >mkosi.extra/srv/www/content/index.html <<'EOF'
<h1>Hello, World!</h1>
EOF
```
现在，该镜像将包含 _/srv/www/content/index.html_。
这种方法用于注入额外的配置或简单的程序。
### 从源代码构建
现在让我们过一遍完整流程，从源代码构建一些东西。例如，一个简单的 Meson 项目，有一个单独的 C 文件：
```
$ cat >hello.c <<'EOF'
#include <stdio.h>
int main(int argc, char **argv) {
char buf[1024];
FILE *f = fopen("/srv/www/content/index.html", "re");
size_t n = fread(buf, 1, sizeof buf, f);
fwrite(buf, 1, n, stdout);
fclose(f);
return 0;
}
EOF
$ cat >meson.build <<'EOF'
project('hello', 'c')
executable('hello', 'hello.c',
install: true)
EOF
```
```
$ cat >mkosi.build <<'EOF'
set -ex
mkosi-as-caller rm -rf "$BUILDDIR/build"
mkosi-as-caller meson setup "$BUILDDIR/build" "$SRCDIR"
mkosi-as-caller meson compile -C "$BUILDDIR/build"
meson install -C "$BUILDDIR/build" --no-rebuild
EOF
$ chmod +x mkosi.build
```
总结一下：我们有一些源代码（_hello.c_），一个构建系统配置文件（_meson.build_），以及一个由 _mkosi_ 调用的胶水脚本（_mkosi.build_）。对于实际的项目，也会有相同的元素，只是更加复杂。
这个脚本需要一些解释。mkosi 在创建镜像时使用用户命名空间。这允许包管理器（例如 _dnf_）安装由不同用户拥有的文件，即使它是由一个普通非特权用户调用的。我们使用 _mkosi-as-caller_ 切换回调用者以进行编译。这样，在 $BUILDDIR 下编译期间创建的文件将由调用者拥有。
现在让我们使用我们的程序构建镜像。与之前的调用相比，我们需要额外的软件包：_meson_、_gcc_。由于我们现在有了构建脚本，mkosi 将执行两个构建阶段：首先创建一个构建镜像，并在其中调用构建脚本，将安装产物存储在一个临时目录中，然后构建最终镜像，并将安装产物注入其中。（mkosi 设置 $DESTDIR，_meson install_ 自动使用 $DESTDIR，因此并不需要我们明确指定。）
```
$ mkosi \
-d rhel-ubi \
-t disk \
-p bash,coreutils,util-linux,systemd,rpm \
--autologin \
--build-package=meson,gcc \
--build-dir=mkosi.builddir \
--build-script=mkosi.build \
-f
```
此时，我们有了带有自定义载荷的镜像 _image.raw_。我们可以启动我们新创建的可执行文件作为 shell 命令：
```
$ sudo mkosi -d rhel-ubi -t directory shell hello
<h1>Hello, World!</h1>
```
### 获取 RHEL 的开发者订阅
RHEL UBI 主要用作容器构建的基础层。它提供了有限的软件包（约 1500 个）。现在让我们切换到完整的 RHEL 安装。
获取 RHEL 的最简单方法是使用 [开发者许可证][8]。它提供了权限注册 16 个运行 RHEL 的物理或虚拟节点，并提供自助式支持。
首先，[创建一个账户][9]。然后，转到 [管理页面][10] 并确保启用了“用于 Red Hat 订阅管理的简化内容访问”。接下来，[创建一个新的激活密钥][11]，选择“ Red Hat 个人开发者订阅”。记下显示的组织 ID。在下面，我们将使用密钥名称和组织 ID 分别表示为 $KEY_NAME 和 $ORGANIZATION_ID。
现在，我们准备使用 RHEL 内容：
```
$ sudo dnf install subscription-manager
$ sudo subscription-manager register \
--org $ORGANIZATION_ID --activationkey $KEY_NAME
```
### 使用 RHEL 构建镜像
在之前的示例中，我们通过参数开关指定了所有配置。这对于快速开发很友好，但可能在情况复杂时变得难以处理。RHEL 是一个严肃的发行版，所以让我们改为使用配置文件：
```
$ cat >mkosi.conf <<'EOF'
[Output]
Format=directory
Output=rhel-directory
[Distribution]
Distribution=rhel
[Content]
Packages=
bash
coreutils
util-linux
systemd
systemd-boot
systemd-udev
kernel-core
Bootable=yes
Bootloader=uki
Autologin=yes
WithDocs=no
EOF
```
首先，让我们检查一下一切是否正常：
```
$ mkosi summary
```
现在让我们构建镜像（呃，或者说，目录）：
```
$ mkosi build
$ mkosi qemu
```
```
Welcome to Red Hat Enterprise Linux 9.2 (Plow)!
[ OK ] Created slice Slice /system/modprobe.
[ OK ] Reached target Initrd Root Device.
[ OK ] Reached target Initrd /usr File System.
[ OK ] Reached target Local Integrity Protected Volumes.
[ OK ] Reached target Local File Systems.
[ OK ] Reached target Path Units.
[ OK ] Reached target Remote Encrypted Volumes.
[ OK ] Reached target Remote Verity Protected Volumes.
[ OK ] Reached target Slice Units.
[ OK ] Reached target Swaps.
...
[ OK ] Listening on Journal Socket.
[ OK ] Listening on udev Control Socket.
[ OK ] Listening on udev Kernel Socket.
...
Red Hat Enterprise Linux 9.2 (Plow)
Kernel 5.14.0-284.30.1.el9_2.x86_64 on an x86_64
localhost login: root (automatic login)
[root@localhost ~]#
```
很好，我们将“镜像”构建为一个带有文件系统树的目录，并在虚拟机中引导了它。
在引导的虚拟机中，_findmnt /_ 显示根文件系统是 virtiofs。这是一个虚拟文件系统，将主机的目录暴露给客户机。我们其实也可以构建一个更传统的镜像，其中包含文件系统和文件内的分区表，但 目录+virtiofs 对于开发来说更快且更友好。
我们刚刚引导的镜像未注册。要允许从镜像“内部”下载更新，我们必须将 _yum_ 、_subscription-manager_ 和 _NetworkManager_ 添加到软件包列表，并在下载任何更新之前以与上述相同的方式调用 _subscription-manager_。在这之后，我们在基本仓库中就有大约 4500 个软件包可用，并且还有一些包含更多专业软件包的额外仓库。
### 最后
今天就是这些了。如果您有问题，可以在 Matrix 上找到我们，地址为 [#mkosi:matrix.org][12]，或者在 [systemd 邮件列表][13] 上找到我们。
--
1. Daan DeMeyer、Lukáš Nykrýn、Michal Sekletár、Zbigiew Jędrzejewski-Szmek [↩︎][14]
--------------------------------------------------------------------------------
via: https://fedoramagazine.org/create-images-directly-from-rhel-and-rhel-ubi-package-using-mkosi/
作者：[Zbigniew Jędrzejewski-Szmek][a]
选题：[lujun9972][b]
译者：[GlassFoxowo](https://github.com/GlassFoxowo-Dev)
校对：[校对者ID](https://github.com/校对者ID)
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
[a]: https://fedoramagazine.org/author/zbyszek/
[b]: https://github.com/lujun9972
[1]: https://fedoramagazine.org/wp-content/uploads/2023/10/building_w_mkosi-816x345.jpg
[2]: https://unsplash.com/@saadx?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash
[3]: https://unsplash.com/photos/aerial-photo-of-people-in-park-at-daytime-PqRvLsjD_TU?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash
[4]: https://uapi-group.org/specifications/specs/discoverable_disk_image/
[5]: https://media.ccc.de/v/all-systems-go-2023-191-systemd-repart-building-discoverable-disk-images
[6]: https://media.ccc.de/v/all-systems-go-2023-190-mkosi-building-bespoke-operating-system-images
[7]: tmp.1bzWuYb2vw#a08aaa7d-ee14-4565-80a0-e3d19b21ad26
[8]: https://developers.redhat.com/articles/faqs-no-cost-red-hat-enterprise-linux
[9]: https://developers.redhat.com/register
[10]: https://access.redhat.com/management
[11]: https://access.redhat.com/management/activation_keys/new
[12]: https://matrix.to/#/#mkosi:matrix.org
[13]: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
[14]: tmp.1bzWuYb2vw#a08aaa7d-ee14-4565-80a0-e3d19b21ad26-link