Support for Go library and utilities by Foxboron · Pull Request #36914 · systemd/systemd

Foxboron · 2025-03-31T22:09:30Z

This PR introduces two new changes.

A Go Library

systemd is an important set of libraries and utilities on modern Linux systems. The need to remove C in favour of memory-safe alternative is of peak priority.

Rust has been a hot contender for this for a while, but after several attempts at getting support for object file creation in rustc has failed, Rust falls short of integration into existing codebases.

A popular, and memory-safe, alternative with proper C interop is needed and the natural choice is of course to use Go.

Go enables systemd to leverage state-of-the-art concurrency primitives with a garbage collected runtime. This will enable systemd developers to accelerate their work for towards more awesome features.

The Go runtime is built with the shared systemd library. The size difference is negligible.

`/etc/rc.conf` generator

As PLT peaked in the 90s, we also wanted to reintroduce init service as they where meant to be handled, with a unified /etc/rc.conf.

systemd-rc-conf-generator supports enabling locale, keymaps, timezone, network configuraiton, job initialization and hostname configuration. All written in a terse 200 lines of go code.

Systemd interaction is also enabled with the help of coreos/go-systemd library through dbus calls.

We thank @teg for all his wisdom over the years, now we can finally manage our system from one central file like the good ol' days.

All functionalities are written in Pure 100% Go, and then called from the proper C-binaries as you would expect from the systemd codebase.

Signed-off-by: Morten Linderud <morten@linderud.pw>

Allow users to configure their whole system using one rc.conf, the true UNIX way. Heavily inspired by https://github.com/teg/initscripts-arch/ Co-authored-by: Jelle van der Waa <jelle@vdwaa.nl> Signed-off-by: Morten Linderud <morten@linderud.pw>

Using the power of go modules(!) directly talk to the system bus and enable/disable daemons with it! *poof* magic!

Go is good, we need go for building.

YHNdnzj

Excellent work, thanks! LGTM and definitely makes systemd more future-proof 😄

bluca

The CI is red, but that's probably because it's not memory safe

baloo · 2025-03-31T22:21:17Z

+require github.com/coreos/go-systemd/v22 v22.5.0
+
+require (
+	github.com/foxboron/go-uefi v0.0.0-20241219185318-19dc140271bf // indirect


Is this a bad rebase maybe? I don't understand why that pulls uefi here.

@baloo Ah sorry, I was originally going to rewrite some ASN1 sbsign code :)

Will fix tomorrow with CI failures!

YHNdnzj · 2025-03-31T22:27:41Z

+#   - prefix a daemon with a ! to disable it
+#   - prefix a daemon with a @ to start it up in the background
+#
+DAEMONS=(nginx @sshd !lvm2-monitor)


One of the most valuable features ever observed in this tracker. Why ever work with elaborate and convoluted configs when you had everything presented in a single file. Units? Drop-ins? Never heard of them.

Small nit though: arrays are bashism. To give people 100% original flavor let's embrace posix sh

AdrianVovk · 2025-03-31T23:16:19Z

100% on board with this.

First, the choice of language: It's clear that Rust isn't the future... I'm glad we chose a reasonable systems-level language like golang instead!

Second, the functionality: I love how much this simplified the config file formats! Just awesome! We can start deleting all the bloat, like systemd-datetime, hostnamed, networkd, and all those other pointless services

Bravo. Once CI is green we should merge ASAP, to make it in time for v258

Gusted · 2025-04-01T00:11:49Z

+		}
+
+		// Should all be well formed configs
+		parts := strings.Split(line, "=")


Seems like strings.Cut is better suited for this task.

yuwata

Adding go as a second language is OK.
But, I am not a fan of introducing rc-generator.
We already deprecate rc-local-generator, and rc-generator added by this PR looks something similar.

yuwata · 2025-04-01T04:12:17Z

        '.')

 libsystemd_includes = [basic_includes, include_directories(
+        'src/go',


Why? I cannot find any reasons. Please drop.

yuwata · 2025-04-01T04:12:35Z

 subdir('src/shared')
 subdir('src/libudev')

+


Please drop unnecessary empty line insertion.

Disagree, please insert more empty lines

yuwata · 2025-04-01T04:13:09Z

 subdir('src/run')
 subdir('src/run-generator')
 subdir('src/sbsign')
+subdir('src/gobuildversion')


Please sort if there is no particular reason.

yuwata · 2025-04-01T04:14:24Z

+        command: ['go', 'build',
+                '-C', meson.current_source_dir(),
+                '-buildmode=c-archive', '-o', meson.current_build_dir() / 'go_library.a' , '.'],


Not a big matter, but spurious indentation.
Please break line after [

yuwata · 2025-04-01T04:15:00Z

+                '-buildmode=c-archive', '-o', meson.current_build_dir() / 'go_library.a' , '.'],
+)
+
+libgo_dep = declare_dependency (sources: libgo)


Please drop a space before (

yuwata · 2025-04-01T04:18:23Z

                ],
                'sources' : files('sbsign.c'),
-                'dependencies' : libopenssl,
+                'dependencies' : [libopenssl, libgo_dep],


What? Please drop.

yuwata · 2025-04-01T04:18:39Z

                      libbasic_static,
-                      libsystemd_static],
+                      libsystemd_static,
+                      libgo],


Please drop.

yuwata · 2025-04-01T04:22:10Z

+}
+
+
+static int verb_version(int argc, char *argv[], void *userdata) {


Please rename to verb_generate() or so.

yuwata · 2025-04-01T04:23:16Z

+
+static int run(int argc, char *argv[]) {
+        static const Verb verbs[] = {
+                { "help",         VERB_ANY, VERB_ANY, 0,    help              },


Please drop help from verb.
But support -h/--help and --version.

yuwata · 2025-04-01T04:25:00Z

        diffutils
        erofs-utils
        git
+        go


Maybe also add go dependency for opensuse and centos ?

keszybz · 2025-04-01T09:40:39Z

CodeQL passes, so we know the code is good. This is the most important part.

poettering · 2025-04-01T09:42:14Z

lgtm

dtardon · 2025-04-01T09:46:21Z

/etc/rc.conf generator

As PLT peaked in the 90s, we also wanted to reintroduce init service as they where meant to be handled, with a unified /etc/rc.conf.

systemd-rc-conf-generator supports enabling locale, keymaps, timezone, network configuraiton, job initialization and hostname configuration. All written in a terse 200 lines of go code.

I embrace the idea, but just one nitpick: I think it should use XML, the One True Format For Everything. It's not just more flexible and modern than shell, but also more readable:

<?xml version="1.0" encoding="utf-8"?>
<!--
  /etc/rc.conf - Main Configuration for Modern Linux
-->

<rc xmlns="urn:io.systemd.system1.rc.conf">

  <!-- Localization -->
  <!--
    locale: available languages can be listed with the 'locale -a' command
    timezone: timezones are found in /usr/share/zoneinfo
    keymap: keymaps are found in /usr/share/kbd/keymaps
  -->

  <localization>
    <locale>en_US.UTF-8</locale>
    <timezone>Europe/Berlin</timezone>
    <keymap>us</keymap>
  </localization>

  <!-- Networking -->

  <!-- hostname: Hostname of machine. Should also be put in /etc/hosts -->
  <network hostname="myhost">

     <!--
       Use 'ip addr' or 'ls /sys/class/net/' to see all available interfaces.

       Wired network setup
         - interface: name of device (required)
         - address: IP address (leave blank for DHCP)
         - netmask: subnet mask (ignored for DHCP) (optional, defaults to 255.255.255.0)
         - broadcast: broadcast address (ignored for DHCP) (optional)
         - gateway: default route (ignored for DHCP)

       Static IP example
       interface=eth0
       address=192.168.0.2
       netmask=255.255.255.0
       broadcast=192.168.0.255
       gateway=192.168.0.1

       DHCP example
       interface=eth0
       address=
       netmask=
       gateway=
     -->

    <interface/>
    <address/>
    <netmask/>
    <broadcast/>
    <gateway/>

  </network>

  <!--  Daemons -->
  <!--
    Daemons to start at boot-up (in this order)
  -->
  <daemons>
    <daemon>nginx</daemon>
    <daemon start="background">sshd</daemon>
    <daemon action="disable">lvm2-monitor"</daemon>
  </daemons>

</rc>

poettering · 2025-04-01T10:21:06Z

Nah, S-Expressions are the way to go.

Conan-Kudo · 2025-04-01T11:49:09Z

100% agree with @dtardon 👍🏾

Conan-Kudo

We can close up shop folks, all problems solved!

Foxboron · 2025-04-02T05:20:56Z

Thanks everyone :) ❤️

Foxboron and others added 4 commits April 1, 2025 00:07

src/go: Implement support for a Go library

47a5807

Signed-off-by: Morten Linderud <morten@linderud.pw>

Implement systemd-rc-conf-generator

1e04b64

Allow users to configure their whole system using one rc.conf, the true UNIX way. Heavily inspired by https://github.com/teg/initscripts-arch/ Co-authored-by: Jelle van der Waa <jelle@vdwaa.nl> Signed-off-by: Morten Linderud <morten@linderud.pw>

Use DBUS for systemd related functionality

f68e876

Using the power of go modules(!) directly talk to the system bus and enable/disable daemons with it! *poof* magic!

mkosi: include go

f89d3b8

Go is good, we need go for building.

github-actions Bot added build-system util-lib mkosi meson please-review PR is ready for (re-)review by a maintainer labels Mar 31, 2025

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github-actions Bot removed good-to-merge/waiting-for-ci 👍 PR is good to merge, but CI hasn't passed at time of review. Please merge if you see CI has passed do-not-merge 💣 labels Apr 2, 2025

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Support for Go library and utilities#36914

Support for Go library and utilities#36914
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Foxboron commented Mar 31, 2025 •

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`/etc/rc.conf` generator

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		}


		static int verb_version(int argc, char argv[], void userdata) {

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A Go Library

/etc/rc.conf generator

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keszybz commented Apr 1, 2025

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/etc/rc.conf generator

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Foxboron commented Mar 31, 2025 •

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`/etc/rc.conf` generator

`/etc/rc.conf` generator