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guix/gnu/system/vm.scm
Mathieu Othacehe 0233583aa4
system: vm: Change the writable image name. 
* gnu/system/vm.scm (system-qemu-image/shared-store-script): Change it.
2022-01-14 12:26:07 +01:00

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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 Christine Lemmer-Webber <cwebber@dustycloud.org>
;;; Copyright © 2016, 2017 Leo Famulari <leo@famulari.name>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2017 Marius Bakke <mbakke@fastmail.com>
;;; Copyright © 2018 Chris Marusich <cmmarusich@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu system vm)
#:use-module (guix config)
#:use-module (guix store)
#:use-module (guix gexp)
#:use-module (guix derivations)
#:use-module (guix packages)
#:use-module (guix monads)
#:use-module (guix records)
#:use-module (guix modules)
#:use-module (guix utils)
#:use-module (gcrypt hash)
#:use-module (guix base32)
#:use-module ((guix self) #:select (make-config.scm))
#:use-module ((gnu build marionette)
#:select (qemu-command))
#:use-module (gnu packages base)
#:use-module (gnu packages bootloaders)
#:use-module (gnu packages cdrom)
#:use-module (gnu packages compression)
#:use-module (gnu packages guile)
#:autoload (gnu packages gnupg) (guile-gcrypt)
#:use-module (gnu packages gawk)
#:use-module (gnu packages bash)
#:use-module (gnu packages virtualization)
#:use-module (gnu packages disk)
#:use-module (gnu packages linux)
#:use-module (gnu bootloader)
#:use-module (gnu bootloader grub)
#:use-module (gnu image)
#:use-module (gnu system image)
#:use-module (gnu system linux-container)
#:use-module (gnu system linux-initrd)
#:use-module (gnu bootloader)
#:use-module (gnu system file-systems)
#:use-module (gnu system)
#:use-module (gnu services)
#:use-module (gnu services base)
#:use-module (gnu system uuid)
#:use-module ((srfi srfi-1) #:hide (partition))
#:use-module (srfi srfi-26)
#:use-module (rnrs bytevectors)
#:use-module (ice-9 match)
#:export (virtualized-operating-system
system-qemu-image/shared-store-script
virtual-machine
virtual-machine?))
;;; Commentary:
;;;
;;; Tools to evaluate build expressions within virtual machines.
;;;
;;; Code:
;; By default, the msize value is 8 KiB, which according to QEMU is
;; insufficient and would degrade performance. The msize value should roughly
;; match the bandwidth of the system's IO (see:
;; https://wiki.qemu.org/Documentation/9psetup#msize). Use 100 MiB as a
;; conservative default.
(define %default-msize-value (* 100 (expt 2 20))) ;100 MiB
(define %linux-vm-file-systems
;; File systems mounted for 'derivation-in-linux-vm'. These are shared with
;; the host over 9p.
;;
;; The 9p documentation says that cache=loose is "intended for exclusive,
;; read-only mounts", without additional details. It's much faster than the
;; default cache=none, especially when copying and registering store items.
;; Thus, use cache=loose, except for /xchg where we want to ensure
;; consistency.
(list (file-system
(mount-point (%store-prefix))
(device "store")
(type "9p")
(needed-for-boot? #t)
(flags '(read-only))
(options (format #f "trans=virtio,cache=loose,msize=~a"
%default-msize-value))
(check? #f))
(file-system
(mount-point "/xchg")
(device "xchg")
(type "9p")
(needed-for-boot? #t)
(options (format #f "trans=virtio,msize=~a" %default-msize-value))
(check? #f))
(file-system
(mount-point "/tmp")
(device "tmp")
(type "9p")
(needed-for-boot? #t)
(options (format #f "trans=virtio,cache=loose,msize=~a"
%default-msize-value))
(check? #f))))
;;;
;;; VMs that share file systems with the host.
;;;
(define (file-system->mount-tag fs)
"Return a 9p mount tag for host file system FS."
;; QEMU mount tags must be ASCII, at most 31-byte long, cannot contain
;; slashes, and cannot start with '_'. Compute an identifier that
;; corresponds to the rules.
(string-append "TAG"
(string-drop (bytevector->base32-string
(sha1 (string->utf8 fs)))
4)))
(define (mapping->file-system mapping)
"Return a 9p file system that realizes MAPPING."
(match mapping
(($ <file-system-mapping> source target writable?)
(file-system
(mount-point target)
(device (file-system->mount-tag source))
(type "9p")
(flags (if writable? '() '(read-only)))
(options (string-append "trans=virtio"
(if writable? "" ",cache=loose")
",msize=" (number->string %default-msize-value)))
(check? #f)
(create-mount-point? #t)))))
(define* (virtualized-operating-system os mappings
#:key (full-boot? #f) volatile?)
"Return an operating system based on OS suitable for use in a virtualized
environment with the store shared with the host. MAPPINGS is a list of
<file-system-mapping> to realize in the virtualized OS."
(define user-file-systems
;; Remove file systems that conflict with those added below, or that are
;; normally bound to real devices.
(remove (lambda (fs)
(let ((target (file-system-mount-point fs))
(source (file-system-device fs)))
(or (string=? target (%store-prefix))
(string=? target "/")
(and (string? source)
(string-prefix? "/dev/" source))
;; Labels and UUIDs are necessarily invalid in the VM.
(and (file-system-mount? fs)
(or (file-system-label? source)
(uuid? source))))))
(operating-system-file-systems os)))
(define virtual-file-systems
(cons (file-system
(mount-point "/")
(device "/dev/vda1")
(type "ext4"))
(append (map mapping->file-system mappings)
user-file-systems)))
(operating-system (inherit os)
;; XXX: Until we run QEMU with UEFI support (with the OVMF firmware),
;; force the traditional i386/BIOS method.
;; See <https://bugs.gnu.org/28768>.
(bootloader (bootloader-configuration
(inherit (operating-system-bootloader os))
(bootloader grub-bootloader)
(targets '("/dev/vda"))))
(initrd (lambda (file-systems . rest)
(apply (operating-system-initrd os)
file-systems
#:volatile-root? volatile?
rest)))
;; Disable swap.
(swap-devices '())
;; XXX: When FULL-BOOT? is true, do not add a 9p mount for /gnu/store
;; since that would lead the bootloader config to look for the kernel and
;; initrd in it.
(file-systems (if full-boot?
virtual-file-systems
(cons
(file-system
(inherit (mapping->file-system %store-mapping))
(needed-for-boot? #t))
virtual-file-systems)))))
(define* (common-qemu-options image shared-fs
#:key rw-image?)
"Return the a string-value gexp with the common QEMU options to boot IMAGE,
with '-virtfs' options for the host file systems listed in SHARED-FS."
(define (virtfs-option fs)
#~(format #f "-virtfs local,path=~s,security_model=none,mount_tag=~s"
#$fs #$(file-system->mount-tag fs)))
#~(;; Only enable kvm if we see /dev/kvm exists.
;; This allows users without hardware virtualization to still use these
;; commands.
#$@(if (file-exists? "/dev/kvm")
'("-enable-kvm")
'())
"-no-reboot"
"-object" "rng-random,filename=/dev/urandom,id=guix-vm-rng"
"-device" "virtio-rng-pci,rng=guix-vm-rng"
#$@(map virtfs-option shared-fs)
#$@(if rw-image?
#~((format #f "-drive file=~a,if=virtio" #$image))
#~((format #f "-drive file=~a,if=virtio,cache=writeback,werror=report,readonly=on"
#$image)))))
(define* (system-qemu-image/shared-store-script os
#:key
(system (%current-system))
(target (%current-target-system))
(qemu qemu)
(graphic? #t)
(volatile? #t)
(memory-size 512)
(mappings '())
full-boot?
(disk-image-size
(* (if full-boot? 500 70)
(expt 2 20)))
(options '()))
"Return a derivation that builds a script to run a virtual machine image of
OS that shares its store with the host. The virtual machine runs with
MEMORY-SIZE MiB of memory.
MAPPINGS is a list of <file-system-mapping> specifying mapping of host file
systems into the guest.
When FULL-BOOT? is true, the returned script runs everything starting from the
bootloader; otherwise it directly starts the operating system kernel. When
VOLATILE? is true, an overlay is created on top of a read-only
storage. Otherwise the storage is made persistent. The DISK-IMAGE-SIZE
parameter specifies the size in bytes of the root disk image; it is mostly
useful when FULL-BOOT? is true."
(mlet* %store-monad ((os -> (virtualized-operating-system
os mappings
#:full-boot? full-boot?
#:volatile? volatile?))
(base-image -> (system-image
(image
(inherit
(raw-with-offset-disk-image))
(operating-system os)
(size disk-image-size)
(shared-store?
(and (not full-boot?) volatile?))
(volatile-root? volatile?)))))
(define kernel-arguments
#~(list #$@(if graphic? #~() #~("console=ttyS0"))
#+@(operating-system-kernel-arguments os "/dev/vda1")))
(define rw-image
#~(format #f "/tmp/guix-image-~a" (basename #$base-image)))
(define qemu-exec
#~(list #+(file-append qemu "/bin/"
(qemu-command (or target system)))
;; Tells qemu to use the terminal it was started in for IO.
#$@(if graphic? '() #~("-nographic"))
#$@(if full-boot?
#~()
#~("-kernel" #$(operating-system-kernel-file os)
"-initrd" #$(file-append os "/initrd")
(format #f "-append ~s"
(string-join #$kernel-arguments " "))))
#$@(common-qemu-options (if volatile? base-image rw-image)
(map file-system-mapping-source
(cons %store-mapping mappings))
#:rw-image? (not volatile?))
"-m " (number->string #$memory-size)
#$@options))
(define builder
#~(call-with-output-file #$output
(lambda (port)
(format port "#!~a~%"
#+(file-append bash "/bin/sh"))
(when (not #$volatile?)
(format port "~a~%"
#$(program-file "copy-image"
#~(unless (file-exists? #$rw-image)
(copy-file #$base-image #$rw-image)
(chmod #$rw-image #o640)))))
(format port "exec ~a \"$@\"~%"
(string-join #$qemu-exec " "))
(chmod port #o555))))
(gexp->derivation "run-vm.sh" builder)))
;;;
;;; High-level abstraction.
;;;
(define-record-type* <virtual-machine> %virtual-machine
make-virtual-machine
virtual-machine?
(operating-system virtual-machine-operating-system) ;<operating-system>
(qemu virtual-machine-qemu ;<package>
(default qemu-minimal))
(volatile? virtual-machine-volatile? ;Boolean
(default #t))
(graphic? virtual-machine-graphic? ;Boolean
(default #f))
(memory-size virtual-machine-memory-size ;integer (MiB)
(default 256))
(disk-image-size virtual-machine-disk-image-size ;integer (bytes)
(default 'guess))
(port-forwardings virtual-machine-port-forwardings ;list of integer pairs
(default '())))
(define-syntax virtual-machine
(syntax-rules ()
"Declare a virtual machine running the specified OS, with the given
options."
((_ os) ;shortcut
(%virtual-machine (operating-system os)))
((_ fields ...)
(%virtual-machine fields ...))))
(define (port-forwardings->qemu-options forwardings)
"Return the QEMU option for the given port FORWARDINGS as a string, where
FORWARDINGS is a list of host-port/guest-port pairs."
(string-join
(map (match-lambda
((host-port . guest-port)
(string-append "hostfwd=tcp::"
(number->string host-port)
"-:" (number->string guest-port))))
forwardings)
","))
(define-gexp-compiler (virtual-machine-compiler (vm <virtual-machine>)
system target)
(match vm
(($ <virtual-machine> os qemu volatile? graphic? memory-size
disk-image-size ())
(system-qemu-image/shared-store-script os
#:system system
#:target target
#:qemu qemu
#:graphic? graphic?
#:volatile? volatile?
#:memory-size memory-size
#:disk-image-size
disk-image-size))
(($ <virtual-machine> os qemu volatile? graphic? memory-size
disk-image-size forwardings)
(let ((options
`("-nic" ,(string-append
"user,model=virtio-net-pci,"
(port-forwardings->qemu-options forwardings)))))
(system-qemu-image/shared-store-script os
#:system system
#:target target
#:qemu qemu
#:graphic? graphic?
#:volatile? volatile?
#:memory-size memory-size
#:disk-image-size
disk-image-size
#:options options)))))
;;; vm.scm ends here
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