aboutsummaryrefslogtreecommitdiff
path: root/gnu/system/vm.scm
blob: 8c27ff787d327677fe1bc84203df7a39479b5635 (about) (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013-2022 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

;;;
;;; 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)))

       ;; The 9p documentation says that cache=loose is "intended for
       ;; exclusive, read-only mounts", without additional details.  It's
       ;; faster than the default cache=none, especially when copying and
       ;; registering store items.  Thus, use cache=loose, except for writable
       ;; mounts, to ensure consistency.
       (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)))
    ;; The (QEMU-only) "cirrus" graphics driver is still expected by some
    ;; VPS with old QEMU versions.  See <https://bugs.gnu.org/36069>.
    (initrd-modules (let ((modules (operating-system-initrd-modules os)))
                      (if (member "cirrus" modules)
                          modules
                          (cons "cirrus" modules))))

    ;; 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,format=qcow2,if=virtio" #$image))
            #~((format #f "-drive file=~a,format=raw,if=virtio,cache=writeback,werror=report,readonly=on"
                       #$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 copy-image
      ;; Script that "copies" BASE-IMAGE to /tmp.  Make a copy-on-write image,
      ;; which is much cheaper than actually copying it.
      (program-file "copy-image"
                    (with-imported-modules '((guix build utils))
                      #~(begin
                          (use-modules (guix build utils))
                          (unless (file-exists? #$rw-image)
                            (invoke #+(file-append qemu "/bin/qemu-img")
                                    "create" "-b" #$base-image
                                    "-F" "raw" "-f" "qcow2" #$rw-image))))))

    (define builder
      #~(call-with-output-file #$output
          (lambda (port)
            (format port "#!~a~%"
                    #+(file-append bash "/bin/sh"))
            #$@(if volatile?
                   #~()
                   #~((format port "~a~%" #+copy-image)))
            (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