1virt-dib(1) Virtualization Support virt-dib(1)
2
6 virt-dib - Run diskimage-builder elements
7
9 virt-dib -B DIB-LIB [options] elements...
10
12 Virt-dib is a tool for using the elements of "diskimage-builder" to
13 build a new disk image, generate new ramdisks, etc.
14 Virt-dib is intended as safe replacement for "diskimage-builder" and
16 its "ramdisk-image-create" mode, see "COMPARISON WITH DISKIMAGE-
17 BUILDER" for a quick comparison with usage of "diskimage-builder".
18 "diskimage-builder" is part of the TripleO OpenStack project:
20 https://wiki.openstack.org/wiki/TripleO.
21
23 Build simple images of distributions
24 virt-dib \
25 -B /path/to/diskimage-builder/lib \
26 -p /path/to/diskimage-builder/elements \
27 --envvar DIB_RELEASE=jessie \
28 --name debian-jessie \
29 debian vm
30 This builds a Debian Jessie (8.x) disk image, suitable for running as
32 virtual machine, saved as debian-jessie.qcow2.
33 Build ramdisks
35 virt-dib \
36 -B /path/to/diskimage-builder/lib \
37 -p /path/to/diskimage-builder/elements \
38 --ramdisk \
39 --name ramdisk \
40 ubuntu deploy-ironic
41 This builds a ramdisk for the Ironic OpenStack component based on the
43 Ubuntu distribution.
44
46 --help
47 Display help.
48 -B PATH
50 Set the path to the library directory of "diskimage-builder". This
51 is usually the lib subdirectory in the sources and when installed,
52 and /usr/share/diskimage-builder/lib when installed in /usr.
53 This parameter is mandatory, as virt-dib needs to provide it for
55 the elements (as some of them might use scripts in it). Virt-dib
56 itself does not make use of the library directory.
57 --arch ARCHITECTURE
59 Use the specified architecture for the output image. The default
60 value is the same as the host running virt-dib.
61 Right now this option does nothing more than setting the "ARCH"
63 environment variable for the elements, and it’s up to them to
64 produce an image for the requested architecture.
65 --checksum
67 Generate checksum files for the generated image. The supported
68 checksums are MD5, and SHA256.
69 --colors
71 --colours
72 Use ANSI colour sequences to colourize messages. This is the
73 default when the output is a tty. If the output of the program is
74 redirected to a file, ANSI colour sequences are disabled unless you
75 use this option.
76 --debug LEVEL
78 Set the debug level to "LEVEL", which is a non-negative integer
79 number. The default is 0.
80 This debug level is different than what -x and -v set, and it
82 increases the debugging information printed out. Specifically,
83 this sets the "DIB_DEBUG_TRACE", and any value > 0 enables tracing
84 in the scripts executed.
85 --docker-target TARGET
87 Set the repository and tag for docker.
88 This is used only when the formats include "docker", and it is
90 required in that case.
91 --drive DISK
93 Add the specified disk to be used as helper drive where to cache
94 files of the elements, like disk images, distribution packages,
95 etc.
96 See "HELPER DRIVE".
98 --drive-format raw
100 --drive-format qcow2
101 Specify the format of the helper drive. If this flag is not given
102 then it is auto-detected from the drive itself.
103 If working with untrusted raw-format guest disk images, you should
105 ensure the format is always specified.
106 This option is used only if --drive is specified.
108 See "HELPER DRIVE".
110 -p PATH
112 --element-path PATH
113 Add a new path with elements. Paths are used in the same order as
114 the -p parameters appear, so a path specified first is looked
115 first, and so on.
116 Obviously, it is recommended to add the path to the own elements of
118 "diskimage-builder", as most of the other elements will rely on
119 them.
120 --extra-packages PACKAGE,...
122 Install additional packages in the image being built.
123 This relies on the "install-packages" binary provided by the
125 package management elements.
126 This option can be specified multiple times, each time with
128 multiple packages separated by comma.
129 --envvar VARIABLE
131 --envvar VARIABLE=VALUE
132 Carry or set an environment variable for the elements.
133 See "ENVIRONMENT VARIABLES" below for more information on the
135 interaction and usage of environment variables.
136 This option can be used in two ways:
138 --envvar VARIABLE
140 Carry the environment variable "VARIABLE". If it is not set,
141 nothing is exported to the elements.
142 --envvar VARIABLE=VALUE
144 Set the environment variable "VARIABLE" with value "VALUE" for
145 the elements, regardless whether an environment variable with
146 the same name exists.
147 This can be useful to pass environment variable without
149 exporting them in the environment where virt-dib runs.
150 --exclude-element ELEMENT
152 Ignore the specified element.
153 --exclude-script SCRIPT
155 Ignore any element script named "SCRIPT", whichever element it is
156 in.
157 This can be useful in case some script does not run well with virt-
159 dib, for example when they really need "diskimage-builder"'s
160 environment.
161 --formats FORMAT,...
163 Set the list of output formats, separating them with comma.
164 Supported formats are:
166 "docker"
168 Import the image to docker, running docker import. The target
169 for the image must be specified using --docker-target.
170 Please note this operation usually requires the docker service
172 to be enabled, otherwise it will fail. Furthermore, docker is
173 run using sudo(8), so make sure the user has the permissions to
174 run at least docker.
175 "qcow2" (enabled by default)
177 QEMU’s qcow2. This output format requires the "qemu-img" tool.
178 "raw"
180 Raw disk format.
181 "squashfs"
183 An squashfs filesystem, compressed with XZ. This output format
184 requires the "squashfs" feature; see also "AVAILABILITY" in
185 guestfs(3).
186 "tar"
188 An uncompressed tarball.
189 "tgz"
191 A tarball compressed with gzip.
192 "vhd"
194 "Virtual Hard Disk" disk image. This output format requires
195 the "vhd-util" tool.
196 Please note that the version of "vhd-util" tool needs to be
198 patched to support the "convert" subcommand, and to be
199 bootable. The patch is available here:
200 https://github.com/emonty/vhd-util/blob/master/debian/patches/citrix.
201 --fs-type FILESYSTEM
203 Set the filesystem type to use for the root filesystem. The
204 default is "ext4".
205 See also "guestfs_filesystem_available" in guestfs(3).
207 --image-cache DIRECTORY
209 Set the path in the host where cache the resources used by the
210 elements of the "extra-data.d" phase. The default is
211 ~/.cache/image-create.
212 Please note that most of the resources fetched in phases other than
214 "extra-data.d" will be cached in the helper drive specified with
215 --drive; see also "HELPER DRIVE".
216 --install-type TYPE
218 Specify the default installation type. Defaults to "source".
219 Set to "package" to use package based installations by default.
221 --machine-readable
223 --machine-readable=format
224 This option is used to make the output more machine friendly when
225 being parsed by other programs. See "MACHINE READABLE OUTPUT"
226 below.
227 -m MB
229 --memsize MB
230 Change the amount of memory allocated to the appliance. Increase
231 this if you find that the virt-dib execution runs out of memory.
232 The default can be found with this command:
234 guestfish get-memsize
236 --mkfs-options "OPTION STRING"
238 Add the specified options to mkfs(1), to be able to fine-tune the
239 root filesystem creation; the options are passed to the driver of
240 mfks(1), and not to mfks(1) itself. Note that --fs-type is used to
241 change the filesystem type.
242 You should use --mkfs-options at most once. To pass multiple
244 options, separate them with space, eg:
245 virt-dib ... --mkfs-options '-O someopt -I foo'
247 --network
249 --no-network
250 Enable or disable network access from the guest during the
251 installation.
252 Enabled is the default. Use --no-network to disable access.
254 The network only allows outgoing connections and has other minor
256 limitations. See "NETWORK" in virt-rescue(1).
257 This does not affect whether the guest can access the network once
259 it has been booted, because that is controlled by your hypervisor
260 or cloud environment and has nothing to do with virt-dib.
261 If you use --no-network, then the environment variable
263 "DIB_OFFLINE" is set to 1, signaling the elements that they should
264 use only cached resources when available. Note also that, unlike
265 with "diskimage-builder" where elements may still be able to access
266 to the network even with "DIB_OFFLINE=", under virt-dib network
267 will not be accessible at all.
268 --name NAME
270 Set the name of the output image file. The default is "image".
271 According to the chosen name, there will be the following in the
273 current directory:
274 $NAME.ext
276 For each output format, a file named after the output image
277 with the extension depending on the format; for example:
278 $NAME.qcow2, $NAME.raw, etc.
279 Not applicable in ramdisk mode, see "RAMDISK BUILDING".
281 $NAME.d
283 A directory containing any files created by the elements, for
284 example dib-manifests directory (created by the "manifests"
285 element), ramdisks and kernels in ramdisk mode, and so on.
286 $NAME.ext.checksum
288 When --checksum is specified, there will be files for each
289 supported checksum type; for example: $NAME.ext.md5,
290 $NAME.ext.sha256, etc.
291 Not applicable in ramdisk mode, see "RAMDISK BUILDING".
293 --no-delete-on-failure
295 Don’t delete the output files on failure to build. You can use
296 this to debug failures to run scripts.
297 The default is to delete the output files if virt-dib fails (or,
299 for example, some script that it runs fails).
300 --python PYTHON
302 Specify a different Python interpreter to use. Parts of
303 "diskimage-builder" are implemented in Python, and thus an
304 interpreter is needed.
305 "PYTHON" can either be an executable filename (e.g. python2, which
307 is then searched in $PATH), or a full path (e.g.
308 /usr/bin/python2). If not specified, the default value is python.
309 -q
311 --quiet
312 Don’t print ordinary progress messages.
313 --qemu-img-options option[,option,...]
315 Pass --qemu-img-options option(s) to the qemu-img(1) command to
316 fine-tune the output format. Options available depend on the
317 output format (see --formats) and the installed version of the
318 qemu-img program.
319 You should use --qemu-img-options at most once. To pass multiple
321 options, separate them with commas, eg:
322 virt-dib ... --qemu-img-options cluster_size=512,preallocation=metadata ...
324 --ramdisk
326 Set the ramdisk building mode.
327 See "RAMDISK BUILDING".
329 --ramdisk-element NAME
331 Set the name for the additional element added in ramdisk building
332 mode. The default is "ramdisk".
333 See "RAMDISK BUILDING".
335 --root-label LABEL
337 Set the label for the root filesystem in the created image.
338 Please note that some filesystems have different restrictions on
340 the length of their labels; for example, on "ext2/3/4" filesystems
341 labels cannot be longer than 16 characters, while on "xfs" they
342 have at most 12 characters.
343 The default depends on the actual filesystem for the root partition
345 (see --fs-type): on "xfs" is "img-rootfs", while "cloudimg-rootfs"
346 on any other filesystem.
347 --size SIZE
349 Select the size of the output disk, where the size can be specified
350 using common names such as "32G" (32 gigabytes) etc. The default
351 size is "5G".
352 To specify size in bytes, the number must be followed by the
354 lowercase letter b, eg: "--size 10737418240b".
355 See also virt-resize(1) for resizing partitions of an existing disk
357 image.
358 --skip-base
360 Skip the inclusion of the "base" element.
361 --smp N
363 Enable N ≥ 2 virtual CPUs for scripts to use.
364 -u Do not compress resulting qcow2 images. The default is to compress
366 them.
367 -v
369 --verbose
370 Enable debugging messages.
371 -V
373 --version
374 Display version number and exit.
375 -x Enable tracing of libguestfs API calls.
377
379 Unlike with "diskimage-builder", the environment of the host is not
380 inherited in the appliance when running most of the elements (i.e. all
381 except the ones in the "extra-data.d" phase).
382 To set environment for the elements being run, it is necessary to tell
384 virt-dib to use them, with the option --envvar. Such option allows to
385 selectively export environment variables when running the elements, and
386 it is the preferred way to pass environment variables to the elements.
387 To recap: if you want the environment variable "MYVAR" (and its
389 content) to be available to the elements, you can do either
390 export MYVAR # whichever is its value
392 virt-dib ... --envvar MYVAR ...
393 or
395 virt-dib ... --envvar MYVAR=value_of_it ...
397
399 Virt-dib runs most of the element in its own appliance, and thus not on
400 the host. Because of this, there is no possibility for elements to
401 cache resources directly on the host.
402 To solve this issue, virt-dib allows the usage of an helper drive where
404 to store cached resources, like disk images, distribution packages,
405 etc. While this means that there is a smaller space available for
406 caching, at least it allows to limit the space on the host for caches,
407 without assuming that elements will do that by themselves.
408 Currently this disk is either required to have a single partition on
410 it, or the first partition on it will be used. A disk with the latter
411 configuration can be easily created with guestfish(1) like the
412 following:
413 guestfish -N filename.img=fs:ext4:10G exit
415 The above will create a disk image called filename.img, 10G big, with a
417 single partition of type ext4; see "PREPARED DISK IMAGES" in
418 guestfish(1).
419 It is recommended for it to be ≥ 10G or even more, as elements will
421 cache disk images, distribution packages, etc. As with any disk image,
422 the helper disk can be easily resized using virt-resize(1) if more
423 space in it is needed.
424 The drive can be accessed like any other disk image, for example using
426 other tools of libguestfs such as guestfish(1):
427 guestfish -a filename.img -m /dev/sda1
429 If no helper drive is specified with --drive, all the resources cached
431 during a virt-dib run will be discarded.
432 RESOURCES INSIDE THE DRIVE
434 Inside the helper drive, it is possible to find the following
435 resources:
436 /home
438 This directory is set as "HOME" environment variable during the
439 build. It contains mostly the image cache (saved as
440 /home/.cache/image-create), and whichever other resource is cached
441 in the home directory of the user running the various tools.
442 /virt-dib-*.log
444 These are the logs of the elements being run within the libguestfs
445 appliance, which means all the phases except "extra-data.d".
446
448 Virt-dib can emulate also "ramdisk-image-create", which is a secondary
449 operation mode of "diskimage-builder". Instead of being a different
450 tool name, virt-dib provides easy access to this mode using the
451 --ramdisk switch.
452 In this mode:
454 · there is an additional ramdisk element added (see
456 --ramdisk-element)
457 · no image is produced (so --formats is ignored)
459 · $NAME.d (see --name) will contain initrd, kernel, etc
461
463 Virt-dib uses the standard temporary directory used by libguestfs, see
464 "ENVIRONMENT VARIABLES" in guestfs(3).
465 By default this location is /tmp (default value for "TMPDIR"), which on
467 some systems may be on a tmpfs filesystem, and thus defaulting to a
468 maximum size of half of physical RAM. If virt-dib exceeds this, it may
469 hang or exit early with an error. The solution is to point "TMPDIR" to
470 a permanent location used as temporary location, for example:
471 mkdir local-tmp
473 env TMPDIR=$PWD/local-tmp virt-dib ...
474 rm -rf local-tmp
475
477 Because of virt-dib runs most of the elements in its own appliance, all
478 the tools and libraries used by elements running outside the guest
479 (typically "root.d", "block-device.d", and "cleanup.d") need to be
480 present in the appliance as well. In case they are not, scripts will
481 fail typically with a "command not found" error.
482 For tools and libraries packaged by the distribution, the easy solution
484 is to tell libguestfs to include additional packages in the appliance.
485 This is doable by e.g. creating a new file with the additional
486 packages:
487 # echo wget > /usr/lib64/guestfs/supermin.d/dib-my-extra
489 The actual path to the supermin.d directory depends on the
491 distribution; additional files can list more packages, each in its own
492 line. For more details, see supermin(1).
493
495 Virt-dib is intended as safe replacement for "diskimage-builder" and
496 its "ramdisk-image-create" mode; the user-notable differences consist
497 in:
498 · the command line arguments; some of the arguments are the same as
500 available in "diskimage-builder", while some have different names:
501 disk-image-create virt-dib
503 ----------------- --------
504 -a ARCH --arch ARCH
505 --image-size SIZE --size SIZE
506 --max-online-resize SIZE doable using --mkfs-options
507 -n --skip-base
508 -o IMAGENAME --name IMAGENAME
509 -p PACKAGE(S) --extra-packages PACKAGE(S)
510 -t FORMAT(S) --formats FORMAT(S)
511 -x --debug 1
512 -x -x --debug 2
513 -x -x [-x ...] --debug 3/4/etc
514 · the location of non-image output files (like ramdisks and kernels)
516 · the way some of the cached resources are saved: using an helper
518 drive, not directly on the disk where virt-dib is run
519 · the need to specify a target size for the output disk, as opposed
521 to "diskimage-builder" calculating an optimal one
522 · the handling of environment variables, see "ENVIRONMENT VARIABLES".
524 Furthermore, other than the libguestfs own environment variables
526 (see "ENVIRONMENT VARIABLES" in guestfs(3)), virt-dib does not read
527 any other environment variable: this means that all the options and
528 behaviour changes are specified solely using command line arguments
529 · extra tools needed on some out-of-chroot phases need to be
531 available in the appliance, see "EXTRA DEPENDENCIES".
532 Elements themselves should notice no difference in they way they are
534 run; behaviour differences may due to wrong assumptions in elements, or
535 not correct virt-dib emulation.
536 Known issues at the moment:
538 · (none)
540
542 The --machine-readable option can be used to make the output more
543 machine friendly, which is useful when calling virt-dib from other
544 programs, GUIs etc.
545 Use the option on its own to query the capabilities of the virt-dib
547 binary. Typical output looks like this:
548 $ virt-dib --machine-readable
550 virt-dib
551 output:qcow2
552 output:tar
553 output:raw
554 output:vhd
555 A list of features is printed, one per line, and the program exits with
557 status 0.
558 The "output:" features refer to the output formats (--formats command
560 line option) supported by this binary.
561 It is possible to specify a format string for controlling the output;
563 see "ADVANCED MACHINE READABLE OUTPUT" in guestfs(3).
564
566 Virt-dib has been tested with "diskimage-builder" (and its elements) ≥
567 0.1.43; from time to time also with "tripleo-image-elements" and
568 "sahara-image-elements".
569 Previous versions may work, but it is not guaranteed.
571
573 This program returns 0 if successful, or non-zero if there was an
574 error.
575
577 guestfs(3), guestfish(1), virt-resize(1), http://libguestfs.org/.
578
580 Pino Toscano ("ptoscano at redhat dot com")
581
583 Copyright (C) 2015 Red Hat Inc.
584
586 This program is free software; you can redistribute it and/or modify it
587 under the terms of the GNU General Public License as published by the
588 Free Software Foundation; either version 2 of the License, or (at your
589 option) any later version.
590 This program is distributed in the hope that it will be useful, but
592 WITHOUT ANY WARRANTY; without even the implied warranty of
593 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
594 General Public License for more details.
595 You should have received a copy of the GNU General Public License along
597 with this program; if not, write to the Free Software Foundation, Inc.,
598 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
599
601 To get a list of bugs against libguestfs, use this link:
602 https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
603 To report a new bug against libguestfs, use this link:
605 https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
606 When reporting a bug, please supply:
608 · The version of libguestfs.
610 · Where you got libguestfs (eg. which Linux distro, compiled from
612 source, etc)
613 · Describe the bug accurately and give a way to reproduce it.
615 · Run libguestfs-test-tool(1) and paste the complete, unedited output
617 into the bug report.
618libguestfs-1.44.0 2021-01-05 virt-dib(1)