4 snf-image-creator comes in 2 variants:
6 * snf-image-creator: A non-interactive command line program
7 * snf-mkimage: A user-friendly dialog-based program
9 Both expect the input media as first argument. The input media may be a local
10 file, a block device or *"/"* if you want to create an image out of the running
11 system (see `host bundling operation`_).
13 Non-interactive version
14 =======================
16 snf-image-creator receives the following options:
18 .. code-block:: console
20 $ snf-image-creator --help
21 Usage: snf-image-creator [options] <input_media>
24 --version show program's version number and exit
25 -h, --help show this help message and exit
26 -o FILE, --outfile=FILE
28 -f, --force overwrite output files if they exist
29 -s, --silent output only errors
30 -u FILENAME, --upload=FILENAME
31 upload the image to pithos with name FILENAME
32 -r IMAGENAME, --register=IMAGENAME
33 register the image with ~okeanos as IMAGENAME
34 -a ACCOUNT, --account=ACCOUNT
35 use this ACCOUNT when uploading/registering images
37 -m KEY=VALUE, --metadata=KEY=VALUE
38 add custom KEY=VALUE metadata to the image
39 -t TOKEN, --token=TOKEN
40 use this token when uploading/registering images
42 --print-sysprep print the available enabled and disabled system
43 preparation operations for this input media
44 --enable-sysprep=SYSPREP
45 run SYSPREP operation on the input media
46 --disable-sysprep=SYSPREP
47 prevent SYSPREP operation from running on the input
49 --no-sysprep don't perform any system preparation operation
50 --no-shrink don't shrink the image
51 --tmpdir=DIR create large temporary image files under DIR
53 Most input options are self-describing. If you want to save a local copy of
54 the image you create, provide a filename using the *-o* option. To upload the
55 image to *pithos+*, provide valid credentials using *-a* and *-t* and a
56 filename using *-u*. If you also want to register the image with *~okeanos*, in
57 addition to *-u* provide a registration name using *-r*.
59 By default, before extracting the image, snf-image-creator will perform a
60 number of system preparation operations on the snapshot of the media and will
61 shrink the last partition found. Both actions can be disabled by specifying
62 *--no-sysprep* and *--no-shrink* respectively.
64 If *--print-sysprep* is defined, the program will exit after printing a
65 list of enabled and disabled system preparation operation applicable to this
66 input media. The user can enable or disable specific *syspreps*, using
67 *-{enable,disable}-sysprep* options. The user may specify those options
70 Running *snf-image-creator* with *--print-sysprep* on a raw file that hosts a
71 debian system, we print the following output:
75 .. code-block:: console
77 $ snf-image-creator --print-sysprep debian_desktop.img
81 Examining source media `debian_desktop.img'... looks like an image file
82 Snapshotting media source... done
83 Enabling recovery proc
84 Launching helper VM... done
85 Inspecting Operating System... found a(n) debian system
86 Mounting the media read-only... done
88 Enabled system preparation operations:
90 Remove all regular files under /var/cache
93 Empty all files under /var/log
96 Remove all passwords and lock all user accounts
99 Remove all files under /tmp and /var/tmp
102 Delete sensitive userdata
105 Replace acpid powerdown action scripts to immediately shutdown the
106 system without checking if a GUI is running.
108 remove-persistent-net-rules:
109 Remove udev rules that will keep network interface names persistent
110 after hardware changes and reboots. Those rules will be created again
111 the next time the image runs.
114 Remove swap entry from /etc/fstab. If swap is the last partition
115 then the partition will be removed when shrinking is performed. If the
116 swap partition is not the last partition in the disk or if you are not
117 going to shrink the image you should probably disable this.
119 use-persistent-block-device-names:
120 Scan fstab & grub configuration files and replace all non-persistent
121 device references with UUIDs.
123 Disabled system preparation operations:
125 Remove all files under /var/mail and /var/spool/mail
127 remove-user-accounts:
128 Remove all user accounts with id greater than 1000
133 If you want the image to have all normal user accounts and all mail files
134 removed, you should use *--enable-sysprep* option like this:
136 .. code-block:: console
138 $ snf-image-creator --enable-sysprep cleanup-mail --enable-sysprep remove-user-accounts ...
143 *snf-mkimage* receives the following options:
145 .. code-block:: console
148 Usage: snf-mkimage [options] [<input_media>]
151 --version show program's version number and exit
152 -h, --help show this help message and exit
153 -l FILE, --logfile=FILE
154 log all messages to FILE
155 --tmpdir=DIR create large temporary image files under DIR
157 If the input media is not specified in the command line, in the first dialog
158 box the user will be asked to specify it:
160 .. image:: /snapshots/select_media.png
162 The user can select a file (regular or block device) or use the *Bundle Host*
163 button to create an image out of the running system (see
164 `Host bundling operation`_).
166 After the input media is examined and the program is initialized, the user will
167 be given the choice to run *snf-mkimage* in *wizard* or *expert* mode.
172 When *snf-mkimage* runs in *wizard* mode, the user is just asked to provide the
173 following basic information:
175 * Name: A short name for the image (ex. "Slackware")
176 * Description: An one-line description for the image
177 (ex. "Slackware Linux 14.0 with KDE")
178 * Account: An *~okeanos* account email
179 * Token: A token corresponding to the account given above
181 After confirming, the image will be extracted, uploaded to *pithos+* and
182 registered with *~okeanos*. The user will also be given the choice to keep a
185 For most users the functionality this mode provides should be sufficient.
190 Expert mode allows the user to have better control on the image creation
191 process. The main menu can be seen in the picture below:
193 .. image:: /snapshots/main_menu.png
195 In the *Customize* sub-menu the user can control:
197 * The system preparation operations that will be applied on the media
198 * Whether the image will be shrunk or not
199 * The properties associated with the image
200 * The configuration tasks that will run during image deployment
202 In the *Register* sub-menu the user can provide:
204 * The credentials to login to *~okeanos*
205 * A *pithos+* filename for the uploaded *diskdump* image
206 * A name for the image to be registered to *~okeanos* with
208 By choosing the *Extract* menu entry, the user can dump the image to the local
209 file system. Finally, if the user selects *Reset*, the system will ignore
210 all changes made so far and will start the image creation process again.
212 Host bundling operation
213 =======================
215 As a new feature in *v0.2*, snf-image-creator can create images out of the host
216 system that runs the program. This is done either by specifying / as input
217 media or by using the *Bundle Host* button in the media selection dialog of
218 snf-mkimage. During this operation, the files of the disk are copied into a
219 temporary image file, which means that the file system that will host the
220 temporary image needs to have a lot of free space (see `large temporary files`_
221 for more information).
226 Suppose you want to create a new Ubuntu server image. Download the installation
227 disk from the Internet:
229 .. code-block:: console
231 $ wget http://ubuntureleases.tsl.gr/12.04.1/ubuntu-12.04.1-server-amd64.iso
233 Verify that it has been downloaded correctly:
235 .. code-block:: console
237 $ echo 'a8c667e871f48f3a662f3fbf1c3ddb17 ubuntu-12.04.1-server-amd64.iso' > check.md5
238 $ md5sum -c check.md5
240 Create a 2G sparse file to host the new system:
242 .. code-block:: console
244 $ truncate -s 2G ubuntu_hd.raw
246 And install the Ubuntu system on this file:
248 .. code-block:: console
250 $ sudo kvm -boot d -drive file=ubuntu_hd.raw,format=raw,cache=none,if=virtio \
251 -m 1G -cdrom ubuntu-12.04.1-server-amd64.iso
255 During the installation, you will be asked about the partition scheme. Don't
256 use LVM partitions. They are not supported by snf-image-creator.
258 You will be able to boot your installed OS and make any changes you want
259 (e.g. install openssh-server) using the following command::
261 $ sudo kvm -m 1G -boot c -drive file=ubuntu_hd.raw,format=raw,cache=none,if=virtio
263 After you're done, you may use *snf-mkimage* as root to create and upload the
266 .. code-block:: console
269 $ snf-mkimage ubuntu_hd.raw
271 In the first screen you will be asked to choose if you want to run the program
272 in *Wizard* or *Expert* mode. Choose *Wizard*.
274 .. image:: /snapshots/01_wizard.png
276 Then you will be asked to provide a name, a description, an *~okeanos* account
277 and the token corresponding to this account. Finally, you'll be asked to
278 confirm the provided data.
280 .. image:: /snapshots/06_confirm.png
282 Choosing *YES* will create and upload the image to your *~okeanos* account.
287 Supported operating systems
288 ---------------------------
290 *snf-image-creator* can only fully function on input media hosting *Linux*
291 systems. The program will detect the needed metadata and you may use it to
292 upload and register other *Unix* or *Windows* images, but you cannot use it to
293 shrink them or perform system preparation operations.
298 The program cannot work on LVM partitions [#f1]_. The input media may only
299 contain primary or logical partitions.
301 Para-virtualized drivers
302 ------------------------
304 *~Okeanos* uses the *VirtIO* framework. The disk I/O controller and the
305 Ethernet cards on the VM instances are para-virtualized and need special
306 *VirtIO* drivers. Those drivers are included in the Linux Kernel mainline since
307 version 2.6.25 and are shipped with all the popular Linux distributions. The
308 problem is that if the driver for the para-virtualized disk I/O controller is
309 built as module, it needs to be preloaded using an initial ramdisk, otherwise
310 the VM won't be able to boot.
312 Many popular Linux distributions, like Ubuntu and Debian, will automatically
313 create a generic initial ramdisk file that contains many different modules,
314 including the VirtIO drivers. Others that target more experienced users, like
315 Slackware, won't do that [#f2]_. *snf-image-creator* cannot resolve this kind
316 of problems and it's left to the user to do so. Please refer to your
317 distribution's documentation for more information on this. You can always check
318 if a system can boot with para-virtualized disk controller by launching it with
319 kvm using the *if=virtio* option (see the kvm command in the
320 `Creating a new image`_ section).
322 Some caveats on image creation
323 ==============================
325 Image partition schemes and shrinking
326 -------------------------------------
328 When image shrinking is enabled, *snf-image-creator* will shrink the last
329 partition on the disk. If this is a swap partition, it will remove it, save
330 enough information to recreate it during image deployment and shrink the
331 partition that lays just before that. This will make the image smaller which
332 speeds up the deployment process.
334 During image deployment, the last partition is enlarged to occupy the available
335 space in the VM's hard disk and a swap partition is added at the end if a SWAP
336 image property is present.
338 Keep this in mind when creating images. It's always better to have your swap
339 partition placed as the last partition on the disk and have your largest
340 partition (*/* or */home*) just before that.
342 Large temporary files
343 ---------------------
345 *snf-image-creator* may create large temporary files when running:
347 * During image shrinking, the input media snapshot file may reach the size of
349 * When bundling the host system, the temporary image file may became as large
350 as the rest of the disk files altogether.
352 */tmp* directory is not a good place for hosting large files. In many systems
353 the contents of */tmp* are stored in volatile memory and the size they may occupy
354 is limited. By default, *snf-image-creator* will use a heuristic approach to
355 determine where to store large temporary files. It will examine the free space
356 under */var/tmp*, the user's home directory and */mnt* and will pick the one
357 with the most available space. The user may overwrite this behaviour and
358 indicate a different directory using the *tmpdir* option. This option is
359 supported by both *snf-image-creator* and *snf-mkimage*.
361 .. rubric:: Footnotes
363 .. [#f1] http://sourceware.org/lvm2/
364 .. [#f2] http://mirrors.slackware.com/slackware/slackware-14.0/README.initrd