X-Git-Url: https://code.grnet.gr/git/snf-image-creator/blobdiff_plain/b28209d949da5c3289c8188a7947112551594266..fab154f00c00474d8baf495cf432dc6054f1bc7e:/docs/usage.rst diff --git a/docs/usage.rst b/docs/usage.rst index 3e4acf3..c43fb29 100644 --- a/docs/usage.rst +++ b/docs/usage.rst @@ -2,9 +2,14 @@ Usage ^^^^^ snf-image-creator comes in 2 variants: + * snf-image-creator: A non-interactive command line program * snf-mkimage: A user-friendly dialog-based program +Both expect the input media as first argument. The input media may be a local +file, a block device or *"/"* if you want to create an image out of the running +system (see `host bundling operation`_). + Non-interactive version ======================= @@ -13,58 +18,60 @@ snf-image-creator receives the following options: .. code-block:: console $ snf-image-creator --help - Usage: snf-image-creator [options] Options: - --version show program's version number and exit - -h, --help show this help message and exit - -o FILE, --outfile=FILE - dump image to FILE - -f, --force overwrite output files if they exist - -s, --silent silent mode, only output errors - -u FILENAME, --upload=FILENAME - upload the image to pithos with name FILENAME - -r IMAGENAME, --register=IMAGENAME - register the image with ~okeanos as IMAGENAME - -a ACCOUNT, --account=ACCOUNT - Use this ACCOUNT when uploading/registering images - [Default: None] - -m KEY=VALUE, --metadata=KEY=VALUE - Add custom KEY=VALUE metadata to the image - -t TOKEN, --token=TOKEN - Use this token when uploading/registering images - [Default: None] - --print-sysprep print the enabled and disabled system preparation - operations for this input media - --enable-sysprep=SYSPREP - run SYSPREP operation on the input media - --disable-sysprep=SYSPREP - prevent SYSPREP operation from running on the input - media - --no-sysprep don't perform system preparation - --no-shrink don't shrink any partition - - -Most input options are self-describing. If you want to save a local copy for -the image you create, you specify *-o* option. To upload the image to -*pithos+*, you specify valid credentials with *-a* and *-t* options and a -filename using *-u*. If you want to register the image with *~okeanos*, -in addition to *-u* specify a registration name using *-r*. - -By default snf-image-creator will perform a number of system preparation -operations on the snapshot of the media and will shrink the last partition -found, before extracting the image. Both can be disabled by specifying + --version show program's version number and exit + -h, --help show this help message and exit + -o FILE, --outfile=FILE + dump image to FILE + -f, --force overwrite output files if they exist + -s, --silent output only errors + -u FILENAME, --upload=FILENAME + upload the image to pithos with name FILENAME + -r IMAGENAME, --register=IMAGENAME + register the image with ~okeanos as IMAGENAME + -m KEY=VALUE, --metadata=KEY=VALUE + add custom KEY=VALUE metadata to the image + -t TOKEN, --token=TOKEN + use this token when uploading/registering images + [Default: None] + --print-sysprep print the available enabled and disabled system + preparation operations for this input media + --enable-sysprep=SYSPREP + run SYSPREP operation on the input media + --disable-sysprep=SYSPREP + prevent SYSPREP operation from running on the input + media + --no-sysprep don't perform any system preparation operation + --no-shrink don't shrink the image + --public register image with cyclades as public + --tmpdir=DIR create large temporary image files under DIR + +Most input options are self-describing. If you want to save a local copy of +the image you create, provide a filename using the *-o* option. To upload the +image to *pithos+*, provide a valid authentication token using *-t* and a +filename using *-u*. If you also want to register the image with *~okeanos*, in +addition to *-u* provide a registration name using *-r*. All images are +registered as *private*. Only the user that registers the image can create +VM's out of it. If you want the image to be visible by other user too, use the +*--public* option. + +By default, before extracting the image, snf-image-creator will perform a +number of system preparation operations on the snapshot of the media and will +shrink the last partition found. Both actions can be disabled by specifying *--no-sysprep* and *--no-shrink* respectively. -If *--print-sysprep* is defined, the program will exit after outputing a -list of enabled and disabled system preparation operation appliable to this -media source. The user can enable or disable specific *syspreps* when creating -an image, using *-{enable,disable}-sysprep* options. You can specify those -options multiple times to enable or disable multiple *syspreps*. +If *--print-sysprep* is defined, the program will exit after printing a +list of enabled and disabled system preparation operation applicable to this +input media. The user can enable or disable specific *syspreps*, using +*-{enable,disable}-sysprep* options. The user may specify those options +multiple times. Running *snf-image-creator* with *--print-sysprep* on a raw file that hosts a -debian system, we get the following output: +debian system, we print the following output: + +.. _sysprep: .. code-block:: console @@ -124,8 +131,8 @@ debian system, we get the following output: cleaning up... -If we want the image to have all normal user accounts and all mail files -removed, we can create it specifying *--enable-sysprep* option like this: +If you want the image to have all normal user accounts and all mail files +removed, you should use *--enable-sysprep* option like this: .. code-block:: console @@ -138,18 +145,27 @@ Dialog-based version .. code-block:: console - $ Usage: snf-mkimage [options] [] + $ snf-mkimage --help + Usage: snf-mkimage [options] [] - Options: - --version show program's version number and exit - -h, --help show this help message and exit - -l FILE, --logfile=FILE - log all messages to FILE + Options: + --version show program's version number and exit + -h, --help show this help message and exit + -l FILE, --logfile=FILE + log all messages to FILE + --tmpdir=DIR create large temporary image files under DIR If the input media is not specified in the command line, in the first dialog -box the user will be asked to specify it. After the input media is examined and -the program is initialized, the user will be given the choice to run -*snf-mkimage* in *wizard* or *expert* mode. +box the user will be asked to specify it: + +.. image:: /snapshots/select_media.png + +The user can select a file (regular or block device) or use the *Bundle Host* +button to create an image out of the running system (see +`Host bundling operation`_). + +After the input media is examined and the program is initialized, the user will +be given the choice to run *snf-mkimage* in *wizard* or *expert* mode. Wizard mode ----------- @@ -158,20 +174,22 @@ When *snf-mkimage* runs in *wizard* mode, the user is just asked to provide the following basic information: * Name: A short name for the image (ex. "Slackware") - * Description: An one-line description for the image (ex. "Slackware Linux 14.0 with KDE") - * Account: An *~okeanos* account email - * Token: A token corresponding to the account defined previously + * Description: An one-line description for the image + (ex. "Slackware Linux 14.0 with KDE") + * Registration Type: Private or Public + * Account: The authentication token for an *~okeanos* account After confirming, the image will be extracted, uploaded to *pithos+* and -registered to *~okeanos*. The user will also be given the choice to keep a local -copy of it. For most users the functionality this mode provides should be -sufficient. +registered with *~okeanos*. The user will also be given the choice to keep a +local copy of it. + +For most users the functionality this mode provides should be sufficient. Expert mode ----------- Expert mode allows the user to have better control on the image creation -process. In the picture below the main menu can be seen: +process. The main menu can be seen in the picture below: .. image:: /snapshots/main_menu.png @@ -184,10 +202,166 @@ In the *Customize* sub-menu the user can control: In the *Register* sub-menu the user can provide: - * The credentials to login to *~okeanos* - * A pithos filename for the uploaded *diskdump* image - * A name for the image to be registered to *~okeanos* with + * The credentials (authentication token) to use when authenticating + to *~okeanos* + * A *pithos+* filename for the uploaded *diskdump* image + * A name for the image to use when registering it with *~okeanos*, as well as + the registration type (*private* or *public*) -By choosing the *Extract* menu entry the user can dump the image to the local -file system and finally, if the user selects *Reset*, the system will ignore +By choosing the *Extract* menu entry, the user can dump the image to the local +file system. Finally, if the user selects *Reset*, the system will ignore all changes made so far and will start the image creation process again. + +Host bundling operation +======================= + +As a new feature in *v0.2*, snf-image-creator can create images out of the host +system that runs the program. This is done either by specifying / as input +media or by using the *Bundle Host* button in the media selection dialog of +snf-mkimage. During this operation, the files of the disk are copied into a +temporary image file, which means that the file system that will host the +temporary image needs to have a lot of free space (see `large temporary files`_ +for more information). + +Creating a new image +==================== + +Suppose you want to create a new Ubuntu server image. Download the installation +disk from the Internet: + +.. code-block:: console + + $ wget http://ubuntureleases.tsl.gr/12.04.2/ubuntu-12.04.2-server-amd64.iso + +Verify that it has been downloaded correctly: + +.. code-block:: console + + $ echo 'a8c667e871f48f3a662f3fbf1c3ddb17 ubuntu-12.04.2-server-amd64.iso' > check.md5 + $ md5sum -c check.md5 + +Create a 2G sparse file to host the new system: + +.. code-block:: console + + $ truncate -s 2G ubuntu_hd.raw + +And install the Ubuntu system on this file: + +.. code-block:: console + + $ sudo kvm -boot d -drive file=ubuntu_hd.raw,format=raw,cache=none,if=virtio \ + -m 1G -cdrom ubuntu-12.04.2-server-amd64.iso + +.. warning:: + + During the installation, you will be asked about the partition scheme. Don't + use LVM partitions. They are not supported by snf-image-creator. + +You will be able to boot your installed OS and make any changes you want +(e.g. install openssh-server) using the following command:: + + $ sudo kvm -m 1G -boot c -drive file=ubuntu_hd.raw,format=raw,cache=none,if=virtio + +After you're done, you may use *snf-mkimage* as root to create and upload the +image: + +.. code-block:: console + + $ sudo -s + $ snf-mkimage ubuntu_hd.raw + +In the first screen you will be asked to choose if you want to run the program +in *Wizard* or *Expert* mode. Choose *Wizard*. + +.. image:: /snapshots/wizard.png + +Then you will be asked to provide a name, a description, a registration type +(*private* or *public*) and the authentication token corresponding to your +*~okeanos* account. Finally, you'll be asked to confirm the provided data. + +.. image:: /snapshots/confirm.png + +Choosing *YES* will create and upload the image to your *~okeanos* account. + +Limitations +=========== + +Supported operating systems +--------------------------- + +*snf-image-creator* can only fully function on input media hosting *Linux* +systems. The program will detect the needed metadata and you may use it to +upload and register other *Unix* or *Windows* images, but you cannot use it to +shrink them or perform system preparation operations. + +Logical Volumes +--------------- + +The program cannot work on LVM partitions [#f1]_. The input media may only +contain primary or logical partitions. + +Para-virtualized drivers +------------------------ + +*~Okeanos* uses the *VirtIO* framework. The disk I/O controller and the +Ethernet cards on the VM instances are para-virtualized and need special +*VirtIO* drivers. Those drivers are included in the Linux Kernel mainline since +version 2.6.25 and are shipped with all the popular Linux distributions. The +problem is that if the driver for the para-virtualized disk I/O controller is +built as module, it needs to be preloaded using an initial ramdisk, otherwise +the VM won't be able to boot. + +Many popular Linux distributions, like Ubuntu and Debian, will automatically +create a generic initial ramdisk file that contains many different modules, +including the VirtIO drivers. Others that target more experienced users, like +Slackware, won't do that [#f2]_. *snf-image-creator* cannot resolve this kind +of problems and it's left to the user to do so. Please refer to your +distribution's documentation for more information on this. You can always check +if a system can boot with para-virtualized disk controller by launching it with +kvm using the *if=virtio* option (see the kvm command in the +`Creating a new image`_ section). + +Some caveats on image creation +============================== + +Image partition schemes and shrinking +------------------------------------- + +When image shrinking is enabled, *snf-image-creator* will shrink the last +partition on the disk. If this is a swap partition, it will remove it, save +enough information to recreate it during image deployment and shrink the +partition that lays just before that. This will make the image smaller which +speeds up the deployment process. + +During image deployment, the last partition is enlarged to occupy the available +space in the VM's hard disk and a swap partition is added at the end if a SWAP +image property is present. + +Keep this in mind when creating images. It's always better to have your swap +partition placed as the last partition on the disk and have your largest +partition (*/* or */home*) just before that. + +Large temporary files +--------------------- + +*snf-image-creator* may create large temporary files when running: + + * During image shrinking, the input media snapshot file may reach the size of + the original media. + * When bundling the host system, the temporary image file may became as large + as the rest of the disk files altogether. + +*/tmp* directory is not a good place for hosting large files. In many systems +the contents of */tmp* are stored in volatile memory and the size they may occupy +is limited. By default, *snf-image-creator* will use a heuristic approach to +determine where to store large temporary files. It will examine the free space +under */var/tmp*, the user's home directory and */mnt* and will pick the one +with the most available space. The user may overwrite this behaviour and +indicate a different directory using the *tmpdir* option. This option is +supported by both *snf-image-creator* and *snf-mkimage*. + +.. rubric:: Footnotes + +.. [#f1] http://sourceware.org/lvm2/ +.. [#f2] http://mirrors.slackware.com/slackware/slackware-14.0/README.initrd