1 ganeti-os-interface(7) Ganeti | Version @GANETI_VERSION@
2 ========================================================
7 ganeti-os-interface - Specifications for guest OS types
12 The method of supporting guest operating systems in Ganeti is to have,
13 for each guest OS type, a directory containing a number of required
14 files. This directory must be present across all nodes (Ganeti doesn't
15 replicate it) in order for the OS to be usable by Ganeti.
21 There are eight required files: *create*, *import*, *export*, *rename*,
22 *verify* (executables), *ganeti_api_version*, *variants.list* and
23 *parameters.list* (text files).
28 All commands will get their input via environment variables. A
29 common set of variables will be exported for all commands, and some
30 of them might have extra ones. Note that all counts are
33 Since Ganeti version 2.5, the environment will be cleaned up before
34 being passed to scripts, therefore they will not inherit the environment
35 in with which the ganeti node daemon was started. If you depend on any
36 environment variables (non-Ganeti), then you will need to define or
37 source them appropriately.
40 The OS API version that the rest of the environment conforms to.
43 The instance name the script should operate on.
46 Both names point to the name of the instance's OS as Ganeti knows
47 it. This can simplify the OS scripts by providing the same scripts
48 under multiple names, and then the scripts can use this name to
49 alter their behaviour.
51 With OS API 15 changing the script behavior based on this variable
52 is deprecated: OS_VARIANT should be used instead (see below).
55 The variant of the OS which should be installed. Each OS must
56 support all variants listed under its variants.list file, and may
57 support more. Any more supported variants should be properly
58 documented in the per-OS documentation.
61 The hypervisor of this instance.
64 The number of disks the instance has. The actual disk defitions are
65 in a set of additional variables. The instance's disk will be
66 numbered from 0 to this value minus one.
69 The path to the storage for disk N of the instance. This might be
70 either a block device or a regular file, in which case the OS
71 scripts should use ``losetup`` (if they need to mount it). E.g. the
72 first disk of the instance might be exported as
73 ``DISK_0_PATH=/dev/drbd0``.
76 This is how the hypervisor will export the instance disks: either
77 read-write (``rw``) or read-only (``ro``).
80 The uuid associated with the N-th disk of the instance.
83 (Optional) The name, if any, associated with the N-th disk of the instance.
86 (Optional) If applicable to the current hypervisor type: the type
87 of the device exported by the hypervisor. For example, the Xen HVM
88 hypervisor can export disks as either ``paravirtual`` or
92 How files are visible on the node side. This can be either
93 ``block`` (when using block devices) or ``file:type``, where
94 ``type`` is either ``loop`` or ``blktap`` depending on how the
95 hypervisor will be configured. Note that not all backend types
96 apply to all hypervisors.
99 Similar to the ``DISK_COUNT``, this represents the number of NICs
103 The MAC address associated with this interface.
106 The uuid associated with the N-th NIC of the instance.
109 (Optional) The name, if any, associated with the N-th NIC of the instance.
112 The IP address, if any, associated with the N-th NIC of the
116 The NIC mode, routed, bridged or openvswitch
119 The bridge to which this NIC will be attached. This variable is
120 defined only when the NIC is in bridged mode.
123 In bridged or openvswitch mode, this is the interface to which the
124 NIC will be attached (same as ``NIC_%N_BRIDGE`` for bridged). In
125 routed mode it is the routing table which will be used by the
126 hypervisor to insert the appropriate routes.
129 (Optional) If applicable, the type of the exported NIC to the
130 instance, this can be one of: ``rtl8139``, ``ne2k_pci``,
131 ``ne2k_isa``, ``paravirtual``.
134 (Optional) If a NIC network is specified, the network's name.
137 (Optional) If a NIC network is specified, the network's uuid.
139 NIC_%d_NETWORK_FAMILY
140 (Optional) If a NIC network is specified, the network's family.
142 NIC_%d_NETWORK_SUBNET
143 (Optional) If a NIC network is specified, the network's IPv4 subnet.
145 NIC_%d_NETWORK_GATEWAY
146 (Optional) If a NIC network is specified, the network's IPv4
149 NIC_%d_NETWORK_SUBNET6
150 (Optional) If a NIC network is specified, the network's IPv6 subnet.
152 NIC_%d_NETWORK_GATEWAY6
153 (Optional) If a NIC network is specified, the network's IPv6
156 NIC_%d_NETWORK_MAC_PREFIX
157 (Optional) If a NIC network is specified, the network's mac prefix.
160 (Optional) If a NIC network is specified, the network's tags, space
164 Each OS parameter (see below) will be exported in its own
165 variable, prefixed with ``OSP_``, and upper-cased. For example, a
166 ``dhcp`` parameter will be exported as ``OSP_DHCP``.
169 If non-zero, this should cause the OS script to generate verbose
170 logs of its execution, for troubleshooting purposes. Currently
171 only ``0`` and ``1`` are valid values.
181 The **create** command is used for creating a new instance from
182 scratch. It has no additional environment variables bside the
185 The ``INSTANCE_NAME`` variable denotes the name of the instance,
186 which is guaranteed to resolve to an IP address. The create script
187 should configure the instance according to this name. It can
188 configure the IP statically or not, depending on the deployment
191 The ``INSTANCE_REINSTALL`` variable is set to ``1`` when this create
192 request is reinstalling an existing instance, rather than creating
193 one anew. This can be used, for example, to preserve some data in the
194 old instance in an OS-specific way.
199 This command is used in order to make a backup of a given disk of
200 the instance. The command should write to stdout a dump of the
201 given block device. The output of this program will be passed
202 during restore to the **import** command.
204 The specific disk to backup is denoted by two additional environment
205 variables: ``EXPORT_INDEX`` which denotes the index in the instance
206 disks structure (and could be used for example to skip the second disk
207 if not needed for backup) and ``EXPORT_DEVICE`` which has the same value
208 as ``DISK_N_PATH`` but is duplicated here for easier usage by shell
209 scripts (rather than parse the ``DISK_...`` variables).
211 To provide the user with an estimate on how long the export will take,
212 a predicted size can be written to the file descriptor passed in the
213 variable ``EXP_SIZE_FD``. The value is in bytes and must be terminated
214 by a newline character (``\n``). Older versions of Ganeti don't
215 support this feature, hence the variable should be checked before
218 if test -n "$EXP_SIZE_FD"; then
219 blockdev --getsize64 $blockdev >&$EXP_SIZE_FD
225 The **import** command is used for restoring an instance from a
226 backup as done by **export**. The arguments are the similar to
227 those passed to **export**, whose output will be provided on
230 The difference in variables is that the current disk is denoted by
231 ``IMPORT_DEVICE`` and ``IMPORT_INDEX`` (instead of ``EXPORT_...``).
236 This command is used in order to perform a rename at the instance
237 OS level, after the instance has been renamed in Ganeti. The
238 command should do whatever steps are required to ensure that the
239 instance is updated to use the new name, if the operating system
242 Note that it is acceptable for the rename script to do nothing at
243 all, however be warned that in this case, there will be a
244 desynchronization between what gnt-instance list shows you and the
245 actual hostname of the instance.
247 The script will be passed one additional environment variable
248 called ``OLD_INSTANCE_NAME`` which holds the old instance name. The
249 ``INSTANCE_NAME`` variable holds the new instance name.
251 A very simple rename script should at least change the hostname and
252 IP address of the instance, leaving the administrator to update the
258 The *verify* script is used to verify consistency of the OS parameters
259 (see below). The command should take one or more arguments denoting
260 what checks should be performed, and return a proper exit code
261 depending on whether the validation failed or succeeded.
263 Currently (API version 20), only one parameter is supported:
264 ``parameters``. This should validate the ``OSP_`` variables from the
265 environment, and output diagnostic messages in case the validation
268 For the ``dhcp`` parameter given as example above, a verification
279 echo "Invalid value '$OSP_DHCP' for the dhcp parameter" 1>&2
294 The ganeti_api_version file is a plain text file containing the
295 version(s) of the guest OS API that this OS definition complies
296 with, one per line. The version documented by this man page is 20,
297 so this file must contain the number 20 followed by a newline if
298 only this version is supported. A script compatible with more than
299 one Ganeti version should contain the most recent version first
300 (i.e. 20), followed by the old version(s) (in this case 15 and/or
306 variants.list is a plain text file containing all the declared supported
307 variants for this OS, one per line. If this file is missing or empty,
308 then the OS won't be considered to support variants.
310 Empty lines and lines starting with a hash (``#``) are ignored.
315 This file declares the parameters supported by the OS, one parameter
316 per line, with name and description (space and/or tab separated). For
319 dhcp Whether to enable (yes) or disable (no) dhcp
320 root_size The size of the root partition, in GiB
322 The parameters can then be used in instance add or modification, as
325 # gnt-instance add -O dhcp=no,root_size=8 ...
331 Backwards compatibility
332 ~~~~~~~~~~~~~~~~~~~~~~~
334 Ganeti 2.3 and up is compatible with API versions 10, 15 and 20. The OS
335 parameters and related scripts (verify) are only supported in
336 version 20. The variants functionality (variants.list, and OS_VARIANT
337 env. var) are supported/present only in version 15 and up.
342 All the scripts should display an usage message when called with a
343 wrong number of arguments or when the first argument is ``-h`` or
346 Upgrading from old versions
347 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
352 The ``parameters.list`` file and ``verify`` script have been
353 added. For no parameters, an empty parameters file and an empty verify
354 script which returns success can be used.
359 The ``variants.list`` file has been added, so OSes should support at
360 least one variant, declaring it in that file and must be prepared to
361 parse the OS_VARIANT environment variable. OSes are free to support more
362 variants than just the declared ones. Note that this file is optional;
363 without it, the variants functionality is disabled.
368 The method for passing data has changed from command line options
369 to environment variables, so scripts should be modified to use
370 these. For an example of how this can be done in a way compatible
371 with both versions, feel free to look at the debootstrap instance's
372 common.sh auxiliary script.
374 Also, instances can have now a variable number of disks, not only
375 two, and a variable number of NICs (instead of fixed one), so the
376 scripts should deal with this. The biggest change is in the
377 import/export, which are called once per disk, instead of once per
383 The rename script has been added. If you don't want to do any
384 changes on the instances after a rename, you can migrate the OS
385 definition to version 5 by creating the rename script simply as:
393 Note that the script must be executable.
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