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10.8.25 Virtualization Services

The (gnu services virtualization) module provides services for the libvirt and virtlog daemons, as well as other virtualization-related services.

Libvirt daemon

libvirtd is the server side daemon component of the libvirt virtualization management system. This daemon runs on host servers and performs required management tasks for virtualized guests.

Scheme Variable: libvirt-service-type

This is the type of the libvirt daemon. Its value must be a libvirt-configuration.

(service libvirt-service-type
         (libvirt-configuration
          (unix-sock-group "libvirt")
          (tls-port "16555")))

Available libvirt-configuration fields are:

libvirt-configuration parameter: package libvirt

Libvirt package.

libvirt-configuration parameter: boolean listen-tls?

Flag listening for secure TLS connections on the public TCP/IP port. You must set listen for this to have any effect.

It is necessary to setup a CA and issue server certificates before using this capability.

Defaults to ‘#t’.

libvirt-configuration parameter: boolean listen-tcp?

Listen for unencrypted TCP connections on the public TCP/IP port. You must set listen for this to have any effect.

Using the TCP socket requires SASL authentication by default. Only SASL mechanisms which support data encryption are allowed. This is DIGEST_MD5 and GSSAPI (Kerberos5).

Defaults to ‘#f’.

libvirt-configuration parameter: string tls-port

Port for accepting secure TLS connections. This can be a port number, or service name.

Defaults to ‘"16514"’.

libvirt-configuration parameter: string tcp-port

Port for accepting insecure TCP connections. This can be a port number, or service name.

Defaults to ‘"16509"’.

libvirt-configuration parameter: string listen-addr

IP address or hostname used for client connections.

Defaults to ‘"0.0.0.0"’.

libvirt-configuration parameter: boolean mdns-adv?

Flag toggling mDNS advertisement of the libvirt service.

Alternatively can disable for all services on a host by stopping the Avahi daemon.

Defaults to ‘#f’.

libvirt-configuration parameter: string mdns-name

Default mDNS advertisement name. This must be unique on the immediate broadcast network.

Defaults to ‘"Virtualization Host <hostname>"’.

libvirt-configuration parameter: string unix-sock-group

UNIX domain socket group ownership. This can be used to allow a ’trusted’ set of users access to management capabilities without becoming root.

Defaults to ‘"root"’.

libvirt-configuration parameter: string unix-sock-ro-perms

UNIX socket permissions for the R/O socket. This is used for monitoring VM status only.

Defaults to ‘"0777"’.

libvirt-configuration parameter: string unix-sock-rw-perms

UNIX socket permissions for the R/W socket. Default allows only root. If PolicyKit is enabled on the socket, the default will change to allow everyone (eg, 0777)

Defaults to ‘"0770"’.

libvirt-configuration parameter: string unix-sock-admin-perms

UNIX socket permissions for the admin socket. Default allows only owner (root), do not change it unless you are sure to whom you are exposing the access to.

Defaults to ‘"0777"’.

libvirt-configuration parameter: string unix-sock-dir

The directory in which sockets will be found/created.

Defaults to ‘"/var/run/libvirt"’.

libvirt-configuration parameter: string auth-unix-ro

Authentication scheme for UNIX read-only sockets. By default socket permissions allow anyone to connect

Defaults to ‘"polkit"’.

libvirt-configuration parameter: string auth-unix-rw

Authentication scheme for UNIX read-write sockets. By default socket permissions only allow root. If PolicyKit support was compiled into libvirt, the default will be to use ’polkit’ auth.

Defaults to ‘"polkit"’.

libvirt-configuration parameter: string auth-tcp

Authentication scheme for TCP sockets. If you don’t enable SASL, then all TCP traffic is cleartext. Don’t do this outside of a dev/test scenario.

Defaults to ‘"sasl"’.

libvirt-configuration parameter: string auth-tls

Authentication scheme for TLS sockets. TLS sockets already have encryption provided by the TLS layer, and limited authentication is done by certificates.

It is possible to make use of any SASL authentication mechanism as well, by using ’sasl’ for this option

Defaults to ‘"none"’.

libvirt-configuration parameter: optional-list access-drivers

API access control scheme.

By default an authenticated user is allowed access to all APIs. Access drivers can place restrictions on this.

Defaults to ‘()’.

libvirt-configuration parameter: string key-file

Server key file path. If set to an empty string, then no private key is loaded.

Defaults to ‘""’.

libvirt-configuration parameter: string cert-file

Server key file path. If set to an empty string, then no certificate is loaded.

Defaults to ‘""’.

libvirt-configuration parameter: string ca-file

Server key file path. If set to an empty string, then no CA certificate is loaded.

Defaults to ‘""’.

libvirt-configuration parameter: string crl-file

Certificate revocation list path. If set to an empty string, then no CRL is loaded.

Defaults to ‘""’.

libvirt-configuration parameter: boolean tls-no-sanity-cert

Disable verification of our own server certificates.

When libvirtd starts it performs some sanity checks against its own certificates.

Defaults to ‘#f’.

libvirt-configuration parameter: boolean tls-no-verify-cert

Disable verification of client certificates.

Client certificate verification is the primary authentication mechanism. Any client which does not present a certificate signed by the CA will be rejected.

Defaults to ‘#f’.

libvirt-configuration parameter: optional-list tls-allowed-dn-list

Whitelist of allowed x509 Distinguished Name.

Defaults to ‘()’.

libvirt-configuration parameter: optional-list sasl-allowed-usernames

Whitelist of allowed SASL usernames. The format for username depends on the SASL authentication mechanism.

Defaults to ‘()’.

libvirt-configuration parameter: string tls-priority

Override the compile time default TLS priority string. The default is usually ‘"NORMAL"’ unless overridden at build time. Only set this is it is desired for libvirt to deviate from the global default settings.

Defaults to ‘"NORMAL"’.

libvirt-configuration parameter: integer max-clients

Maximum number of concurrent client connections to allow over all sockets combined.

Defaults to ‘5000’.

libvirt-configuration parameter: integer max-queued-clients

Maximum length of queue of connections waiting to be accepted by the daemon. Note, that some protocols supporting retransmission may obey this so that a later reattempt at connection succeeds.

Defaults to ‘1000’.

libvirt-configuration parameter: integer max-anonymous-clients

Maximum length of queue of accepted but not yet authenticated clients. Set this to zero to turn this feature off

Defaults to ‘20’.

libvirt-configuration parameter: integer min-workers

Number of workers to start up initially.

Defaults to ‘5’.

libvirt-configuration parameter: integer max-workers

Maximum number of worker threads.

If the number of active clients exceeds min-workers, then more threads are spawned, up to max_workers limit. Typically you’d want max_workers to equal maximum number of clients allowed.

Defaults to ‘20’.

libvirt-configuration parameter: integer prio-workers

Number of priority workers. If all workers from above pool are stuck, some calls marked as high priority (notably domainDestroy) can be executed in this pool.

Defaults to ‘5’.

libvirt-configuration parameter: integer max-requests

Total global limit on concurrent RPC calls.

Defaults to ‘20’.

libvirt-configuration parameter: integer max-client-requests

Limit on concurrent requests from a single client connection. To avoid one client monopolizing the server this should be a small fraction of the global max_requests and max_workers parameter.

Defaults to ‘5’.

libvirt-configuration parameter: integer admin-min-workers

Same as min-workers but for the admin interface.

Defaults to ‘1’.

libvirt-configuration parameter: integer admin-max-workers

Same as max-workers but for the admin interface.

Defaults to ‘5’.

libvirt-configuration parameter: integer admin-max-clients

Same as max-clients but for the admin interface.

Defaults to ‘5’.

libvirt-configuration parameter: integer admin-max-queued-clients

Same as max-queued-clients but for the admin interface.

Defaults to ‘5’.

libvirt-configuration parameter: integer admin-max-client-requests

Same as max-client-requests but for the admin interface.

Defaults to ‘5’.

libvirt-configuration parameter: integer log-level

Logging level. 4 errors, 3 warnings, 2 information, 1 debug.

Defaults to ‘3’.

libvirt-configuration parameter: string log-filters

Logging filters.

A filter allows to select a different logging level for a given category of logs. The format for a filter is one of:

where name is a string which is matched against the category given in the VIR_LOG_INIT() at the top of each libvirt source file, e.g., ‘"remote"’, ‘"qemu"’, or ‘"util.json"’ (the name in the filter can be a substring of the full category name, in order to match multiple similar categories), the optional ‘"+"’ prefix tells libvirt to log stack trace for each message matching name, and x is the minimal level where matching messages should be logged:

Multiple filters can be defined in a single filters statement, they just need to be separated by spaces.

Defaults to ‘"3:remote 4:event"’.

libvirt-configuration parameter: string log-outputs

Logging outputs.

An output is one of the places to save logging information. The format for an output can be:

x:stderr

output goes to stderr

x:syslog:name

use syslog for the output and use the given name as the ident

x:file:file_path

output to a file, with the given filepath

x:journald

output to journald logging system

In all case the x prefix is the minimal level, acting as a filter

Multiple outputs can be defined, they just need to be separated by spaces.

Defaults to ‘"3:stderr"’.

libvirt-configuration parameter: integer audit-level

Allows usage of the auditing subsystem to be altered

Defaults to ‘1’.

libvirt-configuration parameter: boolean audit-logging

Send audit messages via libvirt logging infrastructure.

Defaults to ‘#f’.

libvirt-configuration parameter: optional-string host-uuid

Host UUID. UUID must not have all digits be the same.

Defaults to ‘""’.

libvirt-configuration parameter: string host-uuid-source

Source to read host UUID.

If dmidecode does not provide a valid UUID a temporary UUID will be generated.

Defaults to ‘"smbios"’.

libvirt-configuration parameter: integer keepalive-interval

A keepalive message is sent to a client after keepalive_interval seconds of inactivity to check if the client is still responding. If set to -1, libvirtd will never send keepalive requests; however clients can still send them and the daemon will send responses.

Defaults to ‘5’.

libvirt-configuration parameter: integer keepalive-count

Maximum number of keepalive messages that are allowed to be sent to the client without getting any response before the connection is considered broken.

In other words, the connection is automatically closed approximately after keepalive_interval * (keepalive_count + 1) seconds since the last message received from the client. When keepalive-count is set to 0, connections will be automatically closed after keepalive-interval seconds of inactivity without sending any keepalive messages.

Defaults to ‘5’.

libvirt-configuration parameter: integer admin-keepalive-interval

Same as above but for admin interface.

Defaults to ‘5’.

libvirt-configuration parameter: integer admin-keepalive-count

Same as above but for admin interface.

Defaults to ‘5’.

libvirt-configuration parameter: integer ovs-timeout

Timeout for Open vSwitch calls.

The ovs-vsctl utility is used for the configuration and its timeout option is set by default to 5 seconds to avoid potential infinite waits blocking libvirt.

Defaults to ‘5’.

Virtlog daemon

The virtlogd service is a server side daemon component of libvirt that is used to manage logs from virtual machine consoles.

This daemon is not used directly by libvirt client applications, rather it is called on their behalf by libvirtd. By maintaining the logs in a standalone daemon, the main libvirtd daemon can be restarted without risk of losing logs. The virtlogd daemon has the ability to re-exec() itself upon receiving SIGUSR1, to allow live upgrades without downtime.

Scheme Variable: virtlog-service-type

This is the type of the virtlog daemon. Its value must be a virtlog-configuration.

(service virtlog-service-type
         (virtlog-configuration
          (max-clients 1000)))
virtlog-configuration parameter: integer log-level

Logging level. 4 errors, 3 warnings, 2 information, 1 debug.

Defaults to ‘3’.

virtlog-configuration parameter: string log-filters

Logging filters.

A filter allows to select a different logging level for a given category of logs The format for a filter is one of:

where name is a string which is matched against the category given in the VIR_LOG_INIT() at the top of each libvirt source file, e.g., "remote", "qemu", or "util.json" (the name in the filter can be a substring of the full category name, in order to match multiple similar categories), the optional "+" prefix tells libvirt to log stack trace for each message matching name, and x is the minimal level where matching messages should be logged:

Multiple filters can be defined in a single filters statement, they just need to be separated by spaces.

Defaults to ‘"3:remote 4:event"’.

virtlog-configuration parameter: string log-outputs

Logging outputs.

An output is one of the places to save logging information The format for an output can be:

x:stderr

output goes to stderr

x:syslog:name

use syslog for the output and use the given name as the ident

x:file:file_path

output to a file, with the given filepath

x:journald

output to journald logging system

In all case the x prefix is the minimal level, acting as a filter

Multiple outputs can be defined, they just need to be separated by spaces.

Defaults to ‘"3:stderr"’.

virtlog-configuration parameter: integer max-clients

Maximum number of concurrent client connections to allow over all sockets combined.

Defaults to ‘1024’.

virtlog-configuration parameter: integer max-size

Maximum file size before rolling over.

Defaults to ‘2MB

virtlog-configuration parameter: integer max-backups

Maximum number of backup files to keep.

Defaults to ‘3

Transparent Emulation with QEMU

qemu-binfmt-service-type provides support for transparent emulation of program binaries built for different architectures—e.g., it allows you to transparently execute an ARMv7 program on an x86_64 machine. It achieves this by combining the QEMU emulator and the binfmt_misc feature of the kernel Linux. This feature only allows you to emulate GNU/Linux on a different architecture, but see below for GNU/Hurd support.

Scheme Variable: qemu-binfmt-service-type

This is the type of the QEMU/binfmt service for transparent emulation. Its value must be a qemu-binfmt-configuration object, which specifies the QEMU package to use as well as the architecture we want to emulated:

In this example, we enable transparent emulation for the ARM and aarch64 platforms. Running herd stop qemu-binfmt turns it off, and running herd start qemu-binfmt turns it back on (see the herd command in The GNU Shepherd Manual).

Data Type: qemu-binfmt-configuration

This is the configuration for the qemu-binfmt service.

platforms (default: '())

The list of emulated QEMU platforms. Each item must be a platform object as returned by lookup-qemu-platforms (see below).

guix-support? (default: #f)

When it is true, QEMU and all its dependencies are added to the build environment of guix-daemon (see --chroot-directory option). This allows the binfmt_misc handlers to be used within the build environment, which in turn means that you can transparently build programs for another architecture.

For example, let’s suppose you’re on an x86_64 machine and you have this service:

You can run:

guix build -s armhf-linux inkscape

and it will build Inkscape for ARMv7 as if it were a native build, transparently using QEMU to emulate the ARMv7 CPU. Pretty handy if you’d like to test a package build for an architecture you don’t have access to!

qemu (default: qemu)

The QEMU package to use.

Scheme Procedure: lookup-qemu-platforms platforms

Return the list of QEMU platform objects corresponding to platforms…. platforms must be a list of strings corresponding to platform names, such as "arm", "sparc", "mips64el", and so on.

Scheme Procedure: qemu-platform? obj

Return true if obj is a platform object.

Scheme Procedure: qemu-platform-name platform

Return the name of platform—a string such as "arm".

The Hurd in a Virtual Machine

Service hurd-vm provides support for running GNU/Hurd in a virtual machine (VM), a so-called childhurd. This service is meant to be used on GNU/Linux and the given GNU/Hurd operating system configuration is cross-compiled. The virtual machine is a Shepherd service that can be referred to by the names hurd-vm and childhurd and be controlled with commands such as:

herd start hurd-vm
herd stop childhurd

When the service is running, you can view its console by connecting to it with a VNC client, for example with:

guix environment --ad-hoc tigervnc-client -- \
         vncviewer localhost:5900

The default configuration (see hurd-vm-configuration below) spawns a secure shell (SSH) server in your GNU/Hurd system, which QEMU (the virtual machine emulator) redirects to port 10222 on the host. Thus, you can connect over SSH to the childhurd with:

ssh root@localhost -p 10022

The childhurd is volatile and stateless: it starts with a fresh root file system every time you restart it. By default though, all the files under /etc/childhurd on the host are copied as is to the root file system of the childhurd when it boots. This allows you to initialize “secrets” inside the VM: SSH host keys, authorized substitute keys, and so on—see the explanation of secret-root below.

Scheme Variable: hurd-vm-service-type

This is the type of the Hurd in a Virtual Machine service. Its value must be a hurd-vm-configuration object, which specifies the operating system (see operating-system Reference) and the disk size for the Hurd Virtual Machine, the QEMU package to use as well as the options for running it.

For example:

(service hurd-vm-service-type
         (hurd-vm-configuration
          (disk-size (* 5000 (expt 2 20))) ;5G
          (memory-size 1024)))             ;1024MiB

would create a disk image big enough to build GNU Hello, with some extra memory.

Data Type: hurd-vm-configuration

The data type representing the configuration for hurd-vm-service-type.

os (default: %hurd-vm-operating-system)

The operating system to instantiate. This default is bare-bones with a permissive OpenSSH secure shell daemon listening on port 2222 (see openssh-service-type).

qemu (default: qemu-minimal)

The QEMU package to use.

image (default: hurd-vm-disk-image)

The procedure used to build the disk-image built from this configuration.

disk-size (default: 'guess)

The size of the disk image.

memory-size (default: 512)

The memory size of the Virtual Machine in mebibytes.

options (default: '("--snapshot"))

The extra options for running QEMU.

id (default: #f)

If set, a non-zero positive integer used to parameterize Childhurd instances. It is appended to the service’s name, e.g. childhurd1.

net-options (default: hurd-vm-net-options)

The procedure used to produce the list of QEMU networking options.

By default, it produces

'("--device" "rtl8139,netdev=net0"
  "--netdev" "user,id=net0\
              ,hostfwd=tcp:127.0.0.1:secrets-port-:1004\
              ,hostfwd=tcp:127.0.0.1:ssh-port-:2222\
              ,hostfwd=tcp:127.0.0.1:vnc-port-:5900")

with forwarded ports:

secrets-port: (+ 11004 (* 1000 ID))
ssh-port: (+ 10022 (* 1000 ID))
vnc-port: (+ 15900 (* 1000 ID))
secret-root (default: /etc/childhurd)

The root directory with out-of-band secrets to be installed into the childhurd once it runs. Childhurds are volatile which means that on every startup, secrets such as the SSH host keys and Guix signing key are recreated.

If the /etc/childhurd directory does not exist, the secret-service running in the Childhurd will be sent an empty list of secrets.

By default, the service automatically populates /etc/childhurd with the following non-volatile secrets, unless they already exist:

/etc/childhurd/etc/guix/acl
/etc/childhurd/etc/guix/signing-key.pub
/etc/childhurd/etc/guix/signing-key.sec
/etc/childhurd/etc/ssh/ssh_host_ed25519_key
/etc/childhurd/etc/ssh/ssh_host_ecdsa_key
/etc/childhurd/etc/ssh/ssh_host_ed25519_key.pub
/etc/childhurd/etc/ssh/ssh_host_ecdsa_key.pub

These files are automatically sent to the guest Hurd VM when it boots, including permissions.

Having these files in place means that only a couple of things are missing to allow the host to offload i586-gnu builds to the childhurd:

  1. Authorizing the childhurd’s key on the host so that the host accepts build results coming from the childhurd, which can be done like so:
    guix archive --authorize < \
      /etc/childhurd/etc/guix/signing-key.pub
    
  2. Adding the childhurd to /etc/guix/machines.scm (see Daemon Offload Setup).

We’re working towards making that happen automatically—get in touch with us at guix-devel@gnu.org to discuss it!

Note that by default the VM image is volatile, i.e., once stopped the contents are lost. If you want a stateful image instead, override the configuration’s image and options without the --snapshot flag using something along these lines:

(service hurd-vm-service-type
         (hurd-vm-configuration
          (image   (const "/out/of/store/writable/hurd.img"))
          (options '())))

Ganeti

Note: This service is considered experimental. Configuration options may be changed in a backwards-incompatible manner, and not all features have been thorougly tested. Users of this service are encouraged to share their experience at guix-devel@gnu.org.

Ganeti is a virtual machine management system. It is designed to keep virtual machines running on a cluster of servers even in the event of hardware failures, and to make maintenance and recovery tasks easy. It consists of multiple services which are described later in this section. In addition to the Ganeti service, you will need the OpenSSH service (see openssh-service-type), and update the /etc/hosts file (see hosts-file) with the cluster name and address (or use a DNS server).

All nodes participating in a Ganeti cluster should have the same Ganeti and /etc/hosts configuration. Here is an example configuration for a Ganeti cluster node that supports multiple storage backends, and installs the debootstrap and guix OS providers:

(use-package-modules virtualization)
(use-service-modules base ganeti networking ssh)
(operating-system
  ;; …
  (host-name "node1")
  (hosts-file (plain-file "hosts" (format #f "
127.0.0.1       localhost
::1             localhost

192.168.1.200   ganeti.example.com
192.168.1.201   node1.example.com node1
192.168.1.202   node2.example.com node2
")))

  ;; Install QEMU so we can use KVM-based instances, and LVM, DRBD and Ceph
  ;; in order to use the "plain", "drbd" and "rbd" storage backends.
  (packages (append (map specification->package
                         '("qemu" "lvm2" "drbd-utils" "ceph"
                           ;; Add the debootstrap and guix OS providers.
                           "ganeti-instance-guix" "ganeti-instance-debootstrap"))
                    %base-packages))
  (services
   (append (list (static-networking-service "eth0" "192.168.1.201"
                                            #:netmask "255.255.255.0"
                                            #:gateway "192.168.1.254"
                                            #:name-servers '("192.168.1.252"
                                                             "192.168.1.253"))

                 ;; Ganeti uses SSH to communicate between nodes.
                 (service openssh-service-type
                          (openssh-configuration
                           (permit-root-login 'without-password)))

                 (service ganeti-service-type
                          (ganeti-configuration
                           ;; This list specifies allowed file system paths
                           ;; for storing virtual machine images.
                           (file-storage-paths '("/srv/ganeti/file-storage"))
                           ;; This variable configures a single "variant" for
                           ;; both Debootstrap and Guix that works with KVM.
                           (os %default-ganeti-os))))
           %base-services)))

Users are advised to read the Ganeti administrators guide to learn about the various cluster options and day-to-day operations. There is also a blog post describing how to configure and initialize a small cluster.

Scheme Variable: ganeti-service-type

This is a service type that includes all the various services that Ganeti nodes should run.

Its value is a ganeti-configuration object that defines the package to use for CLI operations, as well as configuration for the various daemons. Allowed file storage paths and available guest operating systems are also configured through this data type.

Data Type: ganeti-configuration

The ganeti service takes the following configuration options:

ganeti (default: ganeti)

The ganeti package to use. It will be installed to the system profile and make gnt-cluster, gnt-instance, etc available. Note that the value specified here does not affect the other services as each refer to a specific ganeti package (see below).

noded-configuration (default: (ganeti-noded-configuration))
confd-configuration (default: (ganeti-confd-configuration))
wconfd-configuration (default: (ganeti-wconfd-configuration))
luxid-configuration (default: (ganeti-luxid-configuration))
rapi-configuration (default: (ganeti-rapi-configuration))
kvmd-configuration (default: (ganeti-kvmd-configuration))
mond-configuration (default: (ganeti-mond-configuration))
metad-configuration (default: (ganeti-metad-configuration))
watcher-configuration (default: (ganeti-watcher-configuration))
cleaner-configuration (default: (ganeti-cleaner-configuration))

These options control the various daemons and cron jobs that are distributed with Ganeti. The possible values for these are described in detail below. To override a setting, you must use the configuration type for that service:

(service ganeti-service-type
         (ganeti-configuration
          (rapi-configuration
           (ganeti-rapi-configuration
            (interface "eth1"))))
          (watcher-configuration
           (ganeti-watcher-configuration
            (rapi-ip "10.0.0.1"))))
file-storage-paths (default: '())

List of allowed directories for file storage backend.

os (default: %default-ganeti-os)

List of <ganeti-os> records.

In essence ganeti-service-type is shorthand for declaring each service individually:

Plus a service extension for etc-service-type that configures the file storage backend and OS variants.

Data Type: ganeti-os

This data type is suitable for passing to the os parameter of ganeti-configuration. It takes the following parameters:

name

The name for this OS provider. It is only used to specify where the configuration ends up. Setting it to “debootstrap” will create /etc/ganeti/instance-debootstrap.

extension

The file extension for variants of this OS type. For example .conf or .scm.

variants (default: '())

List of ganeti-os-variant objects for this OS.

Data Type: ganeti-os-variant

This is the data type for a Ganeti OS variant. It takes the following parameters:

name

The name of this variant.

configuration

A configuration file for this variant.

Scheme Variable: %default-debootstrap-hooks

This variable contains hooks to configure networking and the GRUB bootloader.

Scheme Variable: %default-debootstrap-extra-pkgs

This variable contains a list of packages suitable for a fully-virtualized guest.

Data Type: debootstrap-configuration

This data type creates configuration files suitable for the debootstrap OS provider.

hooks (default: %default-debootstrap-hooks)

When not #f, this must be a G-expression that specifies a directory with scripts that will run when the OS is installed. It can also be a list of (name . file-like) pairs. For example:

`((99-hello-world . ,(plain-file "#!/bin/sh\necho Hello, World")))

That will create a directory with one executable named 99-hello-world and run it every time this variant is installed. If set to #f, hooks in /etc/ganeti/instance-debootstrap/hooks will be used, if any.

proxy (default: #f)

Optional HTTP proxy to use.

mirror (default: #f)

The Debian mirror. Typically something like http://ftp.no.debian.org/debian. The default varies depending on the distribution.

arch (default: #f)

The dpkg architecture. Set to armhf to debootstrap an ARMv7 instance on an AArch64 host. Default is to use the current system architecture.

suite (default: "stable")

When set, this must be a Debian distribution “suite” such as buster or focal. If set to #f, the default for the OS provider is used.

extra-pkgs (default: %default-debootstrap-extra-pkgs)

List of extra packages that will get installed by dpkg in addition to the minimal system.

components (default: #f)

When set, must be a list of Debian repository “components”. For example '("main" "contrib").

generate-cache? (default: #t)

Whether to automatically cache the generated debootstrap archive.

clean-cache (default: 14)

Discard the cache after this amount of days. Use #f to never clear the cache.

partition-style (default: 'msdos)

The type of partition to create. When set, it must be one of 'msdos, 'none or a string.

partition-alignment (default: 2048)

Alignment of the partition in sectors.

Scheme Procedure: debootstrap-variant name configuration

This is a helper procedure that creates a ganeti-os-variant record. It takes two parameters: a name and a debootstrap-configuration object.

Scheme Procedure: debootstrap-os variants

This is a helper procedure that creates a ganeti-os record. It takes a list of variants created with debootstrap-variant.

Scheme Procedure: guix-variant name configuration

This is a helper procedure that creates a ganeti-os-variant record for use with the Guix OS provider. It takes a name and a G-expression that returns a “file-like” (see file-like objects) object containing a Guix System configuration.

Scheme Procedure: guix-os variants

This is a helper procedure that creates a ganeti-os record. It takes a list of variants produced by guix-variant.

Scheme Variable: %default-debootstrap-variants

This is a convenience variable to make the debootstrap provider work “out of the box” without users having to declare variants manually. It contains a single debootstrap variant with the default configuration:

Scheme Variable: %default-guix-variants

This is a convenience variable to make the Guix OS provider work without additional configuration. It creates a virtual machine that has an SSH server, a serial console, and authorizes the Ganeti hosts SSH keys.

(list (guix-variant
       "default"
       (file-append ganeti-instance-guix
                    "/share/doc/ganeti-instance-guix/examples/dynamic.scm")))

Users can implement support for OS providers unbeknownst to Guix by extending the ganeti-os and ganeti-os-variant records appropriately. For example:

(ganeti-os
 (name "custom")
 (extension ".conf")
 (variants
  (list (ganeti-os-variant
         (name "foo")
         (configuration (plain-file "bar" "this is fine"))))))

That creates /etc/ganeti/instance-custom/variants/foo.conf which points to a file in the store with contents this is fine. It also creates /etc/ganeti/instance-custom/variants/variants.list with contents foo.

Obviously this may not work for all OS providers out there. If you find the interface limiting, please reach out to guix-devel@gnu.org.

The rest of this section documents the various services that are included by ganeti-service-type.

Scheme Variable: ganeti-noded-service-type

ganeti-noded is the daemon responsible for node-specific functions within the Ganeti system. The value of this service must be a ganeti-noded-configuration object.

Data Type: ganeti-noded-configuration

This is the configuration for the ganeti-noded service.

ganeti (default: ganeti)

The ganeti package to use for this service.

port (default: 1811)

The TCP port on which the node daemon listens for network requests.

address (default: "0.0.0.0")

The network address that the daemon will bind to. The default address means bind to all available addresses.

interface (default: #f)

When this is set, it must be a specific network interface (e.g. eth0) that the daemon will bind to.

max-clients (default: 20)

This sets a limit on the maximum number of simultaneous client connections that the daemon will handle. Connections above this count are accepted, but no responses will be sent until enough connections have closed.

ssl? (default: #t)

Whether to use SSL/TLS to encrypt network communications. The certificate is automatically provisioned by the cluster and can be rotated with gnt-cluster renew-crypto.

ssl-key (default: "/var/lib/ganeti/server.pem")

This can be used to provide a specific encryption key for TLS communications.

ssl-cert (default: "/var/lib/ganeti/server.pem")

This can be used to provide a specific certificate for TLS communications.

debug? (default: #f)

When true, the daemon performs additional logging for debugging purposes. Note that this will leak encryption details to the log files, use with caution.

Scheme Variable: ganeti-confd-service-type

ganeti-confd answers queries related to the configuration of a Ganeti cluster. The purpose of this daemon is to have a highly available and fast way to query cluster configuration values. It is automatically active on all master candidates. The value of this service must be a ganeti-confd-configuration object.

Data Type: ganeti-confd-configuration

This is the configuration for the ganeti-confd service.

ganeti (default: ganeti)

The ganeti package to use for this service.

port (default: 1814)

The UDP port on which to listen for network requests.

address (default: "0.0.0.0")

Network address that the daemon will bind to.

debug? (default: #f)

When true, the daemon performs additional logging for debugging purposes.

Scheme Variable: ganeti-wconfd-service-type

ganeti-wconfd is the daemon that has authoritative knowledge about the cluster configuration and is the only entity that can accept changes to it. All jobs that need to modify the configuration will do so by sending appropriate requests to this daemon. It only runs on the master node and will automatically disable itself on other nodes.

The value of this service must be a ganeti-wconfd-configuration object.

Data Type: ganeti-wconfd-configuration

This is the configuration for the ganeti-wconfd service.

ganeti (default: ganeti)

The ganeti package to use for this service.

no-voting? (default: #f)

The daemon will refuse to start if the majority of cluster nodes does not agree that it is running on the master node. Set to #t to start even if a quorum can not be reached (dangerous, use with caution).

debug? (default: #f)

When true, the daemon performs additional logging for debugging purposes.

Scheme Variable: ganeti-luxid-service-type

ganeti-luxid is a daemon used to answer queries related to the configuration and the current live state of a Ganeti cluster. Additionally, it is the authoritative daemon for the Ganeti job queue. Jobs can be submitted via this daemon and it schedules and starts them.

It takes a ganeti-luxid-configuration object.

Data Type: ganeti-luxid-configuration

This is the configuration for the ganeti-wconfd service.

ganeti (default: ganeti)

The ganeti package to use for this service.

no-voting? (default: #f)

The daemon will refuse to start if it cannot verify that the majority of cluster nodes believes that it is running on the master node. Set to #t to ignore such checks and start anyway (this can be dangerous).

debug? (default: #f)

When true, the daemon performs additional logging for debugging purposes.

Scheme Variable: ganeti-rapi-service-type

ganeti-rapi provides a remote API for Ganeti clusters. It runs on the master node and can be used to perform cluster actions programmatically via a JSON-based RPC protocol.

Most query operations are allowed without authentication (unless require-authentication? is set), whereas write operations require explicit authorization via the /var/lib/ganeti/rapi/users file. See the Ganeti Remote API documentation for more information.

The value of this service must be a ganeti-rapi-configuration object.

Data Type: ganeti-rapi-configuration

This is the configuration for the ganeti-rapi service.

ganeti (default: ganeti)

The ganeti package to use for this service.

require-authentication? (default: #f)

Whether to require authentication even for read-only operations.

port (default: 5080)

The TCP port on which to listen to API requests.

address (default: "0.0.0.0")

The network address that the service will bind to. By default it listens on all configured addresses.

interface (default: #f)

When set, it must specify a specific network interface such as eth0 that the daemon will bind to.

max-clients (default: 20)

The maximum number of simultaneous client requests to handle. Further connections are allowed, but no responses are sent until enough connections have closed.

ssl? (default: #t)

Whether to use SSL/TLS encryption on the RAPI port.

ssl-key (default: "/var/lib/ganeti/server.pem")

This can be used to provide a specific encryption key for TLS communications.

ssl-cert (default: "/var/lib/ganeti/server.pem")

This can be used to provide a specific certificate for TLS communications.

debug? (default: #f)

When true, the daemon performs additional logging for debugging purposes. Note that this will leak encryption details to the log files, use with caution.

Scheme Variable: ganeti-kvmd-service-type

ganeti-kvmd is responsible for determining whether a given KVM instance was shut down by an administrator or a user. Normally Ganeti will restart an instance that was not stopped through Ganeti itself. If the cluster option user_shutdown is true, this daemon monitors the QMP socket provided by QEMU and listens for shutdown events, and marks the instance as USER_down instead of ERROR_down when it shuts down gracefully by itself.

It takes a ganeti-kvmd-configuration object.

Data Type: ganeti-kvmd-configuration
ganeti (default: ganeti)

The ganeti package to use for this service.

debug? (default: #f)

When true, the daemon performs additional logging for debugging purposes.

Scheme Variable: ganeti-mond-service-type

ganeti-mond is an optional daemon that provides Ganeti monitoring functionality. It is responsible for running data collectors and publish the collected information through a HTTP interface.

It takes a ganeti-mond-configuration object.

Data Type: ganeti-mond-configuration
ganeti (default: ganeti)

The ganeti package to use for this service.

port (default: 1815)

The port on which the daemon will listen.

address (default: "0.0.0.0")

The network address that the daemon will bind to. By default it binds to all available interfaces.

debug? (default: #f)

When true, the daemon performs additional logging for debugging purposes.

Scheme Variable: ganeti-metad-service-type

ganeti-metad is an optional daemon that can be used to provide information about the cluster to instances or OS install scripts.

It takes a ganeti-metad-configuration object.

Data Type: ganeti-metad-configuration
ganeti (default: ganeti)

The ganeti package to use for this service.

port (default: 80)

The port on which the daemon will listen.

address (default: #f)

If set, the daemon will bind to this address only. If left unset, the behavior depends on the cluster configuration.

debug? (default: #f)

When true, the daemon performs additional logging for debugging purposes.

Scheme Variable: ganeti-watcher-service-type

ganeti-watcher is a script designed to run periodically and ensure the health of a cluster. It will automatically restart instances that have stopped without Ganeti’s consent, and repairs DRBD links in case a node has rebooted. It also archives old cluster jobs and restarts Ganeti daemons that are not running. If the cluster parameter ensure_node_health is set, the watcher will also shutdown instances and DRBD devices if the node it is running on is declared offline by known master candidates.

It can be paused on all nodes with gnt-cluster watcher pause.

The service takes a ganeti-watcher-configuration object.

Data Type: ganeti-watcher-configuration
ganeti (default: ganeti)

The ganeti package to use for this service.

schedule (default: '(next-second-from (next-minute (range 0 60 5))))

How often to run the script. The default is every five minutes.

rapi-ip (default: #f)

This option needs to be specified only if the RAPI daemon is configured to use a particular interface or address. By default the cluster address is used.

job-age (default: (* 6 3600))

Archive cluster jobs older than this age, specified in seconds. The default is 6 hours. This keeps gnt-job list manageable.

verify-disks? (default: #t)

If this is #f, the watcher will not try to repair broken DRBD links automatically. Administrators will need to use gnt-cluster verify-disks manually instead.

debug? (default: #f)

When #t, the script performs additional logging for debugging purposes.

Scheme Variable: ganeti-cleaner-service-type

ganeti-cleaner is a script designed to run periodically and remove old files from the cluster. This service type controls two cron jobs: one intended for the master node that permanently purges old cluster jobs, and one intended for every node that removes expired X509 certificates, keys, and outdated ganeti-watcher information. Like all Ganeti services, it is safe to include even on non-master nodes as it will disable itself as necessary.

It takes a ganeti-cleaner-configuration object.

Data Type: ganeti-cleaner-configuration
ganeti (default: ganeti)

The ganeti package to use for the gnt-cleaner command.

master-schedule (default: "45 1 * * *")

How often to run the master cleaning job. The default is once per day, at 01:45:00.

node-schedule (default: "45 2 * * *")

How often to run the node cleaning job. The default is once per day, at 02:45:00.


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