We’ve already seen
operating-system declarations used to manage a
machine’s configuration locally. Suppose you need to configure multiple
machines, though—perhaps you’re managing a service on the web that’s
comprised of several servers.
guix deploy enables you to use those
operating-system declarations to manage multiple remote hosts at
once as a logical “deployment”.
Note: The functionality described in this section is still under development and is subject to change. Get in touch with us on firstname.lastname@example.org!
guix deploy file
Such an invocation will deploy the machines that the code within file evaluates to. As an example, file might contain a definition like this:
;; This is a Guix deployment of a "bare bones" setup, with ;; no X11 display server, to a machine with an SSH daemon ;; listening on localhost:2222. A configuration such as this ;; may be appropriate for virtual machine with ports ;; forwarded to the host's loopback interface. (use-service-modules networking ssh) (use-package-modules bootloaders) (define %system (operating-system (host-name "gnu-deployed") (timezone "Etc/UTC") (bootloader (bootloader-configuration (bootloader grub-bootloader) (targets '("/dev/vda")) (terminal-outputs '(console)))) (file-systems (cons (file-system (mount-point "/") (device "/dev/vda1") (type "ext4")) %base-file-systems)) (services (append (list (service dhcp-client-service-type) (service openssh-service-type (openssh-configuration (permit-root-login #t) (allow-empty-passwords? #t)))) %base-services)))) (list (machine (operating-system %system) (environment managed-host-environment-type) (configuration (machine-ssh-configuration (host-name "localhost") (system "x86_64-linux") (user "alice") (identity "./id_rsa") (port 2222)))))
The file should evaluate to a list of machine objects. This example,
upon being deployed, will create a new generation on the remote system
configuration specify how the machine should be
provisioned—that is, how the computing resources should be created and
managed. The above example does not create any resources, as a
'managed-host is a machine that is already running the Guix system and
available over the network. This is a particularly simple case; a more
complex deployment may involve, for example, starting virtual machines through
a Virtual Private Server (VPS) provider. In such a case, a different
environment type would be used.
Do note that you first need to generate a key pair on the coordinator machine
to allow the daemon to export signed archives of files from the store
guix archive), though this step is automatic on Guix
# guix archive --generate-key
Each target machine must authorize the key of the master machine so that it accepts store items it receives from the coordinator:
# guix archive --authorize < coordinator-public-key.txt
user, in this example, specifies the name of the user account to log in
as to perform the deployment. Its default value is
root, but root
login over SSH may be forbidden in some cases. To work around this,
guix deploy can log in as an unprivileged user and employ
sudo to escalate privileges. This will only work if
currently installed on the remote and can be invoked non-interactively as
user. That is, the line in
ability to use
sudo must contain the
NOPASSWD tag. This can
be accomplished with the following operating system configuration snippet:
(use-modules ... (gnu system)) ;for %sudoers-specification (define %user "username") (operating-system ... (sudoers-file (plain-file "sudoers" (string-append (plain-file-content %sudoers-specification) (format #f "~a ALL = NOPASSWD: ALL~%" %user)))))
For more information regarding the format of the sudoers file,
Once you’ve deployed a system on a set of machines, you may find it
useful to run a command on all of them. The --execute or
-x option lets you do that; the example below runs
uname -a on all the machines listed in the deployment file:
guix deploy file -x -- uname -a
One thing you may often need to do after deployment is restart specific services on all the machines, which you can do like so:
guix deploy file -x -- herd restart service
guix deploy -x command returns zero if and only if the
command succeeded on all the machines.
Below are the data types you need to know about when writing a deployment file.
This is the data type representing a single machine in a heterogeneous Guix deployment.
The object of the operating system configuration to deploy.
environment-type describing how the machine should be provisioned.
An object describing the configuration for the machine’s
environment has a default configuration,
#f may be used.
#f is used for an environment with no default configuration,
however, an error will be thrown.
This is the data type representing the SSH client parameters for a machine
If false, system derivations will be built on the machine being deployed to.
The system type describing the architecture of the machine being deployed
If true, the coordinator’s signing key will be added to the remote’s ACL keyring.
If specified, the path to the SSH private key to use to authenticate with the remote host.
This should be the SSH host key of the machine, which looks like this:
ssh-ed25519 AAAAC3Nz… email@example.com
#f, the server is authenticated against
the ~/.ssh/known_hosts file, just like the OpenSSH
Whether to allow potential downgrades.
guix system reconfigure,
guix deploy compares
the channel commits currently deployed on the remote host (as returned
guix system describe) to those currently in use (as
guix describe) to determine whether commits
currently in use are descendants of those deployed. When this is not
the case and
allow-downgrades? is false, it raises an error.
This ensures you do not accidentally downgrade remote machines.
Whether to perform “safety checks” before deployment. This includes
verifying that devices and file systems referred to in the operating
system configuration actually exist on the target machine, and making
sure that Linux modules required to access storage devices at boot time
are listed in the
initrd-modules field of the operating system.
These safety checks ensure that you do not inadvertently deploy a system that would fail to boot. Be careful before turning them off!
This is the data type describing the Droplet that should be created for a
machine with an
The path to the SSH private key to use to authenticate with the remote host. In the future, this field may not exist.
A list of string “tags” that uniquely identify the machine. Must be given such that no two machines in the deployment have the same set of tags.
A Digital Ocean region slug, such as
A Digital Ocean size slug, such as
Whether or not the droplet should be created with IPv6 networking.