8bc745052e
* gnu/machine/ssh.scm (machine-check-initrd-modules): Improve message upon module mismatch.
505 lines
21 KiB
Scheme
505 lines
21 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2019 Jakob L. Kreuze <zerodaysfordays@sdf.org>
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;;; Copyright © 2020 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu machine ssh)
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#:use-module (gnu bootloader)
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#:use-module (gnu machine)
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#:autoload (gnu packages gnupg) (guile-gcrypt)
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#:use-module (gnu system)
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#:use-module (gnu system file-systems)
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#:use-module (gnu system uuid)
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#:use-module (guix diagnostics)
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#:use-module (guix gexp)
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#:use-module (guix i18n)
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#:use-module (guix modules)
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#:use-module (guix monads)
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#:use-module (guix pki)
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#:use-module (guix records)
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#:use-module (guix remote)
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#:use-module (guix scripts system reconfigure)
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#:use-module (guix ssh)
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#:use-module (guix store)
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#:use-module (guix utils)
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#:use-module (gcrypt pk-crypto)
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#:use-module (ice-9 match)
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#:use-module (ice-9 textual-ports)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-9)
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#:use-module (srfi srfi-19)
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#:use-module (srfi srfi-26)
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#:use-module (srfi srfi-34)
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#:use-module (srfi srfi-35)
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#:export (managed-host-environment-type
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machine-ssh-configuration
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machine-ssh-configuration?
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machine-ssh-configuration
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machine-ssh-configuration-host-name
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machine-ssh-configuration-build-locally?
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machine-ssh-configuration-authorize?
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machine-ssh-configuration-port
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machine-ssh-configuration-user
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machine-ssh-configuration-host-key
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machine-ssh-configuration-session))
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;;; Commentary:
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;;;
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;;; This module implements remote evaluation and system deployment for
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;;; machines that are accessible over SSH and have a known host-name. In the
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;;; sense of the broader "machine" interface, we describe the environment for
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;;; such machines as 'managed-host.
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;;;
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;;; Code:
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;;;
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;;; Parameters for the SSH client.
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;;;
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(define-record-type* <machine-ssh-configuration> machine-ssh-configuration
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make-machine-ssh-configuration
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machine-ssh-configuration?
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(host-name machine-ssh-configuration-host-name) ; string
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(system machine-ssh-configuration-system) ; string
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(build-locally? machine-ssh-configuration-build-locally? ; boolean
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(default #t))
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(authorize? machine-ssh-configuration-authorize? ; boolean
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(default #t))
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(port machine-ssh-configuration-port ; integer
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(default 22))
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(user machine-ssh-configuration-user ; string
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(default "root"))
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(identity machine-ssh-configuration-identity ; path to a private key
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(default #f))
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(session machine-ssh-configuration-session ; session
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(default #f))
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(host-key machine-ssh-configuration-host-key ; #f | string
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(default #f)))
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(define (machine-ssh-session machine)
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"Return the SSH session that was given in MACHINE's configuration, or create
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one from the configuration's parameters if one was not provided."
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(maybe-raise-unsupported-configuration-error machine)
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(let ((config (machine-configuration machine)))
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(or (machine-ssh-configuration-session config)
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(let ((host-name (machine-ssh-configuration-host-name config))
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(user (machine-ssh-configuration-user config))
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(port (machine-ssh-configuration-port config))
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(identity (machine-ssh-configuration-identity config))
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(host-key (machine-ssh-configuration-host-key config)))
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(unless host-key
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(warning (G_ "<machine-ssh-configuration> without a 'host-key' \
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is deprecated~%")))
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(open-ssh-session host-name
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#:user user
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#:port port
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#:identity identity
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#:host-key host-key)))))
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;;;
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;;; Remote evaluation.
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;;;
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(define (machine-become-command machine)
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"Return as a list of strings the program and arguments necessary to run a
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shell command with escalated privileges for MACHINE's configuration."
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(if (string= "root" (machine-ssh-configuration-user
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(machine-configuration machine)))
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'()
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'("/run/setuid-programs/sudo" "-n" "--")))
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(define (managed-host-remote-eval machine exp)
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"Internal implementation of 'machine-remote-eval' for MACHINE instances with
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an environment type of 'managed-host."
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(maybe-raise-unsupported-configuration-error machine)
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(let ((config (machine-configuration machine)))
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(remote-eval exp (machine-ssh-session machine)
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#:build-locally?
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(machine-ssh-configuration-build-locally? config)
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#:system
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(machine-ssh-configuration-system config)
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#:become-command
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(machine-become-command machine))))
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;;;
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;;; Safety checks.
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;;;
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;; Assertion to be executed remotely. This abstraction exists to allow us to
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;; gather a list of expressions to be evaluated and eventually evaluate them
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;; all at once instead of one by one. (This is pretty much a monad.)
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(define-record-type <remote-assertion>
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(remote-assertion exp proc)
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remote-assertion?
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(exp remote-assertion-expression)
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(proc remote-assertion-procedure))
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(define-syntax-rule (remote-let ((var exp)) body ...)
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"Return a <remote-assertion> that binds VAR to the result of evaluating EXP,
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a gexp, remotely, and evaluate BODY in that context."
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(remote-assertion exp (lambda (var) body ...)))
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(define (machine-check-file-system-availability machine)
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"Return a list of <remote-assertion> that raise a '&message' error condition
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if any of the file-systems specified in MACHINE's 'system' declaration do not
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exist on the machine."
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(define file-systems
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(filter (lambda (fs)
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(and (file-system-mount? fs)
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(not (member (file-system-type fs)
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%pseudo-file-system-types))
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(not (memq 'bind-mount (file-system-flags fs)))))
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(operating-system-file-systems (machine-operating-system machine))))
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(define (check-literal-file-system fs)
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(remote-let ((errno #~(catch 'system-error
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(lambda ()
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(stat #$(file-system-device fs))
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#t)
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(lambda args
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(system-error-errno args)))))
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(when (number? errno)
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(raise (condition
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(&message
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(message (format #f (G_ "device '~a' not found: ~a")
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(file-system-device fs)
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(strerror errno)))))))))
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(define (check-labeled-file-system fs)
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(define remote-exp
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(with-imported-modules (source-module-closure
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'((gnu build file-systems)))
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#~(begin
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(use-modules (gnu build file-systems))
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(find-partition-by-label #$(file-system-label->string
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(file-system-device fs))))))
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(remote-let ((result remote-exp))
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(unless result
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(raise (condition
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(&message
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(message (format #f (G_ "no file system with label '~a'")
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(file-system-label->string
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(file-system-device fs))))))))))
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(define (check-uuid-file-system fs)
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(define remote-exp
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(with-imported-modules (source-module-closure
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'((gnu build file-systems)
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(gnu system uuid)))
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#~(begin
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(use-modules (gnu build file-systems)
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(gnu system uuid))
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(define uuid
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(string->uuid #$(uuid->string (file-system-device fs))))
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(find-partition-by-uuid uuid))))
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(remote-let ((result remote-exp))
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(unless result
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(raise (condition
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(&message
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(message (format #f (G_ "no file system with UUID '~a'")
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(uuid->string (file-system-device fs))))))))))
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(append (map check-literal-file-system
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(filter (lambda (fs)
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(string? (file-system-device fs)))
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file-systems))
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(map check-labeled-file-system
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(filter (lambda (fs)
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(file-system-label? (file-system-device fs)))
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file-systems))
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(map check-uuid-file-system
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(filter (lambda (fs)
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(uuid? (file-system-device fs)))
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file-systems))))
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(define (machine-check-initrd-modules machine)
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"Return a list of <remote-assertion> that raise a '&message' error condition
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if any of the modules needed by 'needed-for-boot' file systems in MACHINE are
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not available in the initrd."
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(define file-systems
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(filter file-system-needed-for-boot?
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(operating-system-file-systems (machine-operating-system machine))))
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(define (missing-modules fs)
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(define remote-exp
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(let ((device (file-system-device fs)))
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(with-imported-modules (source-module-closure
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'((gnu build file-systems)
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(gnu build linux-modules)
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(gnu system uuid)))
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#~(begin
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(use-modules (gnu build file-systems)
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(gnu build linux-modules)
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(gnu system uuid))
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(define dev
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#$(cond ((string? device) device)
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((uuid? device) #~(find-partition-by-uuid
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(string->uuid
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#$(uuid->string device))))
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((file-system-label? device)
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#~(find-partition-by-label
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#$(file-system-label->string device)))))
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(missing-modules dev '#$(operating-system-initrd-modules
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(machine-operating-system machine)))))))
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(remote-let ((missing remote-exp))
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(unless (null? missing)
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(raise (condition
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(&message
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(message (format #f (G_ "missing modules for ~a:~{ ~a~}~%")
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(file-system-device fs)
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missing))))))))
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(map missing-modules file-systems))
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(define (machine-check-building-for-appropriate-system machine)
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"Raise a '&message' error condition if MACHINE is configured to be built
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locally and the 'system' field does not match the '%current-system' reported
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by MACHINE."
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(let ((config (machine-configuration machine))
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(system (remote-system (machine-ssh-session machine))))
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(when (and (machine-ssh-configuration-build-locally? config)
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(not (string= system (machine-ssh-configuration-system config))))
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(raise (condition
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(&message
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(message (format #f (G_ "incorrect target system\
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('~a' was given, while the system reports that it is '~a')~%")
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(machine-ssh-configuration-system config)
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system))))))))
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(define (check-deployment-sanity machine)
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"Raise a '&message' error condition if it is clear that deploying MACHINE's
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'system' declaration would fail."
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(define assertions
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(append (machine-check-file-system-availability machine)
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(machine-check-initrd-modules machine)))
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(define aggregate-exp
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;; Gather all the expressions so that a single round-trip is enough to
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;; evaluate all the ASSERTIONS remotely.
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#~(map (lambda (file)
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(false-if-exception (primitive-load file)))
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'#$(map (lambda (assertion)
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(scheme-file "remote-assertion.scm"
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(remote-assertion-expression assertion)))
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assertions)))
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;; First check MACHINE's system type--an incorrect value for 'system' would
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;; cause subsequent invocations of 'remote-eval' to fail.
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(machine-check-building-for-appropriate-system machine)
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(mlet %store-monad ((values (machine-remote-eval machine aggregate-exp)))
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(for-each (lambda (proc value)
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(proc value))
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(map remote-assertion-procedure assertions)
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values)
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(return #t)))
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;;;
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;;; System deployment.
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;;;
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(define (machine-boot-parameters machine)
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"Monadic procedure returning a list of 'boot-parameters' for the generations
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of MACHINE's system profile, ordered from most recent to oldest."
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(define bootable-kernel-arguments
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(@@ (gnu system) bootable-kernel-arguments))
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(define remote-exp
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(with-extensions (list guile-gcrypt)
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(with-imported-modules (source-module-closure '((guix config)
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(guix profiles)))
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#~(begin
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(use-modules (guix config)
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(guix profiles)
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(ice-9 textual-ports))
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(define %system-profile
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(string-append %state-directory "/profiles/system"))
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(define (read-file path)
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(call-with-input-file path
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(lambda (port)
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(get-string-all port))))
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(map (lambda (generation)
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(let* ((system-path (generation-file-name %system-profile
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generation))
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(boot-parameters-path (string-append system-path
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"/parameters"))
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(time (stat:mtime (lstat system-path))))
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(list generation
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system-path
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time
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(read-file boot-parameters-path))))
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(reverse (generation-numbers %system-profile)))))))
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(mlet* %store-monad ((generations (machine-remote-eval machine remote-exp)))
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(return
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(map (lambda (generation)
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(match generation
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((generation system-path time serialized-params)
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(let* ((params (call-with-input-string serialized-params
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read-boot-parameters))
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(root (boot-parameters-root-device params))
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(label (boot-parameters-label params)))
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(boot-parameters
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(inherit params)
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(label
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(string-append label " (#"
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(number->string generation) ", "
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(let ((time (make-time time-utc 0 time)))
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(date->string (time-utc->date time)
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"~Y-~m-~d ~H:~M"))
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")"))
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(kernel-arguments
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(append (bootable-kernel-arguments system-path root)
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(boot-parameters-kernel-arguments params))))))))
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generations))))
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(define-syntax-rule (with-roll-back should-roll-back? mbody ...)
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"Catch exceptions that arise when binding MBODY, a monadic expression in
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%STORE-MONAD, and collect their arguments in a &deploy-error condition, with
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the 'should-roll-back' field set to SHOULD-ROLL-BACK?"
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(catch #t
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(lambda ()
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mbody ...)
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(lambda args
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(raise (condition (&deploy-error
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(should-roll-back should-roll-back?)
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(captured-args args)))))))
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(define (deploy-managed-host machine)
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"Internal implementation of 'deploy-machine' for MACHINE instances with an
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environment type of 'managed-host."
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(maybe-raise-unsupported-configuration-error machine)
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(when (machine-ssh-configuration-authorize?
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(machine-configuration machine))
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(unless (file-exists? %public-key-file)
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(raise (condition
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(&message
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(message (format #f (G_ "no signing key '~a'. \
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have you run 'guix archive --generate-key?'")
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%public-key-file))))))
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(remote-authorize-signing-key (call-with-input-file %public-key-file
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(lambda (port)
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(string->canonical-sexp
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(get-string-all port))))
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(machine-ssh-session machine)
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(machine-become-command machine)))
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(mlet %store-monad ((_ (check-deployment-sanity machine))
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(boot-parameters (machine-boot-parameters machine)))
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(let* ((os (machine-operating-system machine))
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(eval (cut machine-remote-eval machine <>))
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(menu-entries (map boot-parameters->menu-entry boot-parameters))
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(bootloader-configuration (operating-system-bootloader os))
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(bootcfg (operating-system-bootcfg os menu-entries)))
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(mbegin %store-monad
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(with-roll-back #f
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(switch-to-system eval os))
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(with-roll-back #t
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(mbegin %store-monad
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(upgrade-shepherd-services eval os)
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(install-bootloader eval bootloader-configuration bootcfg)))))))
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;;;
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;;; Roll-back.
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;;;
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(define (roll-back-managed-host machine)
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"Internal implementation of 'roll-back-machine' for MACHINE instances with
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an environment type of 'managed-host."
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(define remote-exp
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(with-extensions (list guile-gcrypt)
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(with-imported-modules (source-module-closure '((guix config)
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(guix profiles)))
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#~(begin
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(use-modules (guix config)
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(guix profiles))
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(define %system-profile
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(string-append %state-directory "/profiles/system"))
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(define target-generation
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(relative-generation %system-profile -1))
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(if target-generation
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(switch-to-generation %system-profile target-generation)
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'error)))))
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(define roll-back-failure
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(condition (&message (message (G_ "could not roll-back machine")))))
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(mlet* %store-monad ((boot-parameters (machine-boot-parameters machine))
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(_ -> (if (< (length boot-parameters) 2)
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(raise roll-back-failure)))
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(entries -> (map boot-parameters->menu-entry
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(list (second boot-parameters))))
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(old-entries -> (map boot-parameters->menu-entry
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(drop boot-parameters 2)))
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(bootloader -> (operating-system-bootloader
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(machine-operating-system machine)))
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(bootcfg (lower-object
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((bootloader-configuration-file-generator
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(bootloader-configuration-bootloader
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bootloader))
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bootloader entries
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#:old-entries old-entries)))
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(remote-result (machine-remote-eval machine remote-exp)))
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(when (eqv? 'error remote-result)
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(raise roll-back-failure))))
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;;;
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;;; Environment type.
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;;;
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(define managed-host-environment-type
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(environment-type
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(machine-remote-eval managed-host-remote-eval)
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(deploy-machine deploy-managed-host)
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(roll-back-machine roll-back-managed-host)
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(name 'managed-host-environment-type)
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(description "Provisioning for machines that are accessible over SSH
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and have a known host-name. This entails little more than maintaining an SSH
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connection to the host.")))
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(define (maybe-raise-unsupported-configuration-error machine)
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"Raise an error if MACHINE's configuration is not an instance of
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||
<machine-ssh-configuration>."
|
||
(let ((config (machine-configuration machine))
|
||
(environment (environment-type-name (machine-environment machine))))
|
||
(unless (and config (machine-ssh-configuration? config))
|
||
(raise (condition
|
||
(&message
|
||
(message (format #f (G_ "unsupported machine configuration '~a'
|
||
for environment of type '~a'")
|
||
config
|
||
environment))))))))
|