2885c3568e
Previously, '&inferior-exception' raised by 'upgrade-shepherd-services' and co. would go through as-is, leaving users with an ugly backtrace. * gnu/machine/ssh.scm (deploy-managed-host): Define 'eval/error-handling' and use it in lieu of EVAL as arguments to 'switch-to-system', 'upgrade-shepherd-services', and 'install-bootloader'.
577 lines
24 KiB
Scheme
577 lines
24 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, 2021 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 ((gnu services) #:select (sexp->system-provenance))
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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 ((guix self) #:select (make-config.scm))
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#:use-module ((guix inferior)
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#:select (inferior-exception?
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inferior-exception-arguments))
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#:use-module (gcrypt pk-crypto)
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#:use-module (ice-9 format)
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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-allow-downgrades?
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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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(allow-downgrades? machine-ssh-configuration-allow-downgrades? ; boolean
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(default #f))
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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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;; Don't try to validate network file systems.
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(not (string-prefix? "nfs" (file-system-type fs)))
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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 #$(file-system-device fs))
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#t)
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(lambda args
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(system-error-errno args)))))
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(when (number? errno)
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(raise (formatted-message (G_ "device '~a' not found: ~a")
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(file-system-device fs)
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(strerror errno))))))
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(define (check-labeled-file-system fs)
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(define remote-exp
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(with-imported-modules (source-module-closure
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'((gnu build file-systems)))
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#~(begin
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(use-modules (gnu build file-systems))
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(find-partition-by-label #$(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 (formatted-message (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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(let ((uuid (uuid #$(uuid->string (file-system-device fs))
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'#$(uuid-type (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 (formatted-message (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 (formatted-message (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-forward-update machine)
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"Check whether we are making a forward update for MACHINE. Depending on its
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'allow-upgrades?' field, raise an error or display a warning if we are
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potentially downgrading it."
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(define config
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(machine-configuration machine))
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(define validate-reconfigure
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(if (machine-ssh-configuration-allow-downgrades? config)
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warn-about-backward-reconfigure
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ensure-forward-reconfigure))
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(remote-let ((provenance #~(call-with-input-file
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"/run/current-system/provenance"
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read)))
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(define channels
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(sexp->system-provenance provenance))
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(check-forward-update validate-reconfigure
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#:current-channels channels)))
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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 (formatted-message (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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(list (machine-check-forward-update 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 not-config?
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;; Select (guix …) and (gnu …) modules, except (guix config).
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(match-lambda
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(('guix 'config) #f)
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(('guix _ ...) #t)
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(('gnu _ ...) #t)
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(_ #f)))
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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 `(((guix config) => ,(make-config.scm))
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,@(source-module-closure
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'((guix profiles))
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#:select? not-config?))
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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 ...)
|
||
"Catch exceptions that arise when binding MBODY, a monadic expression in
|
||
%STORE-MONAD, and collect their arguments in a &deploy-error condition, with
|
||
the 'should-roll-back' field set to SHOULD-ROLL-BACK?"
|
||
(catch #t
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||
(lambda ()
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||
mbody ...)
|
||
(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)
|
||
"Internal implementation of 'deploy-machine' for MACHINE instances with an
|
||
environment type of 'managed-host."
|
||
(maybe-raise-unsupported-configuration-error machine)
|
||
(when (machine-ssh-configuration-authorize?
|
||
(machine-configuration machine))
|
||
(unless (file-exists? %public-key-file)
|
||
(raise (formatted-message (G_ "no signing key '~a'. \
|
||
have you run 'guix archive --generate-key?'")
|
||
%public-key-file)))
|
||
(remote-authorize-signing-key (call-with-input-file %public-key-file
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||
(lambda (port)
|
||
(string->canonical-sexp
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||
(get-string-all port))))
|
||
(machine-ssh-session machine)
|
||
(machine-become-command machine)))
|
||
(mlet %store-monad ((_ (check-deployment-sanity machine))
|
||
(boot-parameters (machine-boot-parameters machine)))
|
||
(let* ((os (machine-operating-system machine))
|
||
(host (machine-ssh-configuration-host-name
|
||
(machine-configuration machine)))
|
||
(eval (cut machine-remote-eval machine <>))
|
||
(menu-entries (map boot-parameters->menu-entry boot-parameters))
|
||
(bootloader-configuration (operating-system-bootloader os))
|
||
(bootcfg (operating-system-bootcfg os menu-entries)))
|
||
(define-syntax-rule (eval/error-handling condition handler ...)
|
||
;; Return a wrapper around EVAL such that HANDLER is evaluated if an
|
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;; exception is raised.
|
||
(lambda (exp)
|
||
(lambda (store)
|
||
(guard (condition ((inferior-exception? condition)
|
||
(values (begin handler ...) store)))
|
||
(run-with-store store (eval exp))))))
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||
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||
(mbegin %store-monad
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||
(with-roll-back #f
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||
(switch-to-system (eval/error-handling c
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||
(raise (formatted-message
|
||
(G_ "\
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failed to switch systems while deploying '~a':~%~{~s ~}")
|
||
host
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||
(inferior-exception-arguments c))))
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||
os))
|
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(with-roll-back #t
|
||
(mbegin %store-monad
|
||
(upgrade-shepherd-services (eval/error-handling c
|
||
(warning (G_ "\
|
||
an error occurred while upgrading services on '~a':~%~{~s ~}~%")
|
||
host
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||
(inferior-exception-arguments
|
||
c)))
|
||
os)
|
||
(install-bootloader (eval/error-handling c
|
||
(raise (formatted-message
|
||
(G_ "\
|
||
failed to install bootloader on '~a':~%~{~s ~}~%")
|
||
host
|
||
(inferior-exception-arguments c))))
|
||
bootloader-configuration bootcfg)))))))
|
||
|
||
|
||
;;;
|
||
;;; Roll-back.
|
||
;;;
|
||
|
||
(define (roll-back-managed-host machine)
|
||
"Internal implementation of 'roll-back-machine' for MACHINE instances with
|
||
an environment type of 'managed-host."
|
||
(define remote-exp
|
||
(with-extensions (list guile-gcrypt)
|
||
(with-imported-modules (source-module-closure '((guix config)
|
||
(guix profiles)))
|
||
#~(begin
|
||
(use-modules (guix config)
|
||
(guix profiles))
|
||
|
||
(define %system-profile
|
||
(string-append %state-directory "/profiles/system"))
|
||
|
||
(define target-generation
|
||
(relative-generation %system-profile -1))
|
||
|
||
(if target-generation
|
||
(switch-to-generation %system-profile target-generation)
|
||
'error)))))
|
||
|
||
(define roll-back-failure
|
||
(condition (&message (message (G_ "could not roll-back machine")))))
|
||
|
||
(mlet* %store-monad ((boot-parameters (machine-boot-parameters machine))
|
||
(_ -> (if (< (length boot-parameters) 2)
|
||
(raise roll-back-failure)))
|
||
(entries -> (map boot-parameters->menu-entry
|
||
(list (second boot-parameters))))
|
||
(locale -> (boot-parameters-locale
|
||
(second boot-parameters)))
|
||
(crypto-dev -> (boot-parameters-store-crypto-devices
|
||
(second boot-parameters)))
|
||
(store-dir -> (boot-parameters-store-directory-prefix
|
||
(second boot-parameters)))
|
||
(old-entries -> (map boot-parameters->menu-entry
|
||
(drop boot-parameters 2)))
|
||
(bootloader -> (operating-system-bootloader
|
||
(machine-operating-system machine)))
|
||
(bootcfg (lower-object
|
||
((bootloader-configuration-file-generator
|
||
(bootloader-configuration-bootloader
|
||
bootloader))
|
||
bootloader entries
|
||
#:locale locale
|
||
#:store-crypto-devices crypto-dev
|
||
#:store-directory-prefix store-dir
|
||
#:old-entries old-entries)))
|
||
(remote-result (machine-remote-eval machine remote-exp)))
|
||
(when (eqv? 'error remote-result)
|
||
(raise roll-back-failure))))
|
||
|
||
|
||
;;;
|
||
;;; Environment type.
|
||
;;;
|
||
|
||
(define managed-host-environment-type
|
||
(environment-type
|
||
(machine-remote-eval managed-host-remote-eval)
|
||
(deploy-machine deploy-managed-host)
|
||
(roll-back-machine roll-back-managed-host)
|
||
(name 'managed-host-environment-type)
|
||
(description "Provisioning for machines that are accessible over SSH
|
||
and have a known host-name. This entails little more than maintaining an SSH
|
||
connection to the host.")))
|
||
|
||
(define (maybe-raise-unsupported-configuration-error machine)
|
||
"Raise an error if MACHINE's configuration is not an instance of
|
||
<machine-ssh-configuration>."
|
||
(let ((config (machine-configuration machine))
|
||
(environment (environment-type-name (machine-environment machine))))
|
||
(unless (and config (machine-ssh-configuration? config))
|
||
(raise (formatted-message (G_ "unsupported machine configuration '~a'
|
||
for environment of type '~a'")
|
||
config
|
||
environment)))))
|
||
|
||
;; Local Variables:
|
||
;; eval: (put 'remote-let 'scheme-indent-function 1)
|
||
;; eval: (put 'with-roll-back 'scheme-indent-function 1)
|
||
;; eval: (put 'eval/error-handling 'scheme-indent-function 1)
|
||
;; End:
|