370 lines
15 KiB
Scheme
370 lines
15 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2019 Jakob L. Kreuze <zerodaysfordays@sdf.lonestar.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 services)
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#:use-module (gnu services shepherd)
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#:use-module (gnu system)
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#:use-module (guix derivations)
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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 records)
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#:use-module (guix remote)
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#:use-module (guix ssh)
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#:use-module (guix store)
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#:use-module (ice-9 match)
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#:use-module (srfi srfi-19)
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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-port
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machine-ssh-configuration-user
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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 accessable 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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this-machine-ssh-configuration
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(host-name machine-ssh-configuration-host-name) ; string
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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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(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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(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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;;;
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;;; Remote evaluation.
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;;;
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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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(remote-eval exp (machine-ssh-session machine)))
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;;;
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;;; System deployment.
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;;;
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(define (switch-to-system machine)
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"Monadic procedure creating a new generation on MACHINE and execute the
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activation script for the new system configuration."
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(define (remote-exp drv script)
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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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(guix utils)))
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#~(begin
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(use-modules (guix config)
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(guix profiles)
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(guix utils))
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(define %system-profile
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(string-append %state-directory "/profiles/system"))
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(let* ((system #$drv)
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(number (1+ (generation-number %system-profile)))
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(generation (generation-file-name %system-profile number)))
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(switch-symlinks generation system)
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(switch-symlinks %system-profile generation)
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;; The implementation of 'guix system reconfigure' saves the
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;; load path and environment here. This is unnecessary here
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;; because each invocation of 'remote-eval' runs in a distinct
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;; Guile REPL.
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(setenv "GUIX_NEW_SYSTEM" system)
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;; The activation script may write to stdout, which confuses
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;; 'remote-eval' when it attempts to read a result from the
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;; remote REPL. We work around this by forcing the output to a
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;; string.
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(with-output-to-string
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(lambda ()
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(primitive-load #$script))))))))
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(let* ((os (machine-system machine))
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(script (operating-system-activation-script os)))
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(mlet* %store-monad ((drv (operating-system-derivation os)))
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(machine-remote-eval machine (remote-exp drv script)))))
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;; XXX: Currently, this does NOT attempt to restart running services. This is
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;; also the case with 'guix system reconfigure'.
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;;
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;; See <https://issues.guix.info/issue/33508>.
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(define (upgrade-shepherd-services machine)
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"Monadic procedure unloading and starting services on the remote as needed
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to realize the MACHINE's system configuration."
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(define target-services
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;; Monadic expression evaluating to a list of (name output-path) pairs for
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;; all of MACHINE's services.
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(mapm %store-monad
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(lambda (service)
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(mlet %store-monad ((file ((compose lower-object
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shepherd-service-file)
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service)))
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(return (list (shepherd-service-canonical-name service)
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(derivation->output-path file)))))
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(service-value
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(fold-services (operating-system-services (machine-system machine))
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#:target-type shepherd-root-service-type))))
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(define (remote-exp target-services)
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(with-imported-modules '((gnu services herd))
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#~(begin
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(use-modules (gnu services herd)
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(srfi srfi-1))
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(define running
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(filter live-service-running (current-services)))
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(define (essential? service)
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;; Return #t if SERVICE is essential and should not be unloaded
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;; under any circumstance.
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(memq (first (live-service-provision service))
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'(root shepherd)))
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(define (obsolete? service)
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;; Return #t if SERVICE can be safely unloaded.
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(and (not (essential? service))
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(every (lambda (requirements)
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(not (memq (first (live-service-provision service))
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requirements)))
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(map live-service-requirement running))))
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(define to-unload
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(filter obsolete?
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(remove (lambda (service)
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(memq (first (live-service-provision service))
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(map first '#$target-services)))
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running)))
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(define to-start
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(remove (lambda (service-pair)
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(memq (first service-pair)
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(map (compose first live-service-provision)
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running)))
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'#$target-services))
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;; Unload obsolete services.
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(for-each (lambda (service)
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(false-if-exception
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(unload-service service)))
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to-unload)
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;; Load the service files for any new services and start them.
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(load-services/safe (map second to-start))
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(for-each start-service (map first to-start))
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#t)))
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(mlet %store-monad ((target-services target-services))
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(machine-remote-eval machine (remote-exp target-services))))
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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 (install-bootloader machine)
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"Create a bootloader entry for the new system generation on MACHINE, and
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configure the bootloader to boot that generation by default."
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(define bootloader-installer-script
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(@@ (guix scripts system) bootloader-installer-script))
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(define (remote-exp installer bootcfg bootcfg-file)
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(with-extensions (list guile-gcrypt)
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(with-imported-modules (source-module-closure '((gnu build install)
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(guix store)
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(guix utils)))
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#~(begin
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(use-modules (gnu build install)
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(guix store)
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(guix utils))
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(let* ((gc-root (string-append "/" %gc-roots-directory "/bootcfg"))
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(temp-gc-root (string-append gc-root ".new")))
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(switch-symlinks temp-gc-root gc-root)
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(unless (false-if-exception
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(begin
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;; The implementation of 'guix system reconfigure'
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;; saves the load path here. This is unnecessary here
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;; because each invocation of 'remote-eval' runs in a
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;; distinct Guile REPL.
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(install-boot-config #$bootcfg #$bootcfg-file "/")
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;; The installation script may write to stdout, which
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;; confuses 'remote-eval' when it attempts to read a
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;; result from the remote REPL. We work around this
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;; by forcing the output to a string.
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(with-output-to-string
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(lambda ()
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(primitive-load #$installer)))))
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(delete-file temp-gc-root)
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(error "failed to install bootloader"))
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(rename-file temp-gc-root gc-root)
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#t)))))
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(mlet* %store-monad ((boot-parameters (machine-boot-parameters machine)))
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(let* ((os (machine-system machine))
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(bootloader ((compose bootloader-configuration-bootloader
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operating-system-bootloader)
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os))
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(bootloader-target (bootloader-configuration-target
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(operating-system-bootloader os)))
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(installer (bootloader-installer-script
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(bootloader-installer bootloader)
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(bootloader-package bootloader)
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bootloader-target
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"/"))
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(menu-entries (map boot-parameters->menu-entry boot-parameters))
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(bootcfg (operating-system-bootcfg os menu-entries))
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(bootcfg-file (bootloader-configuration-file bootloader)))
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(machine-remote-eval machine (remote-exp installer bootcfg bootcfg-file)))))
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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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(mbegin %store-monad
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(switch-to-system machine)
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(upgrade-shepherd-services machine)
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(install-bootloader machine)))
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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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(name 'managed-host-environment-type)
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(description "Provisioning for machines that are accessable 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>."
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(let ((config (machine-configuration machine))
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(environment (environment-type-name (machine-environment machine))))
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(unless (and config (machine-ssh-configuration? config))
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(raise (condition
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(&message
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(message (format #f (G_ "unsupported machine configuration '~a'
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for environment of type '~a'")
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config
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environment))))))))
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