From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:470:142:3::10]:50505) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hvUVQ-0001ex-22 for guix-patches@gnu.org; Wed, 07 Aug 2019 18:34:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hvUVO-0007XR-8y for guix-patches@gnu.org; Wed, 07 Aug 2019 18:34:03 -0400 Received: from debbugs.gnu.org ([209.51.188.43]:59043) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1hvUVO-0007XM-4i for guix-patches@gnu.org; Wed, 07 Aug 2019 18:34:02 -0400 Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1hvUVN-0004tw-Vi for guix-patches@gnu.org; Wed, 07 Aug 2019 18:34:02 -0400 Subject: [bug#36952] [PATCH v2] machine: Implement 'roll-back-machine'. Resent-Message-ID: References: <87v9v94067.fsf@sdf.lonestar.org> <87v9v8ohvq.fsf@dustycloud.org> <87v9v8k82l.fsf_-_@sdf.lonestar.org> From: Christopher Lemmer Webber In-reply-to: <87v9v8k82l.fsf_-_@sdf.lonestar.org> Date: Wed, 07 Aug 2019 18:33:22 -0400 Message-ID: <87r25wobbh.fsf@dustycloud.org> MIME-Version: 1.0 Content-Type: text/plain List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-patches-bounces+kyle=kyleam.com@gnu.org Sender: "Guix-patches" To: "Jakob L. Kreuze" , David Thompson Cc: 36952@debbugs.gnu.org Thanks. I'm going to specifically loop in Dave... Dave, mind peering over this before I merge it? Jakob L. Kreuze writes: > * gnu/machine.scm (roll-back-machine, &deploy-error, deploy-error?) > (deploy-error-should-roll-back) > (deploy-error-captured-args): New variable. > * gnu/machine/ssh.scm (roll-back-managed-host): New variable. > * guix/scripts/deploy.scm (guix-deploy): Roll-back systems when a > deployment fails. > --- > gnu/machine.scm | 27 ++++++++++++++- > gnu/machine/ssh.scm | 75 +++++++++++++++++++++++++++++++++++++++-- > guix/remote.scm | 1 + > guix/scripts/deploy.scm | 17 ++++++++-- > 4 files changed, 114 insertions(+), 6 deletions(-) > > diff --git a/gnu/machine.scm b/gnu/machine.scm > index 30ae97f6ec..05b03b21d4 100644 > --- a/gnu/machine.scm > +++ b/gnu/machine.scm > @@ -24,6 +24,7 @@ > #:use-module (guix records) > #:use-module (guix store) > #:use-module ((guix utils) #:select (source-properties->location)) > + #:use-module (srfi srfi-35) > #:export (environment-type > environment-type? > environment-type-name > @@ -40,7 +41,13 @@ > machine-display-name > > deploy-machine > - machine-remote-eval)) > + roll-back-machine > + machine-remote-eval > + > + &deploy-error > + deploy-error? > + deploy-error-should-roll-back > + deploy-error-captured-args)) > > ;;; Commentary: > ;;; > @@ -66,6 +73,7 @@ > ;; of the form '(machine-remote-eval machine exp)'. > (machine-remote-eval environment-type-machine-remote-eval) ; procedure > (deploy-machine environment-type-deploy-machine) ; procedure > + (roll-back-machine environment-type-roll-back-machine) ; procedure > > ;; Metadata. > (name environment-type-name) ; symbol > @@ -105,3 +113,20 @@ are built and deployed to MACHINE beforehand." > MACHINE, activating it on MACHINE and switching MACHINE to the new generation." > (let ((environment (machine-environment machine))) > ((environment-type-deploy-machine environment) machine))) > + > +(define (roll-back-machine machine) > + "Monadic procedure rolling back to the previous system generation on > +MACHINE. Return the number of the generation that was current before switching > +and the new generation number." > + (let ((environment (machine-environment machine))) > + ((environment-type-roll-back-machine environment) machine))) > + > + > +;;; > +;;; Error types. > +;;; > + > +(define-condition-type &deploy-error &error > + deploy-error? > + (should-roll-back deploy-error-should-roll-back) > + (captured-args deploy-error-captured-args)) > diff --git a/gnu/machine/ssh.scm b/gnu/machine/ssh.scm > index 274d56db26..ae312597dd 100644 > --- a/gnu/machine/ssh.scm > +++ b/gnu/machine/ssh.scm > @@ -17,6 +17,7 @@ > ;;; along with GNU Guix. If not, see . > > (define-module (gnu machine ssh) > + #:use-module (gnu bootloader) > #:use-module (gnu machine) > #:autoload (gnu packages gnupg) (guile-gcrypt) > #:use-module (gnu system) > @@ -34,8 +35,10 @@ > #:use-module (guix store) > #:use-module (guix utils) > #:use-module (ice-9 match) > + #:use-module (srfi srfi-1) > #:use-module (srfi srfi-19) > #:use-module (srfi srfi-26) > + #:use-module (srfi srfi-34) > #:use-module (srfi srfi-35) > #:export (managed-host-environment-type > > @@ -304,6 +307,18 @@ of MACHINE's system profile, ordered from most recent to oldest." > (boot-parameters-kernel-arguments params)))))))) > generations)))) > > +(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 > + (lambda () > + mbody ...) > + (lambda args > + (raise (condition (&deploy-error > + (should-roll-back should-roll-back?) > + (captured-args args))))))) > + > (define (deploy-managed-host machine) > "Internal implementation of 'deploy-machine' for MACHINE instances with an > environment type of 'managed-host." > @@ -316,9 +331,62 @@ environment type of 'managed-host." > (bootloader-configuration (operating-system-bootloader os)) > (bootcfg (operating-system-bootcfg os menu-entries))) > (mbegin %store-monad > - (switch-to-system eval os) > - (upgrade-shepherd-services eval os) > - (install-bootloader eval bootloader-configuration bootcfg))))) > + (with-roll-back #f > + (switch-to-system eval os)) > + (with-roll-back #t > + (mbegin %store-monad > + (upgrade-shepherd-services eval os) > + (install-bootloader eval 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-spec->number %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)))) > + (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 > + #:old-entries old-entries))) > + (eval -> (cut machine-remote-eval machine <>)) > + (remote-result (machine-remote-eval machine > + remote-exp))) > + (when (eqv? 'error remote-result) > + (raise roll-back-failure)))) > > > ;;; > @@ -329,6 +397,7 @@ environment type of 'managed-host." > (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 > diff --git a/guix/remote.scm b/guix/remote.scm > index 5fecd954e9..853029c54f 100644 > --- a/guix/remote.scm > +++ b/guix/remote.scm > @@ -24,6 +24,7 @@ > #:use-module (guix monads) > #:use-module (guix modules) > #:use-module (guix derivations) > + #:use-module (guix utils) > #:use-module (ssh popen) > #:use-module (srfi srfi-1) > #:use-module (ice-9 match) > diff --git a/guix/scripts/deploy.scm b/guix/scripts/deploy.scm > index ebc99e52cc..d16e7d7480 100644 > --- a/guix/scripts/deploy.scm > +++ b/guix/scripts/deploy.scm > @@ -28,6 +28,8 @@ > #:use-module (guix grafts) > #:use-module (ice-9 format) > #:use-module (srfi srfi-1) > + #:use-module (srfi srfi-34) > + #:use-module (srfi srfi-35) > #:use-module (srfi srfi-37) > #:export (guix-deploy)) > > @@ -91,8 +93,19 @@ Perform the deployment specified by FILE.\n")) > (with-store store > (set-build-options-from-command-line store opts) > (for-each (lambda (machine) > - (info (G_ "deploying to ~a...") (machine-display-name machine)) > + (info (G_ "deploying to ~a...~%") > + (machine-display-name machine)) > (parameterize ((%current-system (assq-ref opts 'system)) > (%graft? (assq-ref opts 'graft?))) > - (run-with-store store (deploy-machine machine)))) > + (guard (c ((message-condition? c) > + (report-error (G_ "failed to deploy ~a: '~a'~%") > + (machine-display-name machine) > + (condition-message c))) > + ((deploy-error? c) > + (when (deploy-error-should-roll-back c) > + (info (G_ "rolling back ~a...~%") > + (machine-display-name machine)) > + (run-with-store store (roll-back-machine machine))) > + (apply throw (deploy-error-captured-args c)))) > + (run-with-store store (deploy-machine machine))))) > machines))))