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authorLudovic Courtès <ludo@gnu.org>2020-03-20 12:08:10 +0100
committerLudovic Courtès <ludo@gnu.org>2020-03-23 10:48:17 +0100
commitea6e2299b40c6fbd9749563c52a2d77698bd9337 (patch)
tree71e1e8f02277b8f905a82d2110d93de49dc7bba4 /gnu/machine
parent8f53d73493a2949e2db28cd7d689a690b2d9479a (diff)
downloadguix-ea6e2299b40c6fbd9749563c52a2d77698bd9337.tar
guix-ea6e2299b40c6fbd9749563c52a2d77698bd9337.tar.gz
machine: ssh: Make sanity checks in a single round trip.
* gnu/machine/ssh.scm (<remote-assertion>): New record type. (remote-let): New macro. (machine-check-file-system-availability): Rewrite to use 'remote-let' instead of 'mlet' and 'machine-remote-eval'. (machine-check-initrd-modules): Likewise. (machine-check-building-for-appropriate-system): Make non-monadic. (check-deployment-sanity): Rewrite to gather all the assertions as a single gexp and pass it to 'machine-remote-eval'.
Diffstat (limited to 'gnu/machine')
-rw-r--r--gnu/machine/ssh.scm142
1 files changed, 83 insertions, 59 deletions
diff --git a/gnu/machine/ssh.scm b/gnu/machine/ssh.scm
index 6374373e22..85ecbb6d14 100644
--- a/gnu/machine/ssh.scm
+++ b/gnu/machine/ssh.scm
@@ -1,5 +1,6 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019 Jakob L. Kreuze <zerodaysfordays@sdf.org>
+;;; Copyright © 2020 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -39,6 +40,7 @@
#:use-module (ice-9 match)
#:use-module (ice-9 textual-ports)
#:use-module (srfi srfi-1)
+ #:use-module (srfi srfi-9)
#:use-module (srfi srfi-19)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
@@ -142,9 +144,24 @@ an environment type of 'managed-host."
;;; Safety checks.
;;;
+;; Assertion to be executed remotely. This abstraction exists to allow us to
+;; gather a list of expressions to be evaluated and eventually evaluate them
+;; all at once instead of one by one. (This is pretty much a monad.)
+(define-record-type <remote-assertion>
+ (remote-assertion exp proc)
+ remote-assertion?
+ (exp remote-assertion-expression)
+ (proc remote-assertion-procedure))
+
+(define-syntax-rule (remote-let ((var exp)) body ...)
+ "Return a <remote-assertion> that binds VAR to the result of evaluating EXP,
+a gexp, remotely, and evaluate BODY in that context."
+ (remote-assertion exp (lambda (var) body ...)))
+
(define (machine-check-file-system-availability machine)
- "Raise a '&message' error condition if any of the file-systems specified in
-MACHINE's 'system' declaration do not exist on the machine."
+ "Return a list of <remote-assertion> that raise a '&message' error condition
+if any of the file-systems specified in MACHINE's 'system' declaration do not
+exist on the machine."
(define file-systems
(filter (lambda (fs)
(and (file-system-mount? fs)
@@ -154,22 +171,18 @@ MACHINE's 'system' declaration do not exist on the machine."
(operating-system-file-systems (machine-operating-system machine))))
(define (check-literal-file-system fs)
- (define remote-exp
- #~(catch 'system-error
- (lambda ()
- (stat #$(file-system-device fs))
- #t)
- (lambda args
- (system-error-errno args))))
-
- (mlet %store-monad ((errno (machine-remote-eval machine remote-exp)))
+ (remote-let ((errno #~(catch 'system-error
+ (lambda ()
+ (stat #$(file-system-device fs))
+ #t)
+ (lambda args
+ (system-error-errno args)))))
(when (number? errno)
(raise (condition
(&message
(message (format #f (G_ "device '~a' not found: ~a")
(file-system-device fs)
- (strerror errno)))))))
- (return #t)))
+ (strerror errno)))))))))
(define (check-labeled-file-system fs)
(define remote-exp
@@ -180,14 +193,13 @@ MACHINE's 'system' declaration do not exist on the machine."
(find-partition-by-label #$(file-system-label->string
(file-system-device fs))))))
- (mlet %store-monad ((result (machine-remote-eval machine remote-exp)))
+ (remote-let ((result remote-exp))
(unless result
(raise (condition
(&message
(message (format #f (G_ "no file system with label '~a'")
(file-system-label->string
- (file-system-device fs))))))))
- (return #t)))
+ (file-system-device fs))))))))))
(define (check-uuid-file-system fs)
(define remote-exp
@@ -203,31 +215,30 @@ MACHINE's 'system' declaration do not exist on the machine."
(find-partition-by-uuid uuid))))
- (mlet %store-monad ((result (machine-remote-eval machine remote-exp)))
+ (remote-let ((result remote-exp))
(unless result
(raise (condition
(&message
(message (format #f (G_ "no file system with UUID '~a'")
- (uuid->string (file-system-device fs))))))))
- (return #t)))
-
- (mbegin %store-monad
- (mapm %store-monad check-literal-file-system
- (filter (lambda (fs)
- (string? (file-system-device fs)))
- file-systems))
- (mapm %store-monad check-labeled-file-system
- (filter (lambda (fs)
- (file-system-label? (file-system-device fs)))
- file-systems))
- (mapm %store-monad check-uuid-file-system
- (filter (lambda (fs)
- (uuid? (file-system-device fs)))
- file-systems))))
+ (uuid->string (file-system-device fs))))))))))
+
+ (append (map check-literal-file-system
+ (filter (lambda (fs)
+ (string? (file-system-device fs)))
+ file-systems))
+ (map check-labeled-file-system
+ (filter (lambda (fs)
+ (file-system-label? (file-system-device fs)))
+ file-systems))
+ (map check-uuid-file-system
+ (filter (lambda (fs)
+ (uuid? (file-system-device fs)))
+ file-systems))))
(define (machine-check-initrd-modules machine)
- "Raise a '&message' error condition if any of the modules needed by
-'needed-for-boot' file systems in MACHINE are not available in the initrd."
+ "Return a list of <remote-assertion> that raise a '&message' error condition
+if any of the modules needed by 'needed-for-boot' file systems in MACHINE are
+not available in the initrd."
(define file-systems
(filter file-system-needed-for-boot?
(operating-system-file-systems (machine-operating-system machine))))
@@ -255,20 +266,16 @@ MACHINE's 'system' declaration do not exist on the machine."
(missing-modules dev '#$(operating-system-initrd-modules
(machine-operating-system machine)))))))
- (mlet %store-monad ((missing (machine-remote-eval machine remote-exp)))
- (return (list fs missing))))
-
- (mlet %store-monad ((device (mapm %store-monad missing-modules file-systems)))
- (for-each (match-lambda
- ((fs missing)
- (unless (null? missing)
- (raise (condition
- (&message
- (message (format #f (G_ "~a missing modules ~{ ~a~}~%")
- (file-system-device fs)
- missing))))))))
- device)
- (return #t)))
+
+ (remote-let ((missing remote-exp))
+ (unless (null? missing)
+ (raise (condition
+ (&message
+ (message (format #f (G_ "~a missing modules ~{ ~a~}~%")
+ (file-system-device fs)
+ missing))))))))
+
+ (map missing-modules file-systems))
(define (machine-check-building-for-appropriate-system machine)
"Raise a '&message' error condition if MACHINE is configured to be built
@@ -280,21 +287,38 @@ by MACHINE."
(not (string= system (machine-ssh-configuration-system config))))
(raise (condition
(&message
- (message (format #f (G_ "incorrect target system \
-('~a' was given, while the system reports that it is '~a')~%")
+ (message (format #f (G_ "incorrect target system\
+ ('~a' was given, while the system reports that it is '~a')~%")
(machine-ssh-configuration-system config)
- system)))))))
- (with-monad %store-monad (return #t)))
+ system))))))))
(define (check-deployment-sanity machine)
"Raise a '&message' error condition if it is clear that deploying MACHINE's
'system' declaration would fail."
- ;; Order is important here -- an incorrect value for 'system' will cause
- ;; invocations of 'remote-eval' to fail.
- (mbegin %store-monad
- (machine-check-building-for-appropriate-system machine)
- (machine-check-file-system-availability machine)
- (machine-check-initrd-modules machine)))
+ (define assertions
+ (append (machine-check-file-system-availability machine)
+ (machine-check-initrd-modules machine)))
+
+ (define aggregate-exp
+ ;; Gather all the expressions so that a single round-trip is enough to
+ ;; evaluate all the ASSERTIONS remotely.
+ #~(map (lambda (file)
+ (false-if-exception (primitive-load file)))
+ '#$(map (lambda (assertion)
+ (scheme-file "remote-assertion.scm"
+ (remote-assertion-expression assertion)))
+ assertions)))
+
+ ;; First check MACHINE's system type--an incorrect value for 'system' would
+ ;; cause subsequent invocations of 'remote-eval' to fail.
+ (machine-check-building-for-appropriate-system machine)
+
+ (mlet %store-monad ((values (machine-remote-eval machine aggregate-exp)))
+ (for-each (lambda (proc value)
+ (proc value))
+ (map remote-assertion-procedure assertions)
+ values)
+ (return #t)))
;;;