Mirror of GNU Guix
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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015, 2016 Ludovic Courtès <ludo@gnu.org>
;;; This file is part of GNU Guix.
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; GNU General Public License for more details.
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (guix scripts offload)
#:use-module (guix config)
#:use-module (guix records)
#:use-module (guix store)
#:use-module (guix derivations)
#:use-module (guix serialization)
#:use-module (guix nar)
#:use-module (guix utils)
#:use-module ((guix build syscalls) #:select (fcntl-flock))
#:use-module ((guix build utils) #:select (which mkdir-p))
#:use-module (guix ui)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-11)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:use-module (ice-9 popen)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 match)
#:use-module (ice-9 regex)
#:use-module (ice-9 format)
#:use-module (rnrs io ports)
#:export (build-machine
;;; Commentary:
;;; Attempt to offload builds to the machines listed in
;;; /etc/guix/machines.scm, transferring missing dependencies over SSH, and
;;; retrieving the build output(s) over SSH upon success.
;;; This command should not be used directly; instead, it is called on-demand
;;; by the daemon, unless it was started with '--no-build-hook' or a client
;;; inhibited build hooks.
;;; Code:
(define-record-type* <build-machine>
build-machine make-build-machine
(name build-machine-name) ; string
(port build-machine-port ; number
(default 22))
(system build-machine-system) ; string
(user build-machine-user) ; string
(private-key build-machine-private-key ; file name
(default (user-lsh-private-key)))
(parallel-builds build-machine-parallel-builds ; number
(default 1))
(speed build-machine-speed ; inexact real
(default 1.0))
(features build-machine-features ; list of strings
(default '()))
(ssh-options build-machine-ssh-options ; list of strings
(default '())))
(define-record-type* <build-requirements>
build-requirements make-build-requirements
(system build-requirements-system) ; string
(features build-requirements-features ; list of strings
(default '())))
(define %machine-file
;; File that lists machines available as build slaves.
(string-append %config-directory "/machines.scm"))
(define %lsh-command
(define %lshg-command
;; FIXME: 'lshg' fails to pass large amounts of data, see
;; <http://lists.lysator.liu.se/pipermail/lsh-bugs/2014q1/000639.html>.
(define (user-lsh-private-key)
"Return the user's default lsh private key, or #f if it could not be
(and=> (getenv "HOME")
(cut string-append <> "/.lsh/identity")))
(define %user-module
;; Module in which the machine description file is loaded.
(let ((module (make-fresh-user-module)))
(module-use! module (resolve-interface '(guix scripts offload)))
(define* (build-machines #:optional (file %machine-file))
"Read the list of build machines from FILE and return it."
(catch #t
(lambda ()
;; Avoid ABI incompatibility with the <build-machine> record.
(set! %fresh-auto-compile #t)
(lambda ()
(set-current-module %user-module)
(primitive-load file))))
(lambda args
(match args
(('system-error . rest)
(let ((err (system-error-errno args)))
;; Silently ignore missing file since this is a common case.
(if (= ENOENT err)
(leave (_ "failed to open machine file '~a': ~a~%")
file (strerror err)))))
(('syntax-error proc message properties form . rest)
(let ((loc (source-properties->location properties)))
(leave (_ "~a: ~a~%")
(location->string loc) message)))
(leave (_ "failed to load machine file '~a': ~s~%")
file args))))))
;;; FIXME: The idea was to open the connection to MACHINE once for all, but
;;; lshg is currently non-functional.
;; (define (open-ssh-gateway machine)
;; "Initiate an SSH connection gateway to MACHINE, and return the PID of the
;; running lsh gateway upon success, or #f on failure."
;; (catch 'system-error
;; (lambda ()
;; (let* ((port (open-pipe* OPEN_READ %lsh-command
;; "-l" (build-machine-user machine)
;; "-i" (build-machine-private-key machine)
;; ;; XXX: With lsh 2.1, passing '--write-pid'
;; ;; last causes the PID not to be printed.
;; "--write-pid" "--gateway" "--background"
;; (build-machine-name machine)))
;; (line (read-line port))
;; (status (close-pipe port)))
;; (if (zero? status)
;; (let ((pid (string->number line)))
;; (if (integer? pid)
;; pid
;; (begin
;; (warning (_ "'~a' did not write its PID on stdout: ~s~%")
;; %lsh-command line)
;; #f)))
;; (begin
;; (warning (_ "failed to initiate SSH connection to '~a':\
;; '~a' exited with ~a~%")
;; (build-machine-name machine)
;; %lsh-command
;; (status:exit-val status))
;; #f))))
;; (lambda args
;; (leave (_ "failed to execute '~a': ~a~%")
;; %lsh-command (strerror (system-error-errno args))))))
(define-syntax with-error-to-port
(syntax-rules ()
((_ port exp0 exp ...)
(let ((new port)
(old (current-error-port)))
(lambda ()
(set-current-error-port new))
(lambda ()
exp0 exp ...)
(lambda ()
(set-current-error-port old)))))))
(define* (remote-pipe machine mode command
#:key (error-port (current-error-port)) (quote? #t))
"Run COMMAND (a string list) on MACHINE, assuming an lsh gateway has been
set up. When QUOTE? is true, perform shell-quotation of all the elements of
COMMAND. Return either a pipe opened with MODE, or #f if the lsh client could
not be started."
(define (shell-quote str)
;; Sort-of shell-quote STR so it can be passed as an argument to the
;; shell.
(lambda ()
(write str))))
;; Let the child inherit ERROR-PORT.
(with-error-to-port error-port
(apply open-pipe* mode %lshg-command
"-l" (build-machine-user machine)
"-p" (number->string (build-machine-port machine))
;; XXX: Remove '-i' when %LSHG-COMMAND really is lshg.
"-i" (build-machine-private-key machine)
(append (build-machine-ssh-options machine)
(list (build-machine-name machine))
(if quote?
(map shell-quote command)
;;; Synchronization.
(define (lock-file file)
"Wait and acquire an exclusive lock on FILE. Return an open port."
(mkdir-p (dirname file))
(let ((port (open-file file "w0")))
(fcntl-flock port 'write-lock)
(define (unlock-file lock)
"Unlock LOCK."
(fcntl-flock lock 'unlock)
(close-port lock)
(define-syntax-rule (with-file-lock file exp ...)
"Wait to acquire a lock on FILE and evaluate EXP in that context."
(let ((port (lock-file file)))
(lambda ()
(lambda ()
exp ...)
(lambda ()
(unlock-file port)))))
(define-syntax-rule (with-machine-lock machine hint exp ...)
"Wait to acquire MACHINE's exclusive lock for HINT, and evaluate EXP in that
(with-file-lock (machine-lock-file machine hint)
exp ...))
(define (machine-slot-file machine slot)
"Return the file name of MACHINE's file for SLOT."
;; For each machine we have a bunch of files representing each build slot.
;; When choosing a build machine, we attempt to get an exclusive lock on one
;; of these; if we fail, that means all the build slots are already taken.
;; Inspired by Nix's build-remote.pl.
(string-append (string-append %state-directory "/offload/"
(build-machine-name machine)
"/" (number->string slot))))
(define (acquire-build-slot machine)
"Attempt to acquire a build slot on MACHINE. Return the port representing
the slot, or #f if none is available.
This mechanism allows us to set a hard limit on the number of simultaneous
connections allowed to MACHINE."
(mkdir-p (dirname (machine-slot-file machine 0)))
(with-machine-lock machine 'slots
(any (lambda (slot)
(let ((port (open-file (machine-slot-file machine slot)
(catch 'flock-error
(lambda ()
(fcntl-flock port 'write-lock #:wait? #f)
;; Got it!
(format (current-error-port)
"process ~a acquired build slot '~a'~%"
(getpid) (port-filename port))
(lambda args
;; PORT is already locked by another process.
(close-port port)
(iota (build-machine-parallel-builds machine)))))
(define (release-build-slot slot)
"Release SLOT, a build slot as returned as by 'acquire-build-slot'."
(close-port slot))
;;; Offloading.
(define (build-log-port)
"Return the default port where build logs should be sent. The default is
file descriptor 4, which is open by the daemon before running the offload
(let ((port (fdopen 4 "w0")))
;; Make sure file descriptor 4 isn't closed when PORT is GC'd.
(set-port-revealed! port 1)
(define %gc-root-file
;; File name of the temporary GC root we install.
(format #f "offload-~a-~a" (gethostname) (getpid)))
(define (register-gc-root file machine)
"Mark FILE, a store item, as a garbage collector root on MACHINE."
(define script
(use-modules (guix config))
;; Note: we can't use 'add-indirect-root' because dangling links under
;; gcroots/auto are automatically deleted by the GC. This strategy
;; doesn't have this problem, but it requires write access to that
;; directory.
(let ((root-directory (string-append %state-directory
(catch 'system-error
(lambda ()
(mkdir root-directory))
(lambda args
(unless (= EEXIST (system-error-errno args))
(error "failed to create remote GC root directory"
root-directory (system-error-errno args)))))
(catch 'system-error
(lambda ()
(symlink ,file
(string-append root-directory "/" ,%gc-root-file)))
(lambda args
;; If FILE already exists, we can assume that either it's a stale
;; reference (which is fine), or another process is already
;; building the derivation represented by FILE (which is fine
;; too.) Thus, do nothing in that case.
(unless (= EEXIST (system-error-errno args))
(apply throw args)))))))
(let ((pipe (remote-pipe machine OPEN_READ
`("guile" "-c" ,(object->string script)))))
(get-string-all pipe)
(let ((status (close-pipe pipe)))
(unless (zero? status)
;; Better be safe than sorry: if we ignore the error here, then FILE
;; may be GC'd just before we start using it.
(leave (_ "failed to register GC root for '~a' on '~a' (status: ~a)~%")
file (build-machine-name machine) status)))))
(define (remove-gc-roots machine)
"Remove from MACHINE the GC roots previously installed with
(define script
(use-modules (guix config) (ice-9 ftw)
(srfi srfi-1) (srfi srfi-26))
(let ((root-directory (string-append %state-directory
(string-append root-directory "/" ,%gc-root-file)))
;; These ones were created with 'guix build -r' (there can be more
;; than one in case of multiple-output derivations.)
(let ((roots (filter (cut string-prefix? ,%gc-root-file <>)
(scandir "."))))
(for-each (lambda (file)
(false-if-exception (delete-file file)))
(let ((pipe (remote-pipe machine OPEN_READ
`("guile" "-c" ,(object->string script)))))
(get-string-all pipe)
(close-pipe pipe)))
(define* (offload drv machine
#:key print-build-trace? (max-silent-time 3600)
build-timeout (log-port (build-log-port)))
"Perform DRV on MACHINE, assuming DRV and its prerequisites are available
there, and write the build log to LOG-PORT. Return the exit status."
(format (current-error-port) "offloading '~a' to '~a'...~%"
(derivation-file-name drv) (build-machine-name machine))
(format (current-error-port) "@ build-remote ~a ~a~%"
(derivation-file-name drv) (build-machine-name machine))
;; Normally DRV has already been protected from GC when it was transferred.
;; The '-r' flag below prevents the build result from being GC'd.
(let ((pipe (remote-pipe machine OPEN_READ
`("guix" "build"
"-r" ,%gc-root-file
,(format #f "--max-silent-time=~a"
,@(if build-timeout
(list (format #f "--timeout=~a"
,(derivation-file-name drv))
;; Since 'guix build' writes the build log to its
;; stderr, everything will go directly to LOG-PORT.
#:error-port log-port)))
(let loop ((line (read-line pipe)))
(unless (eof-object? line)
(display line log-port)
(newline log-port)
(loop (read-line pipe))))
(close-pipe pipe)))
(define* (transfer-and-offload drv machine
(inputs '())
(outputs '())
(max-silent-time 3600)
"Offload DRV to MACHINE. Prior to the actual offloading, transfer all of
INPUTS to MACHINE; if building DRV succeeds, retrieve all of OUTPUTS from
(when (begin
(register-gc-root (derivation-file-name drv) machine)
(send-files (cons (derivation-file-name drv) inputs)
(let ((status (offload drv machine
#:print-build-trace? print-build-trace?
#:max-silent-time max-silent-time
#:build-timeout build-timeout)))
(if (zero? status)
(retrieve-files outputs machine)
(remove-gc-roots machine)
(format (current-error-port)
"done with offloaded '~a'~%"
(derivation-file-name drv)))
(remove-gc-roots machine)
(format (current-error-port)
"derivation '~a' offloaded to '~a' failed \
with exit code ~a~%"
(derivation-file-name drv)
(build-machine-name machine)
(status:exit-val status))
;; Use exit code 100 for a permanent build failure. The daemon
;; interprets other non-zero codes as transient build failures.
(primitive-exit 100))))))
(define (send-files files machine)
"Send the subset of FILES that's missing to MACHINE's store. Return #t on
success, #f otherwise."
(define (missing-files files)
;; Return the subset of FILES not already on MACHINE.
(let*-values (((files)
(format #f "~{~a~%~}" files))
((missing pids)
(append (list (which %lshg-command)
"-l" (build-machine-user machine)
"-p" (number->string
(build-machine-port machine))
"-i" (build-machine-private-key machine))
(build-machine-ssh-options machine)
(cons (build-machine-name machine)
'("guix" "archive" "--missing")))
(open-input-string files)))
(get-string-all missing)))
(for-each waitpid pids)
(string-tokenize result)))
(with-store store
(guard (c ((nix-protocol-error? c)
(warning (_ "failed to export files for '~a': ~s~%")
(build-machine-name machine)
;; Compute the subset of FILES missing on MACHINE, and send them in
;; topologically sorted order so that they can actually be imported.
;; To reduce load on the machine that's offloading (since it's typically
;; already quite busy, see hydra.gnu.org), compress with gzip rather
;; than xz: For a compression ratio 2 times larger, it is 20 times
;; faster.
(let* ((files (missing-files (topologically-sorted store files)))
(pipe (remote-pipe machine OPEN_WRITE
'("gzip" "-dc" "|"
"guix" "archive" "--import")
#:quote? #f)))
(format #t (_ "sending ~a store files to '~a'...~%")
(length files) (build-machine-name machine))
(call-with-compressed-output-port 'gzip pipe
(lambda (compressed)
(catch 'system-error
(lambda ()
(export-paths store files compressed))
(lambda args
(warning (_ "failed while exporting files to '~a': ~a~%")
(build-machine-name machine)
(strerror (system-error-errno args))))))
#:options '("--fast"))
;; Wait for the 'lsh' process to complete.
(zero? (close-pipe pipe))))))
(define (retrieve-files files machine)
"Retrieve FILES from MACHINE's store, and import them."
(define host
(build-machine-name machine))
(let ((pipe (remote-pipe machine OPEN_READ
`("guix" "archive" "--export" ,@files
"|" "xz" "-c")
#:quote? #f)))
(and pipe
(with-store store
(guard (c ((nix-protocol-error? c)
(warning (_ "failed to import files from '~a': ~s~%")
host c)
(format (current-error-port) "retrieving ~a files from '~a'...~%"
(length files) host)
;; We cannot use the 'import-paths' RPC here because we already
;; hold the locks for FILES.
(call-with-decompressed-port 'xz pipe
(lambda (decompressed)
(restore-file-set decompressed
#:log-port (current-error-port)
#:lock? #f)))
;; Wait for the 'lsh' process to complete.
(zero? (close-pipe pipe)))))))
;;; Scheduling.
(define (machine-matches? machine requirements)
"Return #t if MACHINE matches REQUIREMENTS."
(and (string=? (build-requirements-system requirements)
(build-machine-system machine))
(lset<= string=?
(build-requirements-features requirements)
(build-machine-features machine))))
(define (machine-load machine)
"Return the load of MACHINE, divided by the number of parallel builds
allowed on MACHINE."
(let* ((pipe (remote-pipe machine OPEN_READ `("cat" "/proc/loadavg")))
(line (read-line pipe))
(status (close-pipe pipe)))
(unless (eqv? 0 (status:exit-val status))
(warning (_ "failed to obtain load of '~a': SSH client exited with ~a~%")
(build-machine-name machine)
(status:exit-val status)))
(if (eof-object? line)
+inf.0 ;MACHINE does not respond, so assume it is infinitely loaded
(match (string-tokenize line)
((one five fifteen . _)
(let* ((raw (string->number five))
(jobs (build-machine-parallel-builds machine))
(normalized (/ raw jobs)))
(format (current-error-port) "load on machine '~a' is ~s\
(normalized: ~s)~%"
(build-machine-name machine) raw normalized)
+inf.0))))) ;something's fishy about MACHINE, so avoid it
(define (machine-power-factor m)
"Return a factor that aggregates the speed and load of M. The higher the
(/ (build-machine-speed m)
(+ 1 (machine-load m))))
(define (machine-less-loaded-or-faster? m1 m2)
"Return #t if M1 is either less loaded or faster than M2. (This relation
defines a total order on machines.)"
(> (machine-power-factor m1) (machine-power-factor m2)))
(define (machine-lock-file machine hint)
"Return the name of MACHINE's lock file for HINT."
(string-append %state-directory "/offload/"
(build-machine-name machine)
"." (symbol->string hint) ".lock"))
(define (machine-choice-lock-file)
"Return the name of the file used as a lock when choosing a build machine."
(string-append %state-directory "/offload/machine-choice.lock"))
(define %slots
;; List of acquired build slots (open ports).
(define (choose-build-machine machines)
"Return the best machine among MACHINES, or #f."
;; Proceed like this:
;; 1. Acquire the global machine-choice lock.
;; 2. For all MACHINES, attempt to acquire a build slot, and filter out
;; those machines for which we failed.
;; 3. Choose the best machine among those that are left.
;; 4. Release the previously-acquired build slots of the other machines.
;; 5. Release the global machine-choice lock.
(with-file-lock (machine-choice-lock-file)
(define machines+slots
(filter-map (lambda (machine)
(let ((slot (acquire-build-slot machine)))
(and slot (list machine slot))))
(define (undecorate pred)
(lambda (a b)
(match a
((machine1 slot1)
(match b
((machine2 slot2)
(pred machine1 machine2)))))))
(let loop ((machines+slots
(sort machines+slots
(undecorate machine-less-loaded-or-faster?))))
(match machines+slots
(((best slot) others ...)
;; Return the best machine unless it's already overloaded.
(if (< (machine-load best) 2.)
(match others
(((machines slots) ...)
;; Release slots from the uninteresting machines.
(for-each release-build-slot slots)
;; Prevent SLOT from being GC'd.
(set! %slots (cons slot %slots))
;; BEST is overloaded, so try the next one.
(release-build-slot slot)
(loop others))))
(() #f)))))
(define* (process-request wants-local? system drv features
print-build-trace? (max-silent-time 3600)
"Process a request to build DRV."
(let* ((local? (and wants-local? (string=? system (%current-system))))
(reqs (build-requirements
(system system)
(features features)))
(candidates (filter (cut machine-matches? <> reqs)
(match candidates
;; We'll never be able to match REQS.
(display "# decline\n"))
((_ ...)
(let ((machine (choose-build-machine candidates)))
(if machine
;; Offload DRV to MACHINE.
(display "# accept\n")
(let ((inputs (string-tokenize (read-line)))
(outputs (string-tokenize (read-line))))
(transfer-and-offload drv machine
#:inputs inputs
#:outputs outputs
#:max-silent-time max-silent-time
#:build-timeout build-timeout
#:print-build-trace? print-build-trace?)))
;; Not now, all the machines are busy.
(display "# postpone\n")))))))
(define-syntax-rule (with-nar-error-handling body ...)
"Execute BODY with any &nar-error suitably reported to the user."
(guard (c ((nar-error? c)
(let ((file (nar-error-file c)))
(if (condition-has-type? c &message)
(leave (_ "while importing file '~a': ~a~%")
file (gettext (condition-message c)))
(leave (_ "failed to import file '~a'~%")
body ...))
;;; Entry point.
(define (guix-offload . args)
(define request-line-rx
;; The request format. See 'tryBuildHook' method in build.cc.
(make-regexp "([01]) ([a-z0-9_-]+) (/[[:graph:]]+.drv) ([[:graph:]]*)"))
(define not-coma
(char-set-complement (char-set #\,)))
;; Make sure $HOME really corresponds to the current user. This is
;; necessary since lsh uses that to determine the location of the yarrow
;; seed file, and fails if it's owned by someone else.
(and=> (passwd:dir (getpw (getuid)))
(cut setenv "HOME" <>))
(match args
((system max-silent-time print-build-trace? build-timeout)
(let ((max-silent-time (string->number max-silent-time))
(build-timeout (string->number build-timeout))
(print-build-trace? (string=? print-build-trace? "1")))
(parameterize ((%current-system system))
(let loop ((line (read-line)))
(unless (eof-object? line)
(cond ((regexp-exec request-line-rx line)
(lambda (match)
(process-request (equal? (match:substring match 1) "1")
(match:substring match 2) ; system
(match:substring match 3)
(match:substring match 4) not-coma)
#:print-build-trace? print-build-trace?
#:max-silent-time max-silent-time
#:build-timeout build-timeout))))
(leave (_ "invalid request line: ~s~%") line)))
(loop (read-line)))))))
(show-version-and-exit "guix offload"))
(format #t (_ "Usage: guix offload SYSTEM PRINT-BUILD-TRACE
Process build offload requests written on the standard input, possibly
offloading builds to the machines listed in '~a'.~%")
(display (_ "
This tool is meant to be used internally by 'guix-daemon'.\n"))
(leave (_ "invalid arguments: ~{~s ~}~%") x))))
;;; Local Variables:
;;; eval: (put 'with-machine-lock 'scheme-indent-function 2)
;;; eval: (put 'with-file-lock 'scheme-indent-function 1)
;;; eval: (put 'with-error-to-port 'scheme-indent-function 1)
;;; End:
;;; offload.scm ends here