guix-devel/guix/scripts/offload.scm

740 lines
28 KiB
Scheme
Raw Blame History

This file contains invisible Unicode characters!

This file contains invisible Unicode characters that may be processed differently from what appears below. If your use case is intentional and legitimate, you can safely ignore this warning. Use the Escape button to reveal hidden characters.

;;; 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
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; 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 (ssh key)
#:use-module (ssh auth)
#:use-module (ssh session)
#:use-module (ssh channel)
#:use-module (guix config)
#:use-module (guix records)
#:use-module (guix store)
#:use-module (guix derivations)
#:use-module ((guix serialization)
#:select (nar-error? nar-error-file))
#: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 (ice-9 binary-ports)
#:export (build-machine
build-requirements
guix-offload))
;;; 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
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-openssh-private-key)))
(host-key build-machine-host-key) ; string
(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 '())))
(define-record-type* <build-requirements>
build-requirements make-build-requirements
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 (user-openssh-private-key)
"Return the user's default SSH private key, or #f if it could not be
determined."
(and=> (getenv "HOME")
(cut string-append <> "/.ssh/id_rsa")))
(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)))
module))
(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)
(save-module-excursion
(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)))
(x
(leave (_ "failed to load machine file '~a': ~s~%")
file args))))))
(define (host-key->type+key host-key)
"Destructure HOST-KEY, an OpenSSH host key string, and return two values:
its key type as a symbol, and the actual base64-encoded string."
(define (type->symbol type)
(and (string-prefix? "ssh-" type)
(string->symbol (string-drop type 4))))
(match (string-tokenize host-key)
((type key _)
(values (type->symbol type) key))
((type key)
(values (type->symbol type) key))))
(define (private-key-from-file* file)
"Like 'private-key-from-file', but raise an error that 'with-error-handling'
can interpret meaningfully."
(catch 'guile-ssh-error
(lambda ()
(private-key-from-file file))
(lambda (key proc str . rest)
(raise (condition
(&message (message (format #f (_ "failed to load SSH \
private key from '~a': ~a")
file str))))))))
(define (open-ssh-session machine)
"Open an SSH session for MACHINE and return it. Throw an error on failure."
(let ((private (private-key-from-file* (build-machine-private-key machine)))
(public (public-key-from-file
(string-append (build-machine-private-key machine)
".pub")))
(session (make-session #:user (build-machine-user machine)
#:host (build-machine-name machine)
#:port (build-machine-port machine)
#:timeout 5 ;seconds
;; #:log-verbosity 'protocol
#:identity (build-machine-private-key machine)
;; We need lightweight compression when
;; exchanging full archives.
#:compression "zlib"
#:compression-level 3)))
(connect! session)
;; Authenticate the server. XXX: Guile-SSH 0.10.1 doesn't know about
;; ed25519 keys and 'get-key-type' returns #f in that case.
(let-values (((server) (get-server-public-key session))
((type key) (host-key->type+key
(build-machine-host-key machine))))
(unless (and (or (not (get-key-type server))
(eq? (get-key-type server) type))
(string=? (public-key->string server) key))
;; Key mismatch: something's wrong. XXX: It could be that the server
;; provided its Ed25519 key when we where expecting its RSA key.
(leave (_ "server at '~a' returned host key '~a' of type '~a' \
instead of '~a' of type '~a'~%")
(build-machine-name machine)
(public-key->string server) (get-key-type server)
key type)))
(let ((auth (userauth-public-key! session private)))
(unless (eq? 'success auth)
(disconnect! session)
(leave (_ "SSH public key authentication failed for '~a': ~a~%")
(build-machine-name machine) (get-error session))))
session))
(define* (remote-pipe machine command
#:key (quote? #t))
"Run COMMAND (a list) on MACHINE, and return an open input/output port,
which is also an SSH channel. When QUOTE? is true, perform shell-quotation of
all the elements of COMMAND."
(define (shell-quote str)
;; Sort-of shell-quote STR so it can be passed as an argument to the
;; shell.
(with-output-to-string
(lambda ()
(write str))))
;; TODO: Use (ssh popen) instead.
(let* ((session (open-ssh-session machine))
(channel (make-channel session)))
(channel-open-session channel)
(channel-request-exec channel
(string-join (if quote?
(map shell-quote command)
command)))
channel))
;;;
;;; 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)
port))
(define (unlock-file lock)
"Unlock LOCK."
(fcntl-flock lock 'unlock)
(close-port lock)
#t)
(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)))
(dynamic-wind
(lambda ()
#t)
(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
context."
(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)
"w0")))
(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))
port)
(lambda args
;; PORT is already locked by another process.
(close-port port)
#f))))
(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
hook."
(let ((port (fdopen 4 "w0")))
;; Make sure file descriptor 4 isn't closed when PORT is GC'd.
(set-port-revealed! port 1)
port))
(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
`(begin
(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
"/gcroots/tmp")))
(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
`("guile" "-c" ,(object->string script)))))
(read-string pipe)
(let ((status (channel-get-exit-status pipe)))
(close-port 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
'register-gc-root'."
(define script
`(begin
(use-modules (guix config) (ice-9 ftw)
(srfi srfi-1) (srfi srfi-26))
(let ((root-directory (string-append %state-directory
"/gcroots/tmp")))
(false-if-exception
(delete-file
(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)))
roots)))))
(let ((pipe (remote-pipe machine
`("guile" "-c" ,(object->string script)))))
(read-string pipe)
(close-port 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
`("guix" "build"
"-r" ,%gc-root-file
,(format #f "--max-silent-time=~a"
max-silent-time)
,@(if build-timeout
(list (format #f "--timeout=~a"
build-timeout))
'())
,(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 ;; FIXME
)))
;; Make standard error visible.
(channel-set-stream! pipe 'stderr)
(let loop ((line (read-line pipe)))
(unless (eof-object? line)
(display line log-port)
(newline log-port)
(loop (read-line pipe))))
(let loop ((status (channel-get-exit-status pipe)))
(close-port pipe)
status)))
(define* (transfer-and-offload drv machine
#:key
(inputs '())
(outputs '())
(max-silent-time 3600)
build-timeout
print-build-trace?)
"Offload DRV to MACHINE. Prior to the actual offloading, transfer all of
INPUTS to MACHINE; if building DRV succeeds, retrieve all of OUTPUTS from
MACHINE."
(when (begin
(register-gc-root (derivation-file-name drv) machine)
(send-files (cons (derivation-file-name drv) inputs)
machine))
(let ((status (offload drv machine
#:print-build-trace? print-build-trace?
#:max-silent-time max-silent-time
#:build-timeout build-timeout)))
(if (zero? status)
(begin
(retrieve-files outputs machine)
(remove-gc-roots machine)
(format (current-error-port)
"done with offloaded '~a'~%"
(derivation-file-name drv)))
(begin
(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)
;; 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. Use 'head' as a
;; hack to make sure the remote end stops reading when we're done.
(let* ((pipe (remote-pipe machine
`("guix" "archive" "--missing")
#:quote? #f)))
(format pipe "~{~a~%~}" files)
(channel-send-eof pipe)
(string-tokenize (read-string pipe))))
(with-store store
(guard (c ((nix-protocol-error? c)
(warning (_ "failed to export files for '~a': ~s~%")
(build-machine-name machine)
c)
#f))
;; Compute the subset of FILES missing on MACHINE, and send them in
;; topologically sorted order so that they can actually be imported.
(let* ((files (missing-files (topologically-sorted store files)))
(pipe (remote-pipe machine
'("guix" "archive" "--import")
#:quote? #f)))
(format #t (_ "sending ~a store files to '~a'...~%")
(length files) (build-machine-name machine))
(export-paths store files pipe)
(channel-send-eof pipe)
;; Wait for the remote process to complete.
(let ((status (channel-get-exit-status pipe)))
(close pipe)
status)))))
(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
`("guix" "archive" "--export" ,@files)
#:quote? #f)))
(and pipe
(with-store store
(guard (c ((nix-protocol-error? c)
(warning (_ "failed to import files from '~a': ~s~%")
host c)
#f))
(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.
(restore-file-set pipe
#:log-port (current-error-port)
#:lock? #f)
(close-port 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 '("cat" "/proc/loadavg")))
(line (read-line pipe)))
(close-port pipe)
(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)
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
better."
(/ (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))))
machines))
(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))
(begin
;; BEST is overloaded, so try the next one.
(release-build-slot slot)
(loop others))))
(() #f)))))
(define* (process-request wants-local? system drv features
#:key
print-build-trace? (max-silent-time 3600)
build-timeout)
"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)
(build-machines))))
(match candidates
(()
;; We'll never be able to match REQS.
(display "# decline\n"))
((_ ...)
(let ((machine (choose-build-machine candidates)))
(if machine
(begin
;; 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'~%")
file)))))
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)
(with-nar-error-handling
(process-request (equal? (match:substring match 1) "1")
(match:substring match 2) ; system
(call-with-input-file
(match:substring match 3)
read-derivation)
(string-tokenize
(match:substring match 4) not-coma)
#:print-build-trace? print-build-trace?
#:max-silent-time max-silent-time
#:build-timeout build-timeout))))
(else
(leave (_ "invalid request line: ~s~%") line)))
(loop (read-line)))))))
(("--version")
(show-version-and-exit "guix offload"))
(("--help")
(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'.~%")
%machine-file)
(display (_ "
This tool is meant to be used internally by 'guix-daemon'.\n"))
(show-bug-report-information))
(x
(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