1 ;;; GNU Guix --- Functional package management for GNU
2 ;;; Copyright © 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
4 ;;; This file is part of GNU Guix.
6 ;;; GNU Guix is free software; you can redistribute it and/or modify it
7 ;;; under the terms of the GNU General Public License as published by
8 ;;; the Free Software Foundation; either version 3 of the License, or (at
9 ;;; your option) any later version.
11 ;;; GNU Guix is distributed in the hope that it will be useful, but
12 ;;; WITHOUT ANY WARRANTY; without even the implied warranty of
13 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 ;;; GNU General Public License for more details.
16 ;;; You should have received a copy of the GNU General Public License
17 ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
19 (define-module (guix ssh)
20 #:use-module (guix store)
21 #:use-module (guix inferior)
22 #:use-module (guix i18n)
23 #:use-module ((guix utils) #:select (&fix-hint))
24 #:use-module (gcrypt pk-crypto)
25 #:use-module (ssh session)
26 #:use-module (ssh auth)
27 #:use-module (ssh key)
28 #:use-module (ssh channel)
29 #:use-module (ssh popen)
30 #:use-module (ssh session)
31 #:use-module (srfi srfi-1)
32 #:use-module (srfi srfi-11)
33 #:use-module (srfi srfi-26)
34 #:use-module (srfi srfi-34)
35 #:use-module (srfi srfi-35)
36 #:use-module (ice-9 match)
37 #:use-module (ice-9 format)
38 #:use-module (ice-9 binary-ports)
39 #:export (open-ssh-session
42 connect-to-remote-daemon
44 remote-authorize-signing-key
55 ;;; This module provides tools to support communication with remote stores
56 ;;; over SSH, using Guile-SSH.
61 "zlib@openssh.com,zlib")
63 (define* (open-ssh-session host #:key user port identity
64 (compression %compression)
66 "Open an SSH session for HOST and return it. IDENTITY specifies the file
67 name of a private key to use for authenticating with the host. When USER,
68 PORT, or IDENTITY are #f, use default values or whatever '~/.ssh/config'
69 specifies; otherwise use them. Install TIMEOUT as the maximum time in seconds
70 after which a read or write operation on a channel of the returned session is
71 considered as failing.
73 Throw an error on failure."
74 (let ((session (make-session #:user user
79 ;; #:log-verbosity 'protocol
81 ;; We need lightweight compression when
82 ;; exchanging full archives.
83 #:compression compression
84 #:compression-level 3)))
86 ;; Honor ~/.ssh/config.
87 (session-parse-config! session)
89 (match (connect! session)
91 ;; Use public key authentication, via the SSH agent if it's available.
92 (match (userauth-public-key/auto! session)
94 (session-set! session 'timeout timeout)
100 (message (format #f (G_ "SSH authentication failed for '~a': ~a~%")
101 host (get-error session)))))))))
103 ;; Connection failed or timeout expired.
106 (message (format #f (G_ "SSH connection to '~a' failed: ~a~%")
107 host (get-error session))))))))))
109 (define* (remote-inferior session #:optional become-command)
110 "Return a remote inferior for the given SESSION. If BECOME-COMMAND is
111 given, use that to invoke the remote Guile REPL."
112 (let* ((repl-command (append (or become-command '())
113 '("guix" "repl" "-t" "machine")))
114 (pipe (apply open-remote-pipe* session OPEN_BOTH repl-command)))
115 (when (eof-object? (peek-char pipe))
116 (let ((status (channel-get-exit-status pipe)))
120 (message (format #f (G_ "remote command '~{~a~^ ~}' failed \
122 repl-command status)))))))
123 (port->inferior pipe)))
125 (define* (inferior-remote-eval exp session #:optional become-command)
126 "Evaluate EXP in a new inferior running in SESSION, and close the inferior
127 right away. If BECOME-COMMAND is given, use that to invoke the remote Guile
129 (let ((inferior (remote-inferior session become-command)))
133 (inferior-eval exp inferior))
135 ;; Close INFERIOR right away to prevent finalization from happening in
136 ;; another thread at the wrong time (see
137 ;; <https://bugs.gnu.org/26976>.)
138 (close-inferior inferior)))))
140 (define* (remote-daemon-channel session
143 "/var/guix/daemon-socket/socket"))
144 "Return an input/output port (an SSH channel) to the daemon at SESSION."
146 ;; Code run in SESSION to redirect the remote process' stdin/stdout to the
147 ;; daemon's socket, à la socat. The SSH protocol supports forwarding to
148 ;; Unix-domain sockets but libssh doesn't have an API for that, hence this
151 (use-modules (ice-9 match) (rnrs io ports)
154 (let ((sock (socket AF_UNIX SOCK_STREAM 0))
155 (stdin (current-input-port))
156 (stdout (current-output-port))
157 (select* (lambda (read write except)
158 ;; This is a workaround for
159 ;; <https://bugs.gnu.org/30365> in Guile < 2.2.4:
160 ;; since 'select' sometimes returns non-empty sets for
161 ;; no good reason, call 'select' a second time with a
162 ;; zero timeout to filter out incorrect replies.
163 (match (select read write except)
165 (select read write except 0))))))
166 (setvbuf stdout 'none)
168 ;; Use buffered ports so that 'get-bytevector-some' returns up to the
169 ;; whole buffer like read(2) would--see <https://bugs.gnu.org/30066>.
170 (setvbuf stdin 'block 65536)
171 (setvbuf sock 'block 65536)
173 (connect sock AF_UNIX ,socket-name)
176 (match (select* (list stdin sock) '() '())
178 (when (memq stdin reads)
179 (match (get-bytevector-some stdin)
183 (put-bytevector sock bv)
184 (force-output sock))))
185 (when (memq sock reads)
186 (match (get-bytevector-some sock)
190 (put-bytevector stdout bv))))
193 (primitive-exit 1)))))))
195 (open-remote-pipe* session OPEN_BOTH
196 ;; Sort-of shell-quote REDIRECT.
199 (object->string redirect))))
201 (define* (connect-to-remote-daemon session
204 "/var/guix/daemon-socket/socket"))
205 "Connect to the remote build daemon listening on SOCKET-NAME over SESSION,
206 an SSH session. Return a <store-connection> object."
207 (open-connection #:port (remote-daemon-channel session socket-name)))
210 (define (store-import-channel session)
211 "Return an output port to which archives to be exported to SESSION's store
213 ;; Using the 'import-paths' RPC on a remote store would be slow because it
214 ;; makes a round trip every time 32 KiB have been transferred. This
215 ;; procedure instead opens a separate channel to use the remote
216 ;; 'import-paths' procedure, which consumes all the data in a single round
217 ;; trip. This optimizes the successful case at the expense of error
218 ;; conditions: errors can only be reported once all the input has been
222 (use-modules (guix) (srfi srfi-34)
223 (rnrs io ports) (rnrs bytevectors))
225 (define (consume-input port)
226 (let ((bv (make-bytevector 32768)))
228 (let ((n (get-bytevector-n! port bv 0
229 (bytevector-length bv))))
230 (unless (eof-object? n)
233 ;; Upon completion, write an sexp that denotes the status.
237 (guard (c ((nix-protocol-error? c)
238 ;; Consume all the input since the only time we can
239 ;; report the error is after everything has been
241 (consume-input (current-input-port))
242 (list 'protocol-error (nix-protocol-error-message c))))
244 (setvbuf (current-input-port) 'none)
245 (import-paths store (current-input-port))
248 (cons 'error args))))))
250 (open-remote-pipe session
253 ,(object->string (object->string import))))
256 (define* (store-export-channel session files
258 "Return an input port from which an export of FILES from SESSION's store can
259 be read. When RECURSIVE? is true, the closure of FILES is exported."
260 ;; Same as above: this is more efficient than calling 'export-paths' on a
264 (eval-when (load expand eval)
265 (unless (resolve-module '(guix) #:ensure #f)
266 (write `(module-error))
269 (use-modules (guix) (srfi srfi-1)
270 (srfi srfi-26) (srfi srfi-34))
272 (guard (c ((nix-connection-error? c)
273 (write `(connection-error ,(nix-connection-error-file c)
274 ,(nix-connection-error-code c))))
275 ((nix-protocol-error? c)
276 (write `(protocol-error ,(nix-protocol-error-status c)
277 ,(nix-protocol-error-message c))))
279 (write `(exception))))
281 (let* ((files ',files)
282 (invalid (remove (cut valid-path? store <>)
284 (unless (null? invalid)
285 (write `(invalid-items ,invalid))
288 ;; TODO: When RECURSIVE? is true, we could send the list of store
289 ;; items in the closure so that the other end can filter out
290 ;; those it already has.
292 (write '(exporting)) ;we're ready
295 (setvbuf (current-output-port) 'none)
296 (export-paths store files (current-output-port)
297 #:recursive? ,recursive?))))))
299 (open-remote-input-pipe session
303 (object->string export))))))
305 (define (remote-system session)
306 "Return the system type as expected by Nix, usually ARCHITECTURE-KERNEL, of
307 the machine on the other end of SESSION."
308 (inferior-remote-eval '(begin (use-modules (guix utils)) (%current-system))
311 (define* (remote-authorize-signing-key key session #:optional become-command)
312 "Send KEY, a canonical sexp containing a public key, over SESSION and add it
313 to the system ACL file if it has not yet been authorized."
314 (inferior-remote-eval
316 (use-modules (guix build utils)
322 (define acl (current-acl))
323 (define key (string->canonical-sexp ,(canonical-sexp->string key)))
325 (unless (authorized-key? key)
326 (let ((acl (public-keys->acl (cons key (acl->public-keys acl)))))
327 (mkdir-p (dirname %acl-file))
328 (with-atomic-file-output %acl-file
329 (cut write-acl acl <>)))))
333 (define* (send-files local files remote
336 (log-port (current-error-port)))
337 "Send the subset of FILES from LOCAL (a local store) that's missing to
338 REMOTE, a remote store. When RECURSIVE? is true, send the closure of FILES.
339 Return the list of store items actually sent."
340 ;; Compute the subset of FILES missing on SESSION and send them.
341 (let* ((files (if recursive? (requisites local files) files))
342 (session (channel-get-session (store-connection-socket remote)))
343 (missing (inferior-remote-eval
346 (srfi srfi-1) (srfi srfi-26))
349 (remove (cut valid-path? store <>)
352 (count (length missing))
353 (sizes (map (lambda (item)
354 (path-info-nar-size (query-path-info local item)))
356 (port (store-import-channel session)))
357 (format log-port (N_ "sending ~a store item (~h MiB) to '~a'...~%"
358 "sending ~a store items (~h MiB) to '~a'...~%" count)
360 (inexact->exact (round (/ (reduce + 0 sizes) (expt 2. 20))))
361 (session-get session 'host))
363 ;; Send MISSING in topological order.
364 (export-paths local missing port)
366 ;; Tell the remote process that we're done. (In theory the end-of-archive
367 ;; mark of 'export-paths' would be enough, but in practice it's not.)
368 (channel-send-eof port)
370 ;; Wait for completion of the remote process and read the status sexp from
371 ;; PORT. Wait for the exit status only when 'read' completed; otherwise,
372 ;; we might wait forever if the other end is stuck.
373 (let* ((result (false-if-exception (read port)))
375 (zero? (channel-get-exit-status port)))))
380 (('protocol-error message)
382 (&store-protocol-error (message message) (status 42)))))
383 (('error key args ...)
385 (&store-protocol-error
386 (message (call-with-output-string
388 (print-exception port #f key args))))
392 (&store-protocol-error
393 (message "unknown error while sending files over SSH")
396 (define (remote-store-session remote)
397 "Return the SSH channel beneath REMOTE, a remote store as returned by
398 'connect-to-remote-daemon', or #f."
399 (channel-get-session (store-connection-socket remote)))
401 (define (remote-store-host remote)
402 "Return the name of the host REMOTE is connected to, where REMOTE is a
403 remote store as returned by 'connect-to-remote-daemon'."
404 (match (remote-store-session remote)
406 ((? session? session)
407 (session-get session 'host))))
409 (define* (file-retrieval-port files remote
411 "Return an input port from which to retrieve FILES (a list of store items)
412 from REMOTE, along with the number of items to retrieve (lower than or equal
413 to the length of FILES.)"
414 (values (store-export-channel (remote-store-session remote) files
415 #:recursive? recursive?)
416 (length files))) ;XXX: inaccurate when RECURSIVE? is true
418 (define-syntax raise-error
420 ((_ fmt args ... (=> hint-fmt hint-args ...))
423 (message (format #f fmt args ...)))
425 (hint (format #f hint-fmt hint-args ...))))))
429 (message (format #f fmt args ...))))))))
431 (define* (retrieve-files* files remote
432 #:key recursive? (log-port (current-error-port))
434 "Pass IMPORT an input port from which to read the sequence of FILES coming
435 from REMOTE. When RECURSIVE? is true, retrieve the closure of FILES."
436 (let-values (((port count)
437 (file-retrieval-port files remote
438 #:recursive? recursive?)))
439 (match (read port) ;read the initial status
441 (format #t (N_ "retrieving ~a store item from '~a'...~%"
442 "retrieving ~a store items from '~a'...~%" count)
443 count (remote-store-host remote))
452 (report-guile-error (remote-store-host remote)))
454 (report-module-error (remote-store-host remote)))
455 (('connection-error file code . _)
456 (raise-error (G_ "failed to connect to '~A' on remote host '~A': ~a")
457 file (remote-store-host remote) (strerror code)))
458 (('invalid-items items . _)
459 (raise-error (N_ "no such item on remote host '~A':~{ ~a~}"
460 "no such items on remote host '~A':~{ ~a~}"
462 (remote-store-host remote) items))
463 (('protocol-error status message . _)
464 (raise-error (G_ "protocol error on remote host '~A': ~a")
465 (remote-store-host remote) message))
467 (raise-error (G_ "failed to retrieve store items from '~a'")
468 (remote-store-host remote))))))
470 (define* (retrieve-files local files remote
471 #:key recursive? (log-port (current-error-port)))
472 "Retrieve FILES from REMOTE and import them using the 'import-paths' RPC on
473 LOCAL. When RECURSIVE? is true, retrieve the closure of FILES."
474 (retrieve-files* (remove (cut valid-path? local <>) files)
476 #:recursive? recursive?
478 #:import (lambda (port)
479 (import-paths local port))))
486 (define (report-guile-error host)
487 (raise-error (G_ "failed to start Guile on remote host '~A'") host
488 (=> (G_ "Make sure @command{guile} can be found in
489 @code{$PATH} on the remote host. Run @command{ssh ~A guile --version} to
493 (define (report-module-error host)
494 "Report an error about missing Guix modules on HOST."
495 ;; TRANSLATORS: Leave "Guile" untranslated.
496 (raise-error (G_ "Guile modules not found on remote host '~A'") host
497 (=> (G_ "Make sure @code{GUILE_LOAD_PATH} includes Guix'
498 own module directory. Run @command{ssh ~A env | grep GUILE_LOAD_PATH} to
502 ;;; ssh.scm ends here