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240b57f0 | 1 | ;;; GNU Guix --- Functional package management for GNU |
bb64b2e7 | 2 | ;;; Copyright © 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org> |
5e03b122 | 3 | ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com> |
240b57f0 LC |
4 | ;;; |
5 | ;;; This file is part of GNU Guix. | |
6 | ;;; | |
7 | ;;; GNU Guix is free software; you can redistribute it and/or modify it | |
8 | ;;; under the terms of the GNU General Public License as published by | |
9 | ;;; the Free Software Foundation; either version 3 of the License, or (at | |
10 | ;;; your option) any later version. | |
11 | ;;; | |
12 | ;;; GNU Guix is distributed in the hope that it will be useful, but | |
13 | ;;; WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | ;;; GNU General Public License for more details. | |
16 | ;;; | |
17 | ;;; You should have received a copy of the GNU General Public License | |
18 | ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. | |
19 | ||
20 | (define-module (gnu services herd) | |
240b57f0 | 21 | #:use-module (srfi srfi-1) |
183605c8 | 22 | #:use-module (srfi srfi-9) |
240b57f0 | 23 | #:use-module (srfi srfi-11) |
8bf92e39 LC |
24 | #:use-module (srfi srfi-34) |
25 | #:use-module (srfi srfi-35) | |
240b57f0 | 26 | #:use-module (ice-9 match) |
5e03b122 | 27 | #:export (%shepherd-socket-file |
6aeae5b9 | 28 | shepherd-message-port |
5e03b122 MO |
29 | |
30 | shepherd-error? | |
8bf92e39 LC |
31 | service-not-found-error? |
32 | service-not-found-error-service | |
33 | action-not-found-error? | |
34 | action-not-found-error-service | |
35 | action-not-found-error-action | |
36 | action-exception-error? | |
37 | action-exception-error-service | |
38 | action-exception-error-action | |
39 | action-exception-error-key | |
40 | action-exception-error-arguments | |
41 | unknown-shepherd-error? | |
42 | unknown-shepherd-error-sexp | |
43 | ||
5c793753 | 44 | live-service |
183605c8 LC |
45 | live-service? |
46 | live-service-provision | |
47 | live-service-requirement | |
48 | live-service-running | |
5c793753 | 49 | live-service-canonical-name |
183605c8 | 50 | |
147c5aa5 | 51 | with-shepherd-action |
8bf92e39 | 52 | current-services |
240b57f0 LC |
53 | unload-services |
54 | unload-service | |
55 | load-services | |
4245ddcb | 56 | load-services/safe |
0642838b CB |
57 | start-service |
58 | stop-service)) | |
240b57f0 LC |
59 | |
60 | ;;; Commentary: | |
61 | ;;; | |
62 | ;;; This module provides an interface to the GNU Shepherd, similar to the | |
63 | ;;; 'herd' command. Essentially it implements a subset of the (shepherd comm) | |
64 | ;;; module, but focusing only on the parts relevant to 'guix system | |
65 | ;;; reconfigure'. | |
66 | ;;; | |
67 | ;;; Code: | |
68 | ||
69 | (define %shepherd-socket-file | |
5e03b122 | 70 | (make-parameter "/var/run/shepherd/socket")) |
240b57f0 | 71 | |
5e03b122 | 72 | (define* (open-connection #:optional (file (%shepherd-socket-file))) |
240b57f0 LC |
73 | "Open a connection to the daemon, using the Unix-domain socket at FILE, and |
74 | return the socket." | |
75 | ;; The protocol is sexp-based and UTF-8-encoded. | |
76 | (with-fluids ((%default-port-encoding "UTF-8")) | |
77 | (let ((sock (socket PF_UNIX SOCK_STREAM 0)) | |
78 | (address (make-socket-address PF_UNIX file))) | |
79 | (catch 'system-error | |
80 | (lambda () | |
81 | (connect sock address) | |
bb64b2e7 | 82 | (setvbuf sock 'block 1024) |
240b57f0 | 83 | sock) |
1d6b7d58 LC |
84 | (lambda args |
85 | (close-port sock) | |
86 | (apply throw args)))))) | |
240b57f0 LC |
87 | |
88 | (define-syntax-rule (with-shepherd connection body ...) | |
89 | "Evaluate BODY... with CONNECTION bound to an open socket to PID 1." | |
90 | (let ((connection (open-connection))) | |
89a26478 LC |
91 | (dynamic-wind |
92 | (const #t) | |
93 | (lambda () | |
94 | body ...) | |
95 | (lambda () | |
96 | (close-port connection))))) | |
240b57f0 | 97 | |
8bf92e39 LC |
98 | (define-condition-type &shepherd-error &error |
99 | shepherd-error?) | |
100 | ||
101 | (define-condition-type &service-not-found-error &shepherd-error | |
102 | service-not-found-error? | |
103 | (service service-not-found-error-service)) | |
104 | ||
105 | (define-condition-type &action-not-found-error &shepherd-error | |
106 | action-not-found-error? | |
107 | (service action-not-found-error-service) | |
108 | (action action-not-found-error-action)) | |
109 | ||
110 | (define-condition-type &action-exception-error &shepherd-error | |
111 | action-exception-error? | |
112 | (service action-exception-error-service) | |
113 | (action action-exception-error-action) | |
114 | (key action-exception-error-key) | |
115 | (args action-exception-error-arguments)) | |
116 | ||
117 | (define-condition-type &unknown-shepherd-error &shepherd-error | |
118 | unknown-shepherd-error? | |
119 | (sexp unknown-shepherd-error-sexp)) | |
120 | ||
121 | (define (raise-shepherd-error error) | |
122 | "Raise an error condition corresponding to ERROR, an sexp received by a | |
123 | shepherd client in reply to COMMAND, a command object. Return #t if ERROR | |
124 | does not denote an error." | |
240b57f0 LC |
125 | (match error |
126 | (('error ('version 0 x ...) 'service-not-found service) | |
8bf92e39 LC |
127 | (raise (condition (&service-not-found-error |
128 | (service service))))) | |
240b57f0 | 129 | (('error ('version 0 x ...) 'action-not-found action service) |
8bf92e39 LC |
130 | (raise (condition (&action-not-found-error |
131 | (service service) | |
132 | (action action))))) | |
240b57f0 LC |
133 | (('error ('version 0 x ...) 'action-exception action service |
134 | key (args ...)) | |
8bf92e39 LC |
135 | (raise (condition (&action-exception-error |
136 | (service service) | |
137 | (action action) | |
138 | (key key) (args args))))) | |
240b57f0 | 139 | (('error . _) |
8bf92e39 | 140 | (raise (condition (&unknown-shepherd-error (sexp error))))) |
240b57f0 LC |
141 | (#f ;not an error |
142 | #t))) | |
143 | ||
6aeae5b9 LC |
144 | (define shepherd-message-port |
145 | ;; Port where messages coming from shepherd are printed. | |
146 | (make-parameter (current-error-port))) | |
147 | ||
240b57f0 | 148 | (define (display-message message) |
6aeae5b9 | 149 | (format (shepherd-message-port) "shepherd: ~a~%" message)) |
240b57f0 LC |
150 | |
151 | (define* (invoke-action service action arguments cont) | |
152 | "Invoke ACTION on SERVICE with ARGUMENTS. On success, call CONT with the | |
7d14082d LC |
153 | list of results (one result per instance with the name SERVICE). Otherwise |
154 | return #f." | |
240b57f0 LC |
155 | (with-shepherd sock |
156 | (write `(shepherd-command (version 0) | |
157 | (action ,action) | |
158 | (service ,service) | |
159 | (arguments ,arguments) | |
160 | (directory ,(getcwd))) | |
161 | sock) | |
162 | (force-output sock) | |
163 | ||
164 | (match (read sock) | |
dc7b3e56 | 165 | (('reply ('version 0 _ ...) ('result result) ('error #f) |
240b57f0 LC |
166 | ('messages messages)) |
167 | (for-each display-message messages) | |
168 | (cont result)) | |
169 | (('reply ('version 0 x ...) ('result y) ('error error) | |
170 | ('messages messages)) | |
171 | (for-each display-message messages) | |
8bf92e39 | 172 | (raise-shepherd-error error) |
240b57f0 LC |
173 | #f) |
174 | (x | |
8bf92e39 | 175 | ;; invalid reply |
240b57f0 LC |
176 | #f)))) |
177 | ||
178 | (define-syntax-rule (with-shepherd-action service (action args ...) | |
179 | result body ...) | |
147c5aa5 LC |
180 | "Invoke ACTION on SERVICE with the given ARGS, and evaluate BODY with RESULT |
181 | bound to the action's result." | |
240b57f0 LC |
182 | (invoke-action service action (list args ...) |
183 | (lambda (result) body ...))) | |
184 | ||
185 | (define-syntax alist-let* | |
186 | (syntax-rules () | |
187 | "Bind the given KEYs in EXP to the corresponding items in ALIST. ALIST | |
188 | is assumed to be a list of two-element tuples rather than a traditional list | |
189 | of pairs." | |
190 | ((_ alist (key ...) exp ...) | |
191 | (let ((key (and=> (assoc-ref alist 'key) car)) ...) | |
192 | exp ...)))) | |
193 | ||
183605c8 LC |
194 | ;; Information about live Shepherd services. |
195 | (define-record-type <live-service> | |
196 | (live-service provision requirement running) | |
197 | live-service? | |
198 | (provision live-service-provision) ;list of symbols | |
199 | (requirement live-service-requirement) ;list of symbols | |
200 | (running live-service-running)) ;#f | object | |
201 | ||
5c793753 JK |
202 | (define (live-service-canonical-name service) |
203 | "Return the 'canonical name' of SERVICE." | |
204 | (first (live-service-provision service))) | |
205 | ||
240b57f0 | 206 | (define (current-services) |
183605c8 LC |
207 | "Return the list of currently defined Shepherd services, represented as |
208 | <live-service> objects. Return #f if the list of services could not be | |
209 | obtained." | |
7d14082d LC |
210 | (with-shepherd-action 'root ('status) results |
211 | ;; We get a list of results, one for each service with the name 'root'. | |
212 | ;; In practice there's only one such service though. | |
213 | (match results | |
214 | ((services _ ...) | |
215 | (match services | |
216 | ((('service ('version 0 _ ...) _ ...) ...) | |
217 | (map (lambda (service) | |
218 | (alist-let* service (provides requires running) | |
219 | (live-service provides requires running))) | |
220 | services)) | |
221 | (x | |
222 | #f)))))) | |
240b57f0 LC |
223 | |
224 | (define (unload-service service) | |
225 | "Unload SERVICE, a symbol name; return #t on success." | |
226 | (with-shepherd-action 'root ('unload (symbol->string service)) result | |
7d14082d | 227 | (first result))) |
240b57f0 LC |
228 | |
229 | (define (%load-file file) | |
230 | "Load FILE in the Shepherd." | |
231 | (with-shepherd-action 'root ('load file) result | |
7d14082d | 232 | (first result))) |
240b57f0 LC |
233 | |
234 | (define (eval-there exp) | |
235 | "Eval EXP in the Shepherd." | |
236 | (with-shepherd-action 'root ('eval (object->string exp)) result | |
7d14082d | 237 | (first result))) |
240b57f0 LC |
238 | |
239 | (define (load-services files) | |
240 | "Load and register the services from FILES, where FILES contain code that | |
241 | returns a shepherd <service> object." | |
242 | (eval-there `(register-services | |
243 | ,@(map (lambda (file) | |
244 | `(primitive-load ,file)) | |
245 | files)))) | |
246 | ||
4245ddcb CZ |
247 | (define (load-services/safe files) |
248 | "This is like 'load-services', but make sure only the subset of FILES that | |
249 | can be safely reloaded is actually reloaded. | |
250 | ||
251 | This is done to accommodate the Shepherd < 0.15.0 where services lacked the | |
252 | 'replacement' slot, and where 'register-services' would throw an exception | |
253 | when passed a service with an already-registered name." | |
254 | (eval-there `(let* ((services (map primitive-load ',files)) | |
255 | (slots (map slot-definition-name | |
256 | (class-slots <service>))) | |
257 | (can-replace? (memq 'replacement slots))) | |
258 | (define (registered? service) | |
259 | (not (null? (lookup-services (canonical-name service))))) | |
260 | ||
261 | (apply register-services | |
262 | (if can-replace? | |
263 | services | |
264 | (remove registered? services)))))) | |
265 | ||
ca0c43ec MO |
266 | (define* (start-service name #:optional (arguments '())) |
267 | (invoke-action name 'start arguments | |
268 | (lambda (result) | |
269 | result))) | |
240b57f0 | 270 | |
0642838b CB |
271 | (define (stop-service name) |
272 | (with-shepherd-action name ('stop) result | |
273 | result)) | |
274 | ||
240b57f0 LC |
275 | ;; Local Variables: |
276 | ;; eval: (put 'alist-let* 'scheme-indent-function 2) | |
277 | ;; eval: (put 'with-shepherd 'scheme-indent-function 1) | |
278 | ;; eval: (put 'with-shepherd-action 'scheme-indent-function 3) | |
279 | ;; End: | |
280 | ||
281 | ;;; herd.scm ends here |