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