summaryrefslogtreecommitdiff
path: root/gnu/services/configuration.scm
blob: dacfc52ba9eed7b1adbd5776e9da359525bb718f (about) (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 Andy Wingo <wingo@igalia.com>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2017, 2018 Clément Lassieur <clement@lassieur.org>
;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
;;; Copyright © 2021, 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2021 Andrew Tropin <andrew@trop.in>
;;; Copyright © 2022 Maxime Devos <maximedevos@telenet.be>
;;;
;;; 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 (gnu services configuration)
  #:use-module (guix packages)
  #:use-module (guix records)
  #:use-module (guix gexp)
  #:use-module ((guix utils) #:select (source-properties->location))
  #:use-module ((guix diagnostics)
                #:select (formatted-message location-file &error-location))
  #:use-module ((guix modules) #:select (file-name->module-name))
  #:use-module (guix i18n)
  #:autoload   (texinfo) (texi-fragment->stexi)
  #:autoload   (texinfo serialize) (stexi->texi)
  #:use-module (ice-9 curried-definitions)
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:export (configuration-field
            configuration-field-name
            configuration-field-type
            configuration-missing-field
            configuration-field-error
            configuration-field-serializer
            configuration-field-getter
            configuration-field-default-value-thunk
            configuration-field-documentation

            configuration-error?

            define-configuration
            define-configuration/no-serialization
            no-serialization

            serialize-configuration
            define-maybe
            define-maybe/no-serialization
            %unset-value
            maybe-value
            maybe-value-set?
            generate-documentation
            configuration->documentation
            empty-serializer
            serialize-package

            filter-configuration-fields

            interpose
            list-of

            list-of-strings?
            alist?
            serialize-file-like
            text-config?
            serialize-text-config
            generic-serialize-alist-entry
            generic-serialize-alist))

;;; Commentary:
;;;
;;; Syntax for creating Scheme bindings to complex configuration files.
;;;
;;; Code:

(define-condition-type &configuration-error &error
  configuration-error?)

(define (configuration-error message)
  (raise (condition (&message (message message))
                    (&configuration-error))))
(define (configuration-field-error loc field value)
  (raise (apply
          make-compound-condition
          (formatted-message (G_ "invalid value ~s for field '~a'")
                             value field)
          (condition (&configuration-error))
          (if loc
              (list (condition
                     (&error-location (location loc))))
              '()))))

(define (configuration-missing-field kind field)
  (configuration-error
   (format #f "~a configuration missing required field ~a" kind field)))
(define (configuration-missing-default-value kind field)
  (configuration-error
   (format #f "The field `~a' of the `~a' configuration record \
does not have a default value" field kind)))

(define-record-type* <configuration-field>
  configuration-field make-configuration-field configuration-field?
  (name configuration-field-name)
  (type configuration-field-type)
  (getter configuration-field-getter)
  (predicate configuration-field-predicate)
  (serializer configuration-field-serializer)
  (default-value-thunk configuration-field-default-value-thunk)
  (documentation configuration-field-documentation))

(define (serialize-configuration config fields)
  #~(string-append
     #$@(map (lambda (field)
               ((configuration-field-serializer field)
                (configuration-field-name field)
                ((configuration-field-getter field) config)))
             fields)))

(define-syntax-rule (id ctx parts ...)
  "Assemble PARTS into a raw (unhygienic) identifier."
  (datum->syntax ctx (symbol-append (syntax->datum parts) ...)))

(define (define-maybe-helper serialize? prefix syn)
  (syntax-case syn ()
    ((_ stem)
     (with-syntax
         ((stem?            (id #'stem #'stem #'?))
          (maybe-stem?      (id #'stem #'maybe- #'stem #'?))
          (serialize-stem   (if prefix
                                (id #'stem prefix #'serialize- #'stem)
                                (id #'stem #'serialize- #'stem)))
          (serialize-maybe-stem (if prefix
                                    (id #'stem prefix #'serialize-maybe- #'stem)
                                    (id #'stem #'serialize-maybe- #'stem))))
       #`(begin
           (define (maybe-stem? val)
             (or (not (maybe-value-set? val))
                 (stem? val)))
           #,@(if serialize?
                  (list #'(define (serialize-maybe-stem field-name val)
                            (if (stem? val)
                                (serialize-stem field-name val)
                                "")))
                  '()))))))

(define-syntax define-maybe
  (lambda (x)
    (syntax-case x (no-serialization prefix)
      ((_ stem (no-serialization))
       (define-maybe-helper #f #f #'(_ stem)))
      ((_ stem (prefix serializer-prefix))
       (define-maybe-helper #t #'serializer-prefix #'(_ stem)))
      ((_ stem)
       (define-maybe-helper #t #f #'(_ stem))))))

(define-syntax-rule (define-maybe/no-serialization stem)
  (define-maybe stem (no-serialization)))

(define (normalize-field-type+def s)
  (syntax-case s ()
    ((field-type def)
     (identifier? #'field-type)
     (values #'(field-type def)))
    ((field-type)
     (identifier? #'field-type)
     (values #'(field-type %unset-value)))
    (field-type
     (identifier? #'field-type)
     (values #'(field-type %unset-value)))))

(define (define-configuration-helper serialize? serializer-prefix syn)
  (syntax-case syn ()
    ((_ stem (field field-type+def doc custom-serializer ...) ...)
     (with-syntax
         ((((field-type def) ...)
           (map normalize-field-type+def #'(field-type+def ...))))
       (with-syntax
           (((field-getter ...)
             (map (lambda (field)
                    (id #'stem #'stem #'- field))
                  #'(field ...)))
            ((field-predicate ...)
             (map (lambda (type)
                    (id #'stem type #'?))
                  #'(field-type ...)))
            ((field-default ...)
             (map (match-lambda
                    ((field-type default-value)
                     default-value))
                  #'((field-type def) ...)))
            ((field-serializer ...)
             (map (lambda (type custom-serializer)
                    (and serialize?
                         (match custom-serializer
                           ((serializer)
                            serializer)
                           (()
                            (if serializer-prefix
                                (id #'stem
                                    serializer-prefix
                                    #'serialize- type)
                                (id #'stem #'serialize- type))))))
                  #'(field-type ...)
                  #'((custom-serializer ...) ...))))
         (define (field-sanitizer name pred)
           ;; Define a macro for use as a record field sanitizer, where NAME
           ;; is the name of the field and PRED is the predicate that tells
           ;; whether a value is valid for this field.
           #`(define-syntax #,(id #'stem #'validate- #'stem #'- name)
               (lambda (s)
                 ;; Make sure the given VALUE, for field NAME, passes PRED.
                 (syntax-case s ()
                   ((_ value)
                    (with-syntax ((name #'#,name)
                                  (pred #'#,pred)
                                  (loc (datum->syntax #'value
                                                      (syntax-source #'value))))
                      #'(if (pred value)
                            value
                            (configuration-field-error
                             (and=> 'loc source-properties->location)
                             'name value))))))))

         #`(begin
             ;; Define field validation macros.
             #,@(map field-sanitizer
                     #'(field ...)
                     #'(field-predicate ...))

             (define-record-type* #,(id #'stem #'< #'stem #'>)
               stem
               #,(id #'stem #'make- #'stem)
               #,(id #'stem #'stem #'?)
               #,@(map (lambda (name getter def)
                         #`(#,name #,getter (default #,def)
                                   (sanitize
                                    #,(id #'stem #'validate- #'stem #'- name))))
                       #'(field ...)
                       #'(field-getter ...)
                       #'(field-default ...))
               (%location #,(id #'stem #'stem #'-location)
                          (default (and=> (current-source-location)
                                          source-properties->location))
                          (innate)))

             (define #,(id #'stem #'stem #'-fields)
               (list (configuration-field
                      (name 'field)
                      (type 'field-type)
                      (getter field-getter)
                      (predicate field-predicate)
                      (serializer field-serializer)
                      (default-value-thunk
                        (lambda ()
                          (display '#,(id #'stem #'% #'stem))
                          (if (maybe-value-set? (syntax->datum field-default))
                              field-default
                              (configuration-missing-default-value
                               '#,(id #'stem #'% #'stem) 'field))))
                      (documentation doc))
                     ...))))))))

(define no-serialization         ;syntactic keyword for 'define-configuration'
  '(no serialization))

(define-syntax define-configuration
  (lambda (s)
    (syntax-case s (no-serialization prefix)
      ((_ stem (field field-type+def doc custom-serializer ...) ...
          (no-serialization))
       (define-configuration-helper
         #f #f #'(_ stem (field field-type+def doc custom-serializer ...)
                 ...)))
      ((_ stem  (field field-type+def doc custom-serializer ...) ...
          (prefix serializer-prefix))
       (define-configuration-helper
         #t #'serializer-prefix #'(_ stem (field field-type+def
                                                 doc custom-serializer ...)
                 ...)))
      ((_ stem (field field-type+def doc custom-serializer ...) ...)
       (define-configuration-helper
         #t #f #'(_ stem (field field-type+def doc custom-serializer ...)
                 ...))))))

(define-syntax-rule (define-configuration/no-serialization
                      stem (field field-type+def
                                  doc custom-serializer ...) ...)
  (define-configuration stem (field field-type+def
                                    doc custom-serializer ...) ...
    (no-serialization)))

(define (empty-serializer field-name val) "")
(define serialize-package empty-serializer)

;; Ideally this should be an implementation detail, but we export it
;; to provide a simpler API that enables unsetting a configuration
;; field that has a maybe type, but also a default value.  We give it
;; a value that sticks out to the reader when something goes wrong.
;;
;; An example use-case would be something like a network application
;; that uses a default port, but the field can explicitly be unset to
;; request a random port at startup.
(define %unset-value '%unset-marker%)

(define (maybe-value-set? value)
  "Predicate to check whether a 'maybe' value was explicitly provided."
  (not (eq? %unset-value value)))

;; Ideally there should be a compiler macro for this predicate, that expands
;; to a conditional that only instantiates the default value when needed.
(define* (maybe-value value #:optional (default #f))
  "Returns VALUE, unless it is the unset value, in which case it returns
DEFAULT."
  (if (maybe-value-set? value)
      value
      default))

;; A little helper to make it easier to document all those fields.
(define (generate-documentation documentation documentation-name)
  (define (str x) (object->string x))

  (define (package->symbol package)
    "Return the first symbol name of a package that matches PACKAGE, else #f."
    (let* ((module (file-name->module-name
                    (location-file (package-location package))))
           (symbols (filter-map
                     identity
                     (module-map (lambda (symbol var)
                                   (and (equal? package (variable-ref var))
                                        symbol))
                                 (resolve-module module)))))
      (if (null? symbols)
          #f
          (first symbols))))

  (define (generate configuration-name)
    (match (assq-ref documentation configuration-name)
      ((fields . sub-documentation)
       `((deftp (% (category "Data Type") (name ,(str configuration-name)))
           (para "Available " (code ,(str configuration-name)) " fields are:")
           (table
            (% (formatter (asis)))
            ,@(map
               (lambda (f)
                 (let ((field-name (configuration-field-name f))
                       (field-type (configuration-field-type f))
                       (field-docs (cdr (texi-fragment->stexi
                                         (configuration-field-documentation f))))
                       (default (catch #t
                                  (configuration-field-default-value-thunk f)
                                  (lambda _ '%invalid))))
                   (define (show-default? val)
                     (or (string? val) (number? val) (boolean? val)
                         (package? val)
                         (and (symbol? val) (not (eq? val '%invalid)))
                         (and (list? val) (and-map show-default? val))))

                   (define (show-default val)
                     (cond
                      ((package? val)
                       (symbol->string (package->symbol val)))
                      (else (str val))))

                   `(entry (% (heading
                               (code ,(str field-name))
                               ,@(if (show-default? default)
                                     `(" (default: "
                                       (code ,(show-default default)) ")")
                                     '())
                               " (type: " ,(str field-type) ")"))
                           (para ,@field-docs)
                           ,@(append-map
                              generate
                              (or (assq-ref sub-documentation field-name)
                                  '())))))
               fields)))))))
  (stexi->texi `(*fragment* . ,(generate documentation-name))))

(define (configuration->documentation configuration-symbol)
  "Take CONFIGURATION-SYMBOL, the symbol corresponding to the name used when
defining a configuration record with DEFINE-CONFIGURATION, and output the
Texinfo documentation of its fields."
  ;; This is helper for a simple, straight-forward application of
  ;; GENERATE-DOCUMENTATION.
  (let ((fields-getter (module-ref (current-module)
                                   (symbol-append configuration-symbol
                                                  '-fields))))
    (display (generate-documentation `((,configuration-symbol ,fields-getter))
                                     configuration-symbol))))

(define* (filter-configuration-fields configuration-fields fields
                                      #:optional negate?)
  "Retrieve the fields listed in FIELDS from CONFIGURATION-FIELDS.
If NEGATE? is @code{#t}, retrieve all fields except FIELDS."
  (filter (lambda (field)
            (let ((member? (member (configuration-field-name field) fields)))
              (if (not negate?) member? (not member?))))
          configuration-fields))


(define* (interpose ls  #:optional (delimiter "\n") (grammar 'infix))
  "Same as @code{string-join}, but without join and string, returns a
DELIMITER interposed LS.  Support 'infix and 'suffix GRAMMAR values."
  (when (not (member grammar '(infix suffix)))
    (raise
     (formatted-message
      (G_ "The GRAMMAR value must be 'infix or 'suffix, but ~a provided.")
      grammar)))
  (fold-right (lambda (e acc)
                (cons e
                      (if (and (null? acc) (eq? grammar 'infix))
                          acc
                          (cons delimiter acc))))
              '() ls))

(define (list-of pred?)
  "Return a procedure that takes a list and check if all the elements of
the list result in @code{#t} when applying PRED? on them."
    (lambda (x)
      (if (list? x)
          (every pred? x)
          #f)))


(define list-of-strings?
  (list-of string?))

(define alist? list?)

(define serialize-file-like empty-serializer)

(define (text-config? config)
  (list-of file-like?))

(define (serialize-text-config field-name val)
  #~(string-append
     #$@(interpose
         (map
          (lambda (e)
            #~(begin
                (use-modules (ice-9 rdelim))
                (with-fluids ((%default-port-encoding "UTF-8"))
                  (with-input-from-file #$e read-string))))
          val)
         "\n" 'suffix)))

(define ((generic-serialize-alist-entry serialize-field) entry)
  "Apply the SERIALIZE-FIELD procedure on the field and value of ENTRY."
  (match entry
    ((field . val) (serialize-field field val))))

(define (generic-serialize-alist combine serialize-field fields)
  "Generate a configuration from an association list FIELDS.

SERIALIZE-FIELD is a procedure that takes two arguments, it will be
applied on the fields and values of FIELDS using the
@code{generic-serialize-alist-entry} procedure.

COMBINE is a procedure that takes one or more arguments and combines
all the alist entries into one value, @code{string-append} or
@code{append} are usually good candidates for this.

See the @code{serialize-alist} procedure in `@code{(gnu home services
version-control}' for an example usage.)}"
  (apply combine
         (map (generic-serialize-alist-entry serialize-field) fields)))