services: Modernize redis service.

* gnu/services/databases.scm
(redis-configuration): Rewrite using `define-configuration'.
(redis-shepherd-service): Honor it.
* doc/guix.texi (Database Services) <redis>: Regenerate
documentation.

Change-Id: I5b99822ca3d8d23fb5133497d00eada0336d0c65
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
Merges: #2158

doc/guix.texi

@@ -28343,30 +28343,47 @@ Additional command line options to pass to @code{memcached}.
 
 @subsubheading Redis
 
+@uref{https://redis.io/, Redis} is an in-memory data store used
+by millions of developers as a cache, vector database, document
+database, streaming engine, and message broker. Redis has built-in
+replication and different levels of on-disk persistence. It supports
+complex data types (for example, strings, hashes, lists, sets, sorted
+sets, and JSON), with atomic operations defined on those data types.
+
 @defvar redis-service-type
-This is the service type for the @uref{https://redis.io/, Redis}
+Type of the service that runs @command{redis}, an in-memory data store.
-key/value store, whose value is a @code{redis-configuration} object.
+The value for this service is a @code{<redis-configuration>} object.
 @end defvar
 
+@c %start of fragment
+
 @deftp {Data Type} redis-configuration
-Data type representing the configuration of redis.
+Available @code{redis-configuration} fields are:
 
 @table @asis
-@item @code{redis} (default: @code{redis})
+@item @code{redis} (default: @code{redis}) (type: package)
 The Redis package to use.
 
-@item @code{bind} (default: @code{"127.0.0.1"})
+@item @code{bind} (default: @code{"127.0.0.1"}) (type: string)
 Network interface on which to listen.
 
-@item @code{port} (default: @code{6379})
+@item @code{port} (default: @code{6379}) (type: number)
 Port on which to accept connections on, a value of 0 will disable
 listening on a TCP socket.
 
-@item @code{working-directory} (default: @code{"/var/lib/redis"})
+@item @code{working-directory} (default: @code{"/var/lib/redis"}) (type: string)
 Directory in which to store the database and related files.
+
+@item @code{config-file} (type: maybe-string)
+Default location for config file.
+
 @end table
+
 @end deftp
 
+
+@c %end of fragment
+
 @node Mail Services
 @subsection Mail Services
 

gnu/services/databases.scm

@@ -28,6 +28,7 @@
 
 (define-module (gnu services databases)
   #:use-module (gnu services)
+  #:use-module (gnu services configuration)
   #:use-module (gnu services shepherd)
   #:use-module (gnu system shadow)
   #:autoload   (gnu system accounts) (default-shell)
@@ -786,19 +787,29 @@ port=" (number->string port) "
 ;;; Redis
 ;;;
 
-(define-record-type* <redis-configuration>
+(define-maybe string)
-  redis-configuration make-redis-configuration
+
-  redis-configuration?
+(define (uglify-field-name field-name)
-  (redis             redis-configuration-redis ;file-like
+  (string-delete #\? (symbol->string field-name)))
-                     (default redis))
+
-  (bind              redis-configuration-bind
+(define (serialize-field field-name val)
-                     (default "127.0.0.1"))
+  #~(format #f "~a=~a\n" #$(uglify-field-name field-name) #$val))
-  (port              redis-configuration-port
+
-                     (default 6379))
+(define serialize-string serialize-field)
-  (working-directory redis-configuration-working-directory
+(define serialize-number serialize-field)
-                     (default "/var/lib/redis"))
+
-  (config-file       redis-configuration-config-file
+(define-configuration redis-configuration
-                     (default #f)))
+  (redis (package redis)
+         "The Redis package to use.")
+  (bind (string "127.0.0.1")
+        "Network interface on which to listen.")
+  (port (number 6379)
+        "Port on which to accept connections on,
+a value of 0 will disable listening on a TCP socket.")
+  (working-directory (string "/var/lib/redis")
+                     "Directory in which to store the
+database and related files.")
+  (config-file maybe-string "Default location for config file."))
 
 (define (default-redis.conf bind port working-directory)
   (mixed-text-file "redis.conf"
@@ -832,7 +843,8 @@ port=" (number->string port) "
   (match-lambda
     (($ <redis-configuration> redis bind port working-directory config-file)
      (let ((config-file
-            (or config-file
+            (if (maybe-value-set? config-file)
+                config-file
                 (default-redis.conf bind port working-directory))))
        (list (shepherd-service
               (provision '(redis))
@@ -857,3 +869,9 @@ port=" (number->string port) "
                                           (const %redis-accounts))))
                 (default-value (redis-configuration))
                 (description "Run Redis, a caching key/value store.")))
+
+;;;
+;;; Generate documentation.
+;;;
+(define (redis-generate-doc)
+  (configuration->documentation 'redis-configuration))