services: postgresql: Use Guile datatypes.

* gnu/services/databases.scm (postgresql-config-file-compiler): Support Guile
datatypes in the "extra-config" field.
* gnu/tests/databases.scm (%postgresql-os): Test it.
* doc/guix.texi (Database Services): Document it.

2 files changed, 31 insertions, 17 deletions

diff --git a/gnu/services/databases.scm b/gnu/services/databases.scm
index d2dc5f0da8..bb0e40632e 100644
--- a/gnu/services/databases.scm
+++ b/gnu/services/databases.scm
@@ -115,22 +115,28 @@ host	all	all	::1/128 	md5"))
   (match file
     (($ <postgresql-config-file> log-destination hba-file
                                  ident-file extra-config)
-     (define (single-quote string)
-       (if string
-           (list "'" string "'")
-           '()))
-
-     (define contents
-       (append-map
-        (match-lambda
-          ((key) '())
-          ((key . #f) '())
-          ((key values ...) `(,key " = " ,@values "\n")))
-
-        `(("log_destination" ,@(single-quote log-destination))
-          ("hba_file" ,@(single-quote hba-file))
-          ("ident_file" ,@(single-quote ident-file))
-          ,@extra-config)))
+     ;; See: https://www.postgresql.org/docs/current/config-setting.html.
+    (define (format-value value)
+      (cond
+       ((boolean? value)
+        (list (if value "on" "off")))
+       ((number? value)
+        (list (number->string value)))
+       (else
+        (list "'" value "'"))))
+
+    (define contents
+      (append-map
+       (match-lambda
+         ((key) '())
+         ((key . #f) '())
+         ((key values ...)
+          `(,key " = " ,@(append-map format-value values) "\n")))
+
+       `(("log_destination" ,log-destination)
+         ("hba_file" ,hba-file)
+         ("ident_file" ,ident-file)
+         ,@extra-config)))
 
      (gexp->derivation
       "postgresql.conf"
diff --git a/gnu/tests/databases.scm b/gnu/tests/databases.scm
index 31d5ae4c6a..7338007919 100644
--- a/gnu/tests/databases.scm
+++ b/gnu/tests/databases.scm
@@ -218,7 +218,15 @@
   (simple-operating-system
    (service postgresql-service-type
             (postgresql-configuration
-             (postgresql postgresql-10)))))
+             (postgresql postgresql-10)
+             (config-file
+              (postgresql-config-file
+               (extra-config
+                '(("session_preload_libraries" "auto_explain")
+                  ("random_page_cost" 2)
+                  ("auto_explain.log_min_duration" "100 ms")
+                  ("work_mem" "500 MB")
+                  ("debug_print_plan" #t)))))))))
 
 (define (run-postgresql-test)
   "Run tests in %POSTGRESQL-OS."