services: nginx: Make logging level configurable.

* gnu/services/web.scm (<nginx-configuration>)[log-level]: New field.
(assert-valid-log-level): New procedure.
(default-nginx-config): Make log-level configurable.
* doc/guix.texi (Web Services): Document it.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

doc/guix.texi

@@ -29889,6 +29889,11 @@ started.
 @item @code{log-directory} (default: @code{"/var/log/nginx"})
 The directory to which NGinx will write log files.
 
+@item @code{log-level} (default: @code{'error}) (type: symbol)
+Logging level, which can be any of the following values: @code{'debug},
+@code{'info}, @code{'notice}, @code{'warn}, @code{'error}, @code{'crit},
+@code{'alert}, or @code{'emerg}.
+
 @item @code{run-directory} (default: @code{"/var/run/nginx"})
 The directory in which NGinx will create a pid file, and write temporary
 files.

gnu/services/web.scm

@@ -15,6 +15,7 @@
 ;;; Copyright © 2020 Oleg Pykhalov <go.wigust@gmail.com>
 ;;; Copyright © 2020, 2021 Alexandru-Sergiu Marton <brown121407@posteo.ro>
 ;;; Copyright © 2022 Simen Endsjø <simendsjo@gmail.com>
+;;; Copyright © 2023 Bruno Victal <mirai@makinata.eu>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -51,6 +52,8 @@
   #:use-module (gnu packages logging)
   #:use-module (gnu packages mail)
   #:use-module (gnu packages rust-apps)
+  #:autoload   (guix i18n) (G_)
+  #:use-module (guix diagnostics)
   #:use-module (guix packages)
   #:use-module (guix records)
   #:use-module (guix modules)
@@ -61,6 +64,7 @@
   #:use-module ((guix packages) #:select (package-version))
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-34)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (httpd-configuration
@@ -96,6 +100,7 @@
             nginx-configuration-nginx
             nginx-configuration-shepherd-requirement
             nginx-configuration-log-directory
+            nginx-configuration-log-level
             nginx-configuration-run-directory
             nginx-configuration-server-blocks
             nginx-configuration-upstream-blocks
@@ -562,6 +567,9 @@
                         (default '()))              ;list of symbols
   (log-directory nginx-configuration-log-directory  ;string
                  (default "/var/log/nginx"))
+  (log-level     nginx-configuration-log-level
+                 (sanitize assert-valid-log-level)
+                 (default 'error))
   (run-directory nginx-configuration-run-directory  ;string
                  (default "/var/run/nginx"))
   (server-blocks nginx-configuration-server-blocks
@@ -584,6 +592,14 @@
   (file          nginx-configuration-file         ;#f | string | file-like
                  (default #f)))
 
+(define (assert-valid-log-level level)
+  "Ensure @var{level} is one of @code{'debug}, @code{'info}, @code{'notice},
+@code{'warn}, @code{'error}, @code{'crit}, @code{'alert}, or @code{'emerg}."
+  (unless (memq level '(debug info notice warn error crit alert emerg))
+    (raise
+     (formatted-message (G_ "unknown log level '~a'~%") level)))
+  level)
+
 (define (config-domain-strings names)
  "Return a string denoting the nginx config representation of NAMES, a list
 of domain names."
@@ -692,6 +708,7 @@ of index files."
   (match-record config
                 <nginx-configuration>
                 (nginx log-directory run-directory
+                 log-level
                  server-blocks upstream-blocks
                  server-names-hash-bucket-size
                  server-names-hash-bucket-max-size
@@ -704,7 +721,7 @@ of index files."
           (flatten
            "user nginx nginx;\n"
            "pid " run-directory "/pid;\n"
-           "error_log " log-directory "/error.log info;\n"
+           "error_log " log-directory "/error.log " (symbol->string log-level) ";\n"
            (map emit-load-module modules)
            (map emit-global-directive global-directives)
            "http {\n"