doc: ci/yaml expire_in: the value is in seconds

app/views/admin/application_settings/_ci_cd.html.haml

@@ -38,6 +38,8 @@
       .form-text.text-muted
         Set the default expiration time for each job's artifacts.
         0 for unlimited.
+        The default unit is in seconds, but you can define an alternative. For example:
+        <code>4 mins 2 sec</code>, <code>2h42min</code>.
         = link_to icon('question-circle'), help_page_path('user/admin_area/settings/continuous_integration', anchor: 'default-artifacts-expiration')
 
   = f.submit 'Save changes', class: "btn btn-success"

doc/ci/yaml/README.md

@@ -1075,8 +1075,10 @@ keep artifacts forever.
 After their expiry, artifacts are deleted hourly by default (via a cron job),
 and are not accessible anymore.
 
-The value of `expire_in` is an elapsed time. Examples of parsable values:
+The value of `expire_in` is an elapsed time in seconds, unless a unit is
+provided. Examples of parsable values:
 
+- '42'
 - '3 mins 4 sec'
 - '2 hrs 20 min'
 - '2h20min'

doc/user/admin_area/settings/continuous_integration.md

@@ -21,8 +21,9 @@ that this setting is set for each job.
 The default expiration time of the [job artifacts][art-yml] can be set in
 the Admin area of your GitLab instance. The syntax of duration is described
 in [artifacts:expire_in][duration-syntax]. The default is `30 days`. Note that
-this setting is set for each job. Set it to 0 if you don't want default
-expiration.
+this setting is set for each job. Set it to `0` if you don't want default
+expiration. The default unit is in seconds.
+
 
 1. Go to **Admin area > Settings** (`/admin/application_settings`).