Enable Gitlab-Pages for subgroups

GitLab Pages supports projects hosted under a subgroup, but not subgroup
websites. That means that only the highest-level group supports

i.e.:
You created a group for your engineering department called
`engineering`, a subgroup for all your documentation websites called
`docs`,and a project within this subgroup is called `workflows`.
Your project URL is `https://gitlab.com/engineering/docs/workflows/`.
Once you enable GitLab Pages for this project, the site will live under
`https://engineering.gitlab.io/docs/workflows`.

GITLAB_PAGES_VERSION

-1.3.1
+1.4.0

app/models/project.rb

@@ -1531,7 +1531,7 @@ class Project < ActiveRecord::Base
   end
 
   def pages_available?
-    Gitlab.config.pages.enabled && !namespace.subgroup?
+    Gitlab.config.pages.enabled
   end
 
   def remove_private_deploy_keys

changelogs/unreleased/ac-pages-subgroups.yml

+---
+title: Pages for subgroups
+merge_request: 23505
+author:
+type: added

doc/user/group/subgroups/index.md

@@ -164,9 +164,11 @@ and you can choose the group of people to be notified.
 
 Here's a list of what you can't do with subgroups:
 
-- [GitLab Pages](../../project/pages/index.md) are not currently working for
-  projects hosted under a subgroup. That means that only projects hosted under
-  the first parent group will work.
+- [GitLab Pages](../../project/pages/index.md) supports projects hosted under
+  a subgroup, but not subgroup websites.
+  That means that only the highest-level group supports
+  [group websites](../../project/pages/introduction.html#user-or-group-pages),
+  although you can have project websites under a subgroup.
 - It is not possible to share a project with a group that's an ancestor of
   the group the project is in. That means you can only share as you walk down
   the hierarchy. For example, `group/subgroup01/project` **cannot** be shared

doc/user/project/pages/getting_started_part_one.md

@@ -85,6 +85,12 @@ and a project within this group is called `blog`. Your project
 URL is `https://gitlab.com/websites/blog/`. Once you enable
 GitLab Pages for this project, the site will live under
 `https://websites.gitlab.io/blog/`.
+- You created a group for your engineering department called `engineering`,
+a subgroup for all your documentation websites called `docs`,
+and a project within this subgroup is called `workflows`. Your project
+URL is `https://gitlab.com/engineering/docs/workflows/`. Once you enable
+GitLab Pages for this project, the site will live under
+`https://engineering.gitlab.io/docs/workflows`.
 
 #### User and Group Websites
 
@@ -98,8 +104,7 @@ Once you enable GitLab Pages for your project,
 your website will be published under `https://websites.gitlab.io`.
 
 >**Note:**
-GitLab Pages [does **not** support subgroups](../../group/subgroups/index.md#limitations).
-You can only create the highest level group website.
+Support for subgroup project's websites was introduced in GitLab 11.8.
 
 **General example:**
 

doc/user/project/pages/introduction.md

@@ -38,6 +38,7 @@ be served on.
 | Group pages | `groupname.example.io` | `http(s)://groupname.example.io` |
 | Project pages owned by a user  | `projectname` | `http(s)://username.example.io/projectname` |
 | Project pages owned by a group | `projectname` | `http(s)://groupname.example.io/projectname`|
+| Project pages owned by a subgroup | `subgroup/projectname` | `http(s)://groupname.example.io/subgroup/projectname`|
 
 > **Warning:**
 > There are some known [limitations](#limitations) regarding namespaces served
@@ -494,8 +495,8 @@ don't redirect HTTP to HTTPS.
 
 [rfc]: https://tools.ietf.org/html/rfc2818#section-3.1 "HTTP Over TLS RFC"
 
-GitLab Pages [does **not** support subgroups](../../group/subgroups/index.md#limitations).
-You can only create the highest level group website.
+GitLab Pages [does **not** support group websites for subgroups](../../group/subgroups/index.md#limitations).
+You can only create the highest-level group website.
 
 ## Redirects in GitLab Pages
 

spec/controllers/projects/pages_controller_spec.rb

@@ -28,10 +28,10 @@ describe Projects::PagesController do
       let(:group) { create(:group, :nested) }
       let(:project) { create(:project, namespace: group) }
 
-      it 'returns a 404 status code' do
+      it 'returns a 200 status code' do
         get :show, params: request_params
 
-        expect(response).to have_gitlab_http_status(404)
+        expect(response).to have_gitlab_http_status(200)
       end
     end
   end

spec/models/project_spec.rb

@@ -3087,7 +3087,7 @@ describe Project do
     context 'when the project is in a subgroup' do
       let(:group) { create(:group, :nested) }
 
-      it { is_expected.to be(false) }
+      it { is_expected.to be(true) }
     end
   end