Add GitLab Pages administration guide

doc/README.md

@@ -71,6 +71,7 @@
 - [Migrate GitLab CI to CE/EE](migrate_ci_to_ce/README.md) Follow this guide to migrate your existing GitLab CI data to GitLab CE/EE.
 - [Downgrade back to CE](downgrade_ee_to_ce/README.md) Follow this guide if you need to downgrade from EE to CE.
 - [Git LFS configuration](workflow/lfs/lfs_administration.md)
+- [GitLab Pages configuration](pages/administration.md)
 
 ## Contributor documentation
 

doc/pages/administration.md

+# GitLab Pages Administration
+
+_**Note:** This feature was [introduced][ee-80] in GitLab EE 8.3_
+
+If you are looking for ways to upload your static content in GitLab Pages, you
+probably want to read the [user documentation](README.md).
+
+## Configuration
+
+There are a couple of things to consider before enabling GitLab pages in your
+GitLab EE instance.
+
+1. You need to properly configure your DNS to point to the domain that pages
+   will be served
+1. Pages use a separate nginx configuration file which needs to be explicitly
+   added in the server under which GitLab EE runs
+
+Both of these settings are described in detail in the sections below.
+
+### DNS configuration
+
+GitLab Pages expect to run on their own virtual host. In your DNS you need to
+add a [wildcard DNS A record][wiki-wildcard-dns] pointing to the host that
+GitLab runs. For example, an entry would look like this:
+
+```
+*.gitlabpages.com. 60 IN A 1.2.3.4
+```
+
+where `gitlabpages.com` is the domain under which GitLab Pages will be served
+and `1.2.3.4` is the IP address of your GitLab instance.
+
+It is strongly advised to **not** use the GitLab domain to serve user pages.
+See [security](#security).
+
+### Omnibus package installations
+
+See the relevant documentation at <http://doc.gitlab.com/omnibus/settings/pages.html>.
+
+### Installations from source
+
+1. Go to the GitLab installation directory:
+
+   ```bash
+   cd /home/git/gitlab
+   ```
+
+1. Edit `gitlab.yml` and under the `pages` setting, set `enabled` to `true` in
+   order to enable the pages feature:
+
+   ```bash
+   ## GitLab Pages
+   pages:
+     enabled: true
+     # The location where pages are stored (default: shared/pages).
+     # path: shared/pages
+
+     # The domain under which the pages are served:
+     # http://group.example.com/project
+     # or project path can be a group page: group.example.com
+     host: example.com
+     port: 80 # Set to 443 if you serve the pages with HTTPS
+     https: false # Set to true if you serve the pages with HTTPS
+     ```
+
+1. Make sure you have copied the new `gitlab-pages` Nginx configuration file:
+
+  ```bash
+  sudo cp lib/support/nginx/gitlab-pages /etc/nginx/sites-available/gitlab-pages.conf
+  sudo ln -sf /etc/nginx/sites-{available,enabled}/gitlab-pages.conf
+  ```
+
+  Don't forget to add your domain name in the Nginx config. For example if your
+  GitLab pages domain is `gitlabpages.com`, replace
+
+  ```bash
+  server_name ~^(?<group>.*)\.YOUR_GITLAB_PAGES\.DOMAIN$;
+  ```
+
+  with
+
+  ```
+  server_name ~^(?<group>.*)\.gitlabpages\.com$;
+  ```
+
+  You must be extra careful to not remove the backslashes.
+
+1. Restart Nginx and GitLab:
+
+  ```bash
+  sudo service nginx restart
+  sudo service gitlab restart
+  ```
+
+### Running GitLab pages with HTTPS
+
+If you want the pages to be served under HTTPS, a wildcard SSL certificate is
+required.
+
+1. In `gitlab.yml`, set the port to `443` and https to `true`:
+
+   ```bash
+   ## GitLab Pages
+   pages:
+     enabled: true
+     # The location where pages are stored (default: shared/pages).
+     # path: shared/pages
+
+     # The domain under which the pages are served:
+     # http://group.example.com/project
+     # or project path can be a group page: group.example.com
+     host: gitlabpages.com
+     port: 443 # Set to 443 if you serve the pages with HTTPS
+     https: true # Set to true if you serve the pages with HTTPS
+     ```
+1. Use the `gitlab-pages-ssl` Nginx configuration file
+
+  ```bash
+  sudo cp lib/support/nginx/gitlab-pages-ssl /etc/nginx/sites-available/gitlab-pages-ssl.conf
+  sudo ln -sf /etc/nginx/sites-{available,enabled}/gitlab-pages.conf
+  ```
+
+  Make sure to edit the config and add your domain as well as correctly point
+  to the right location where the SSL certificates reside.
+
+## Set maximum pages size
+
+The maximum size of the unpacked archive can be configured in the Admin area
+under the Application settings in the **Maximum size of pages (MB)**.
+The default is 100MB.
+
+## Security
+
+You should strongly consider running GitLab pages under a different hostname
+than GitLab to prevent XSS.
+
+## How it works
+
+- The public/ is extracted from artifacts and content is served as static pages
+- Pages asynchronous worker use `dd` to limit the unpacked tar size
+- Pages are part of backups
+- Pages notify the deployment status using Commit Status API
+- Pages use a new sidekiq queue: pages
+
+[ee-80]: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/80
+[wiki-wildcard-dns]: https://en.wikipedia.org/wiki/Wildcard_DNS_record