Add docs for Let's Encrypt integration

* Add deprecation warning to old integration
* Add user docs
* Add admin docs

app/views/projects/pages_domains/_form.html.haml

@@ -33,7 +33,7 @@
             = sprite_icon("status_success_borderless", size: 16, css_class: "toggle-icon-svg toggle-status-checked")
             = sprite_icon("status_failed_borderless", size: 16, css_class: "toggle-icon-svg toggle-status-unchecked")
         %p.text-secondary.mt-3
-          - docs_link_url = help_page_path("user/project/pages/lets_encrypt_for_gitlab_pages.md", anchor: "lets-encrypt-for-gitlab-pages")
+          - docs_link_url = help_page_path("user/project/pages/custom_domains_ssl_tls_certification/lets_encrypt_integration.md")
           - docs_link_start = "<a href=\"%{docs_link_url}\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"text-nowrap\">".html_safe % { docs_link_url: docs_link_url }
           - docs_link_end = "</a>".html_safe
           = _("Let's Encrypt is a free, automated, and open certificate authority (CA) that gives digital certificates in order to enable HTTPS (SSL/TLS) for websites. Learn more about Let's Encrypt configuration by following the %{docs_link_start}documentation on GitLab Pages%{docs_link_end}.").html_safe % { docs_link_url: docs_link_url, docs_link_start: docs_link_start, docs_link_end: docs_link_end }

doc/administration/pages/index.md

@@ -265,6 +265,23 @@ verification requirement. Navigate to `Admin area ➔ Settings` and uncheck
 **Require users to prove ownership of custom domains** in the Pages section.
 This setting is enabled by default.
 
+### Let's Encrypt integration
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/28996) in GitLab 12.1.
+
+[GitLab Pages' Let's Encrypt integration](../../user/project/pages/custom_domains_ssl_tls_certification/lets_encrypt_integration.md)
+allows users to add Let's Encrypt SSL certificates for GitLab Pages
+sites served under a custom domain.
+
+To enable it, you'll need to:
+
+1. Choose an email on which you will recieve notifications about expiring domains.
+1. Navigate to your instance's **Admin Area > Settings > Preferences** and expand **Pages** settings.
+1. Enter the email for receiving notifications and accept Let's Encrypt's Terms of Service as shown below.
+1. Click **Save changes**.
+
+![Let's Encrypt settings](img/lets_encrypt_integration_v12_1.png)
+
 ### Access control
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/33422) in GitLab 11.5.

doc/user/project/pages/custom_domains_ssl_tls_certification/index.md

@@ -204,6 +204,14 @@ can use the following setup:
 
 Read this document for an [overview on SSL/TLS certification](ssl_tls_concepts.md).
 
+To secure your custom domain with GitLab Pages you can opt by:
+
+- Using the [Let's Encrypt integration with GitLab Pages](lets_encrypt_integration.md),
+  which automatically obtains and renews SSL certificates
+  for your Pages domains.
+- Manually adding SSL/TLS certificates to GitLab Pages websites
+  by following the steps below.
+
 ### Requirements
 
 - A GitLab Pages website up and running accessible via a custom domain.
@@ -255,6 +263,7 @@ To enable this setting:
 1. Navigate to your project's **Settings > Pages**.
 1. Tick the checkbox **Force HTTPS (requires valid certificates)**.
 
+
 <!-- ## Troubleshooting
 
 Include any troubleshooting steps that you can foresee. If you know beforehand what issues

doc/user/project/pages/custom_domains_ssl_tls_certification/lets_encrypt_integration.md

+---
+type: reference
+description: "Automatic Let's Encrypt SSL certificates for GitLab Pages."
+---
+
+# GitLab Pages integration with Let's Encrypt
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/28996) in GitLab 12.1.
+
+The GitLab Pages integration with Let's Encrypt (LE) allows you
+to use LE certificates for your Pages website with custom domains
+without the hassle of having to issue and update them yourself;
+GitLab does it for you, out-of-the-box.
+
+[Let's Encrypt](https://letsencrypt.org) is a free, automated, and
+open source Certificate Authority.
+
+## Requirements
+
+Before you can enable automatic provisioning of a SSL certificate for your domain, make sure you have:
+
+- Created a [project](../getting_started_part_two.md) in GitLab
+  containing your website's source code.
+- Acquired a domain (`example.com`) and added a [DNS entry](index.md)
+  pointing it to your Pages website.
+- [Added your domain to your Pages project](index.md#1-add-a-custom-domain-to-pages)
+  and verified your ownership.
+- Have your website up and running, accessible through your custom domain.
+
+NOTE: **Note:**
+GitLab's Let's Encrypt integration is enabled and available on GitLab.com.
+For **self-managed** GitLab instances, make sure your administrator has
+[enabled it](../../../../administration/pages/index.md#lets-encrypt-integration).
+
+## Enabling Let's Encrypt integration for your custom domain
+
+Once you've met the requirements, to enable Let's Encrypt integration:
+
+1. Navigate to your project's **Settings > Pages**.
+1. Find your domain and click **Details**.
+1. Click **Edit** in the top-right corner.
+1. Enable Let's Encrypt integration by switching **Automatic certificate management using Let's Encrypt**:
+
+    ![Enable Let's Encrypt](img/lets_encrypt_integration_v12_1.png)
+
+1. Click **Save changes**.
+
+Once enabled, GitLab will obtain a LE certificate and add it to the
+associated Pages domain. It will be also renewed automatically by GitLab.
+
+> **Notes:**
+>
+> - Issuing the certificate and updating Pages configuration
+>   **can take up to an hour**.
+> - If you already have SSL certificate in domain settings it
+>   will continue to work until it will be replaced by Let's Encrypt's certificate.
+
+<!-- ## Troubleshooting
+
+Include any troubleshooting steps that you can foresee. If you know beforehand what issues
+one might have when setting this up, or when something is changed, or on upgrading, it's
+important to describe those, too. Think of things that may go wrong and include them here.
+This is important to minimize requests for support, and to avoid doc comments with
+questions that you know someone might ask.
+
+Each scenario can be a third-level heading, e.g. `### Getting error message X`.
+If you have none to add when creating a doc, leave this section in place
+but commented out to help encourage others to add to it in the future. -->

doc/user/project/pages/index.md

@@ -143,8 +143,8 @@ To learn more about configuration options for GitLab Pages, read the following:
 | [Exploring GitLab Pages](introduction.md) | Requirements, technical aspects, specific GitLab CI's configuration options, Access Control, custom 404 pages, limitations, FAQ. |
 |---+---|
 | [Custom domains and SSL/TLS Certificates](custom_domains_ssl_tls_certification/index.md) | How to add custom domains and subdomains to your website, configure DNS records and SSL/TLS certificates. |
+| [Let's Encrypt integration](custom_domains_ssl_tls_certification/lets_encrypt_integration.md) | Secure your Pages sites with Let's Encrypt certificates automatically obtained and renewed by GitLab. |
 | [CloudFlare certificates](https://about.gitlab.com/2017/02/07/setting-up-gitlab-pages-with-cloudflare-certificates/) | Secure your Pages site with CloudFlare certificates. |
-| [Let's Encrypt certificates](lets_encrypt_for_gitlab_pages.md) | Secure your Pages site with Let's Encrypt certificates. |
 |---+---|
 | [Static vs dynamic websites](https://about.gitlab.com/2016/06/03/ssg-overview-gitlab-pages-part-1-dynamic-x-static/) | A conceptual overview on static versus dynamic sites. |
 | [Modern static site generators](https://about.gitlab.com/2016/06/10/ssg-overview-gitlab-pages-part-2/) | A conceptual overview on SSGs. |

doc/user/project/pages/lets_encrypt_for_gitlab_pages.md

 ---
-description: "How to secure GitLab Pages websites with Let's Encrypt."
+description: "How to secure GitLab Pages websites with Let's Encrypt (manual process, deprecated)."
 type: howto
-last_updated: 2019-06-04
+last_updated: 2019-07-15
 ---
 
-# Let's Encrypt for GitLab Pages
+# Let's Encrypt for GitLab Pages (manual process, deprecated)
+
+CAUTION: **Warning:**
+This method is still valid but was **deprecated** in favor of the
+[Let's Encrypt integration](custom_domains_ssl_tls_certification/lets_encrypt_integration.md)
+introduced in GitLab 12.1.
 
 If you have a GitLab Pages website served under your own domain,
 you might want to secure it with a SSL/TSL certificate.