Add auto SSL toggle to Pages domain settings page

This commit adds an auto SSL toggle switch to the settings page of
GitLab Pages domains.  This toggle enable or disabled auto SSL
management via Let's Encrypt.  Toggling the button dynamically
updates the form using client-side JavaScript.  All changes are behind
feature flags.

4 files changed, 80 insertions, 18 deletions

diff --git a/app/views/projects/pages_domains/_form.html.haml b/app/views/projects/pages_domains/_form.html.haml
index 1e50a101c1e..33f2166480b 100644
--- a/app/views/projects/pages_domains/_form.html.haml
+++ b/app/views/projects/pages_domains/_form.html.haml
@@ -1,29 +1,80 @@
 - if @domain.errors.any?
-  #error_explanation
-    .alert.alert-danger
-      - @domain.errors.full_messages.each do |msg|
-        %p= msg
+  .alert.alert-danger
+    - @domain.errors.full_messages.each do |msg|
+      = msg
 
 .form-group.row
   .col-sm-2.col-form-label
     = f.label :domain, _("Domain")
   .col-sm-10
-    = f.text_field :domain, required: true, autocomplete: 'off', class: 'form-control', disabled: @domain.persisted?
+    = f.text_field :domain, required: true, autocomplete: "off", class: "form-control", disabled: @domain.persisted?
 
 - if Gitlab.config.pages.external_https
-  .form-group.row
-    .col-sm-2.col-form-label
-      = f.label :certificate, _("Certificate (PEM)")
-    .col-sm-10
-      = f.text_area :certificate, rows: 5, class: 'form-control'
-      %span.help-inline= _("Upload a certificate for your domain with all intermediates")
-
-  .form-group.row
-    .col-sm-2.col-form-label
-      = f.label :key, _("Key (PEM)")
-    .col-sm-10
-      = f.text_area :key, rows: 5, class: 'form-control'
-      %span.help-inline= _("Upload a private key for your certificate")
+
+  - auto_ssl_available = Feature.enabled?(:pages_auto_ssl)
+  - auto_ssl_enabled = @domain.auto_ssl_enabled?
+  - auto_ssl_available_and_enabled = auto_ssl_available && auto_ssl_enabled
+
+  - if auto_ssl_available
+    .form-group.row
+      .col-sm-2.col-form-label
+        %label{ for: "pages_domain_auto_ssl_enabled_button" }
+          - lets_encrypt_link_url = "https://letsencrypt.org/"
+          - lets_encrypt_link_start = "<a href=\"%{lets_encrypt_link_url}\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"text-nowrap\">".html_safe % { lets_encrypt_link_url: lets_encrypt_link_url }
+          - lets_encrypt_link_end = "</a>".html_safe
+          = _("Automatic certificate management using %{lets_encrypt_link_start}Let's Encrypt%{lets_encrypt_link_end}").html_safe % { lets_encrypt_link_start: lets_encrypt_link_start, lets_encrypt_link_end: lets_encrypt_link_end }
+
+      .col-sm-10.js-auto-ssl-toggle-container
+        %button{ type: "button", id: "pages_domain_auto_ssl_enabled_button",
+          class: "js-project-feature-toggle project-feature-toggle mt-2 #{"is-checked" if auto_ssl_available_and_enabled}",
+          "aria-label": _("Automatic certificate management using Let's Encrypt") }
+          = f.hidden_field :auto_ssl_enabled?, class: "js-project-feature-toggle-input"
+          %span.toggle-icon
+            = 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_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 }
+
+  .js-shown-if-auto-ssl{ class: ("d-none" unless auto_ssl_available_and_enabled) }
+    .form-group.row
+      .col-sm-2.col-form-label
+        = f.label :certificate, _("Certificate (PEM)")
+      .col-sm-10
+        - if auto_ssl_available_and_enabled && !@domain.certificate.empty?
+          = f.text_area :certificate,
+            rows: 5,
+            class: "form-control",
+            disabled: true
+          %span.help-inline.text-muted= _("This certificate is automatically managed by Let's Encrypt")
+        - else
+          %p.text-secondary.form-control-plaintext= _("The certificate will be shown here once it has been obtained from Let's Encrypt. This process may take up to an hour to complete.")
+
+  .js-shown-unless-auto-ssl{ class: ("d-none" if auto_ssl_available_and_enabled) }
+    .form-group.row
+      .col-sm-2.col-form-label
+        = f.label :certificate, _("Certificate (PEM)")
+      .col-sm-10
+        = f.text_area :certificate,
+          rows: 5,
+          class: "form-control js-enabled-unless-auto-ssl",
+          value: (@domain.certificate unless auto_ssl_available_and_enabled),
+          disabled: auto_ssl_available_and_enabled
+        %span.help-inline.text-muted= _("Upload a certificate for your domain with all intermediates")
+
+    .form-group.row
+      .col-sm-2.col-form-label
+        = f.label :key, _("Key (PEM)")
+      .col-sm-10
+        = f.text_area :key,
+          rows: 5,
+          class: "form-control js-enabled-unless-auto-ssl",
+          value: (@domain.key unless auto_ssl_available_and_enabled),
+          disabled: auto_ssl_available_and_enabled
+        %span.help-inline.text-muted= _("Upload a private key for your certificate")
+
 - else
   .nothing-here-block
     = _("Support for custom certificates is disabled. Ask your system's administrator to enable it.")
diff --git a/app/views/projects/pages_domains/_helper_text.html.haml b/app/views/projects/pages_domains/_helper_text.html.haml
new file mode 100644
index 00000000000..5a79fefabfc
--- /dev/null
+++ b/app/views/projects/pages_domains/_helper_text.html.haml
@@ -0,0 +1,9 @@
+- docs_link_url = help_page_path("user/project/pages/getting_started_part_three.md", anchor: "adding-certificates-to-your-project")
+- 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
+
+-# Hiding behind a feature flag to avoid any changes to this feature's implemention
+-# when the :pages_auto_ssl feature flag is disabled.  This check should be removed
+-# once the :pages_auto_ssl feature flag is removed.
+- if Feature.enabled?(:pages_auto_ssl)
+  %p= _("Learn more about adding certificates to your project 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 }
diff --git a/app/views/projects/pages_domains/edit.html.haml b/app/views/projects/pages_domains/edit.html.haml
index e11387ae742..7c0777e5496 100644
--- a/app/views/projects/pages_domains/edit.html.haml
+++ b/app/views/projects/pages_domains/edit.html.haml
@@ -3,6 +3,7 @@
 - page_title @domain.domain
 %h3.page-title
   = @domain.domain
+= render 'projects/pages_domains/helper_text'
 %hr.clearfix
 %div
   = form_for [@project.namespace.becomes(Namespace), @project, @domain], html: { class: 'fieldset-form' } do |f|
diff --git a/app/views/projects/pages_domains/new.html.haml b/app/views/projects/pages_domains/new.html.haml
index c7cefa87c76..e23ccb5d4c6 100644
--- a/app/views/projects/pages_domains/new.html.haml
+++ b/app/views/projects/pages_domains/new.html.haml
@@ -2,6 +2,7 @@
 - page_title _('New Pages Domain')
 %h3.page-title
   = _("New Pages Domain")
+= render 'projects/pages_domains/helper_text'
 %hr.clearfix
 %div
   = form_for [@project.namespace.becomes(Namespace), @project, @domain], html: { class: 'fieldset-form' } do |f|