The preview server can now serve over HTTPS using the `--https` flag. It will use an automatic self-signed cert which can be overridden using `--ssl_certificate` and `--ssl_private_key`. These settings can also be set in `config.rb`.

CHANGELOG.md

@@ -1,6 +1,8 @@
 master
 ===
 
+* The preview server can now serve over HTTPS using the `--https` flag. It will use an automatic self-signed cert which can be overridden using `--ssl_certificate` and `--ssl_private_key`. These settings can also be set in `config.rb`
+
 3.3.11
 ===
 * Add `srcset` option to `image_tag`. Also enables them in Markdown.
@@ -22,7 +24,7 @@ master
 3.3.8
 ===
 * Define a mime type for sourcemaps. #1451
-* Asset hashing for image references in srcset 
+* Asset hashing for image references in srcset
 * Import patch to bugfix from Padrino Helpers #1401
 * Better URI encoding and decoding #1406
 * Update version of i18n

middleman-core/lib/middleman-core/application.rb

@@ -75,6 +75,18 @@ module Middleman
     # @return [Fixnum]
     config.define_setting :port, 4567, 'The preview server port'
 
+    # Whether to serve the preview server over HTTPS.
+    # @return [Boolean]
+    config.define_setting :https, false, 'Serve the preview server over SSL/TLS'
+
+    # The (optional) path to the SSL cert to use for the preview server.
+    # @return [String]
+    config.define_setting :ssl_certificate, nil, 'Path to an X.509 certificate to use for the preview server'
+
+    # The (optional) private key for the certificate in :ssl_certificate.
+    # @return [String]
+    config.define_setting :ssl_private_key, nil, "Path to an RSA private key for the preview server's certificate"
+
     # Name of the source directory
     # @return [String]
     config.define_setting :source,      'source', 'Name of the source directory'

middleman-core/lib/middleman-core/cli/server.rb

@@ -18,6 +18,13 @@ module Middleman::Cli
     method_option :port,
                   aliases: '-p',
                   desc: 'The port Middleman will listen on'
+    method_option :https,
+                  type: :boolean,
+                  desc: 'Serve the preview server over SSL/TLS'
+    method_option :ssl_certificate,
+                  desc: 'Path to an X.509 certificate to use for the preview server'
+    method_option :ssl_private_key,
+                  desc: "Path to an RSA private key for the preview server's certificate"
     method_option :verbose,
                   type: :boolean,
                   default: false,
@@ -63,6 +70,9 @@ module Middleman::Cli
       params = {
         port: options['port'],
         host: options['host'],
+        https: options['https'],
+        ssl_certificate: options['ssl_certificate'],
+        ssl_private_key: options['ssl_private_key'],
         environment: options['environment'],
         debug: options['verbose'],
         instrumenting: options['instrument'],

middleman-core/lib/middleman-core/preview_server.rb

@@ -1,4 +1,6 @@
 require 'webrick'
+require 'webrick/https'
+require 'openssl'
 require 'middleman-core/meta_pages'
 require 'middleman-core/logger'
 
@@ -6,17 +8,22 @@ require 'middleman-core/logger'
 module Middleman
   module PreviewServer
     class << self
-      attr_reader :app, :host, :port
+      attr_reader :app, :host, :port, :ssl_certificate, :ssl_private_key
       delegate :logger, to: :app
 
+      def https?
+        @https
+      end
+
       # Start an instance of Middleman::Application
       # @return [void]
       def start(opts={})
         @options = opts
 
         mount_instance(new_app)
-        logger.info "== The Middleman is standing watch at http://#{host}:#{port}"
-        logger.info "== Inspect your site configuration at http://#{host}:#{port}/__middleman/"
+        scheme = https? ? 'https' : 'http'
+        logger.info "== The Middleman is standing watch at #{scheme}://#{host}:#{port}"
+        logger.info "== Inspect your site configuration at #{scheme}://#{host}:#{port}/__middleman/"
 
         @initialized ||= false
         return if @initialized
@@ -106,10 +113,17 @@ module Middleman
           config[:environment] = opts[:environment].to_sym if opts[:environment]
           config[:host] = opts[:host] if opts[:host]
           config[:port] = opts[:port] if opts[:port]
+          config[:https] = opts[:https] unless opts[:https].nil?
+          config[:ssl_certificate] = opts[:ssl_certificate] if opts[:ssl_certificate]
+          config[:ssl_private_key] = opts[:ssl_private_key] if opts[:ssl_private_key]
         end
 
         @host = @app.config[:host]
         @port = @app.config[:port]
+        @https = @app.config[:https]
+
+        @ssl_certificate = @app.config[:ssl_certificate]
+        @ssl_private_key = @app.config[:ssl_private_key]
 
         @app
       end
@@ -173,6 +187,22 @@ module Middleman
           DoNotReverseLookup: true
         }
 
+        if https?
+          http_opts[:SSLEnable] = true
+
+          if ssl_certificate || ssl_private_key
+            raise "You must provide both :ssl_certificate and :ssl_private_key" unless ssl_private_key && ssl_certificate
+            http_opts[:SSLCertificate] = OpenSSL::X509::Certificate.new File.read ssl_certificate
+            http_opts[:SSLPrivateKey] = OpenSSL::PKey::RSA.new File.read ssl_private_key
+          else
+            # use a generated self-signed cert
+            http_opts[:SSLCertName] = [
+                                       %w(CN localhost),
+                                       %w(CN #{host})
+                                      ].uniq
+          end
+        end
+
         if is_logging
           http_opts[:Logger] = FilteredWebrickLog.new
         else