Add option to fail a build with front matter syntax errors (#5832)

Merge pull request 5832

docs/_docs/configuration.md

@@ -305,6 +305,18 @@ class="flag">flags</code> (specified on the command-line) that control them.
         <p><code class="flag">--profile</code></p>
       </td>
     </tr>
+    <tr class="setting">
+      <td>
+        <p class="name"><strong>Strict Front Matter</strong></p>
+        <p class="description">
+            Cause a build to fail if there is a YAML syntax error in a page's front matter.
+        </p>
+      </td>
+      <td class="align-center">
+        <p><code class="option">strict_front_matter: BOOL</code></p>
+        <p><code class="flag">--strict_front_matter</code></p>
+      </td>
+    </tr>
   </tbody>
 </table>
 </div>
@@ -601,12 +613,13 @@ collections:
     output:   true
 
 # Handling Reading
-safe:         false
+safe:                 false
-include:      [".htaccess"]
+include:              [".htaccess"]
-exclude:      ["Gemfile", "Gemfile.lock", "node_modules", "vendor/bundle/", "vendor/cache/", "vendor/gems/", "vendor/ruby/"]
+exclude:              ["Gemfile", "Gemfile.lock", "node_modules", "vendor/bundle/", "vendor/cache/", "vendor/gems/", "vendor/ruby/"]
-keep_files:   [".git", ".svn"]
+keep_files:           [".git", ".svn"]
-encoding:     "utf-8"
+encoding:             "utf-8"
-markdown_ext: "markdown,mkdown,mkdn,mkd,md"
+markdown_ext:         "markdown,mkdown,mkdn,mkd,md"
+strict_front_matter: false
 
 # Filtering Content
 show_drafts: null

lib/jekyll/command.rb

@@ -46,6 +46,7 @@ module Jekyll
       # c - the Jekyll::Command to add these options to
       #
       # Returns nothing
+      # rubocop:disable Metrics/MethodLength
       def add_build_options(c)
         c.option "config", "--config CONFIG_FILE[,CONFIG_FILE2,...]",
           Array, "Custom configuration file"
@@ -66,7 +67,10 @@ module Jekyll
         c.option "quiet", "-q", "--quiet", "Silence output."
         c.option "verbose", "-V", "--verbose", "Print verbose output."
         c.option "incremental", "-I", "--incremental", "Enable incremental rebuild."
+        c.option "strict_front_matter", "--strict_front_matter",
+          "Fail if errors are present in front matter"
       end
+      # rubocop:enable Metrics/MethodLength
     end
   end
 end

lib/jekyll/configuration.rb

@@ -6,71 +6,72 @@ module Jekyll
     # Strings rather than symbols are used for compatibility with YAML.
     DEFAULTS = Configuration[{
       # Where things are
-      "source"            => Dir.pwd,
+      "source"              => Dir.pwd,
-      "destination"       => File.join(Dir.pwd, "_site"),
+      "destination"         => File.join(Dir.pwd, "_site"),
-      "plugins_dir"       => "_plugins",
+      "plugins_dir"         => "_plugins",
-      "layouts_dir"       => "_layouts",
+      "layouts_dir"         => "_layouts",
-      "data_dir"          => "_data",
+      "data_dir"            => "_data",
-      "includes_dir"      => "_includes",
+      "includes_dir"        => "_includes",
-      "collections"       => {},
+      "collections"         => {},
 
       # Handling Reading
-      "safe"              => false,
+      "safe"                => false,
-      "include"           => [".htaccess"],
+      "include"             => [".htaccess"],
-      "exclude"           => %w(
+      "exclude"             => %w(
         Gemfile Gemfile.lock node_modules vendor/bundle/ vendor/cache/ vendor/gems/
         vendor/ruby/
       ),
-      "keep_files"        => [".git", ".svn"],
+      "keep_files"          => [".git", ".svn"],
-      "encoding"          => "utf-8",
+      "encoding"            => "utf-8",
-      "markdown_ext"      => "markdown,mkdown,mkdn,mkd,md",
+      "markdown_ext"        => "markdown,mkdown,mkdn,mkd,md",
+      "strict_front_matter" => false,
 
       # Filtering Content
-      "show_drafts"       => nil,
+      "show_drafts"         => nil,
-      "limit_posts"       => 0,
+      "limit_posts"         => 0,
-      "future"            => false,
+      "future"              => false,
-      "unpublished"       => false,
+      "unpublished"         => false,
 
       # Plugins
-      "whitelist"         => [],
+      "whitelist"           => [],
-      "plugins"           => [],
+      "plugins"             => [],
 
       # Conversion
-      "markdown"          => "kramdown",
+      "markdown"            => "kramdown",
-      "highlighter"       => "rouge",
+      "highlighter"         => "rouge",
-      "lsi"               => false,
+      "lsi"                 => false,
-      "excerpt_separator" => "\n\n",
+      "excerpt_separator"   => "\n\n",
-      "incremental"       => false,
+      "incremental"         => false,
 
       # Serving
-      "detach"            => false, # default to not detaching the server
+      "detach"              => false, # default to not detaching the server
-      "port"              => "4000",
+      "port"                => "4000",
-      "host"              => "127.0.0.1",
+      "host"                => "127.0.0.1",
-      "baseurl"           => "",
+      "baseurl"             => "",
-      "show_dir_listing"  => false,
+      "show_dir_listing"    => false,
 
       # Output Configuration
-      "permalink"         => "date",
+      "permalink"           => "date",
-      "paginate_path"     => "/page:num",
+      "paginate_path"       => "/page:num",
-      "timezone"          => nil, # use the local timezone
+      "timezone"            => nil, # use the local timezone
 
-      "quiet"             => false,
+      "quiet"               => false,
-      "verbose"           => false,
+      "verbose"             => false,
-      "defaults"          => [],
+      "defaults"            => [],
 
-      "liquid"            => {
+      "liquid"              => {
         "error_mode" => "warn",
       },
 
-      "rdiscount"         => {
+      "rdiscount"           => {
         "extensions" => [],
       },
 
-      "redcarpet"         => {
+      "redcarpet"           => {
         "extensions" => [],
       },
 
-      "kramdown"          => {
+      "kramdown"            => {
         "auto_ids"      => true,
         "toc_levels"    => "1..6",
         "entity_output" => "as_char",

lib/jekyll/convertible.rb

@@ -48,8 +48,10 @@ module Jekyll
         end
       rescue SyntaxError => e
         Jekyll.logger.warn "YAML Exception reading #{filename}: #{e.message}"
+        raise e if self.site.config["strict_front_matter"]
       rescue => e
         Jekyll.logger.warn "Error reading file #{filename}: #{e.message}"
+        raise e if self.site.config["strict_front_matter"]
       end
 
       self.data ||= {}

lib/jekyll/document.rb

@@ -259,11 +259,8 @@ module Jekyll
           merge_defaults
           read_content(opts)
           read_post_data
-        rescue SyntaxError => e
-          Jekyll.logger.error "Error:", "YAML Exception reading #{path}: #{e.message}"
         rescue => e
-          raise e if e.is_a? Jekyll::Errors::FatalException
+          handle_read_error(e)
-          Jekyll.logger.error "Error:", "could not read file #{path}: #{e.message}"
         end
       end
     end
@@ -457,6 +454,19 @@ module Jekyll
       generate_excerpt
     end
 
+    private
+    def handle_read_error(error)
+      if error.is_a? SyntaxError
+        Jekyll.logger.error "Error:", "YAML Exception reading #{path}: #{error.message}"
+      else
+        Jekyll.logger.error "Error:", "could not read file #{path}: #{error.message}"
+      end
+
+      if site.config["strict_front_matter"] || error.is_a?(Jekyll::Errors::FatalException)
+        raise error
+      end
+    end
+
     private
     def populate_title
       if relative_path =~ DATE_FILENAME_MATCHER

test/source/_broken/bad_post.md

@@ -0,0 +1,4 @@
+---
+bad yaml: [
+---
+Real content starts here

test/test_convertible.rb

@@ -33,6 +33,14 @@ class TestConvertible < JekyllUnitTest
       assert_match(%r!#{File.join(@base, name)}!, out)
     end
 
+    should "raise for broken front matter with `strict_front_matter` set" do
+      name = "broken_front_matter2.erb"
+      @convertible.site.config["strict_front_matter"] = true
+      assert_raises do
+        @convertible.read_yaml(@base, name)
+      end
+    end
+
     should "not allow ruby objects in YAML" do
       out = capture_stderr do
         @convertible.read_yaml(@base, "exploit_front_matter.erb")

test/test_site.rb

@@ -280,6 +280,24 @@ class TestSite < JekyllUnitTest
           Site.new(site_configuration("destination" => File.join(source_dir, "..")))
         end
       end
+
+      should "raise for bad frontmatter if strict_front_matter is set" do
+        site = Site.new(site_configuration(
+          "collections"         => ["broken"],
+          "strict_front_matter" => true
+        ))
+        assert_raises do
+          site.process
+        end
+      end
+
+      should "not raise for bad frontmatter if strict_front_matter is not set" do
+        site = Site.new(site_configuration(
+          "collections"         => ["broken"],
+          "strict_front_matter" => false
+        ))
+        site.process
+      end
     end
 
     context "with orphaned files in destination" do