Add an option to easily disable disk-cache (#7928)

Merge pull request 7928

docs/_docs/configuration/options.md

@@ -43,13 +43,35 @@ class="flag">flags</code> (specified on the command-line) that control them.
     <tr class="setting">
       <td>
         <p class="name"><strong>Safe</strong></p>
-        <p class="description">Disable <a href="/docs/plugins/">custom plugins, and ignore symbolic links</a>.</p>
+        <p class="description">
+          Disable <a href="/docs/plugins/">custom plugins</a>, caching to disk
+          and ignore symbolic links.
+        </p>
       </td>
       <td class="align-center">
         <p><code class="option">safe: BOOL</code></p>
         <p><code class="flag">--safe</code></p>
       </td>
     </tr>
+    <tr class="setting">
+      <td>
+        <p class="name">
+          <strong>Disable Disk Cache</strong>
+          <span class="version-badge" title="Introduced in v4.1.0">4.1.0</span>
+        </p>
+        <p class="description">
+          Disable caching of content to disk in order to skip creating a
+          <code>.jekyll-cache</code> or similar directory at the source
+          to avoid interference with virtual environments and third-party
+          directory watchers.
+          Caching to disk is always disabled in <code>safe</code> mode.
+        </p>
+      </td>
+      <td class="align-center">
+        <p><code class="option">disable_disk_cache: BOOL</code></p>
+        <p><code class="flag">--disable-disk-cache</code></p>
+      </td>
+    </tr>
     <tr class="setting">
       <td>
         <p class="name"><strong>Exclude</strong></p>

features/cache.feature

@@ -35,3 +35,12 @@ Feature: Cache
     But the .jekyll-cache directory should not exist
     And the _site directory should exist
     And I should see "<p>Hello World</p>" in "_site/index.html"
+
+  Scenario: Disabling disk usage in non-safe mode
+    Given I have an "index.md" page that contains "{{ site.title }}"
+    And I have a configuration file with "title" set to "Hello World"
+    When I run jekyll build --disable-disk-cache
+    Then I should get a zero exit status
+    And the _site directory should exist
+    And I should see "<p>Hello World</p>" in "_site/index.html"
+    But the .jekyll-cache directory should not exist

lib/jekyll/command.rb

@@ -67,6 +67,8 @@ module Jekyll
         cmd.option "show_drafts", "-D", "--drafts", "Render posts in the _drafts folder"
         cmd.option "unpublished", "--unpublished",
                    "Render posts that were marked as unpublished"
+        cmd.option "disable_disk_cache", "--disable-disk-cache",
+                   "Disable caching to disk in non-safe mode"
         cmd.option "quiet", "-q", "--quiet", "Silence output."
         cmd.option "verbose", "-V", "--verbose", "Print verbose output."
         cmd.option "incremental", "-I", "--incremental", "Enable incremental rebuild."

lib/jekyll/site.rb

@@ -470,7 +470,7 @@ module Jekyll
     # Disable Marshaling cache to disk in Safe Mode
     def configure_cache
       Jekyll::Cache.cache_dir = in_source_dir(config["cache_dir"], "Jekyll/Cache")
-      Jekyll::Cache.disable_disk_cache! if safe
+      Jekyll::Cache.disable_disk_cache! if safe || config["disable_disk_cache"]
     end
 
     def configure_plugins