add disk space usage failsafe

app/models/admin_dashboard_data.rb

@@ -40,7 +40,8 @@ class AdminDashboardData
       site_description_check,
       access_password_removal,
       site_contact_username_check,
-      notification_email_check ].compact
+      notification_email_check,
+    ].compact
   end
 
   def self.fetch_stats
@@ -147,7 +148,7 @@ class AdminDashboardData
   end
 
   def site_description_check
-    return I18n.t('dashboard.site_description_missing') if !SiteSetting.site_description.present?
+    I18n.t('dashboard.site_description_missing') if !SiteSetting.site_description.present?
   end
 
   def send_consumer_email_check
@@ -166,7 +167,6 @@ class AdminDashboardData
     I18n.t('dashboard.ruby_version_warning') if RUBY_VERSION == '2.0.0' and RUBY_PATCHLEVEL < 247
   end
 
-
   # TODO: generalize this method of putting i18n keys with expiry in redis
   #       that should be reported on the admin dashboard:
   def access_password_removal

app/models/site_setting.rb

@@ -15,7 +15,6 @@ class SiteSetting < ActiveRecord::Base
     end
   end
 
-
   def self.call_discourse_hub?
     self.enforce_global_nicknames? && self.discourse_org_access_key.present?
   end

config/locales/server.en.yml

@@ -500,7 +500,8 @@ en:
     company_domain: "The domain name owned by the company that runs this site, used in legal documents like the /tos"
     queue_jobs: "DEVELOPER ONLY! WARNING! By default, queue jobs in sidekiq. If disabled, your site will be broken."
     crawl_images: "Enable retrieving images from third party sources to insert width and height dimensions"
-    download_remote_images_to_local: "Download a copy of all remote images"
+    download_remote_images_to_local: "Download a copy of remote images hotlinked in posts"
+    download_remote_images_threshold: "Amount of minimum available disk space required to download remote images locally (in percent)"
     ninja_edit_window: "Number of seconds after posting where edits do not create a new version"
     edit_history_visible_to_public: "Allow everyone to see previous versions of an edited post. When disabled, only staff members can view edit history."
     delete_removed_posts_after: "Number of hours after which posts removed by the author will be deleted."

config/site_settings.yml

@@ -253,6 +253,8 @@ files:
     default:
       test: false
       default: true
+  download_remote_images_threshold:
+    default: 20
 
 trust:
   default_trust_level: 0

lib/cooked_post_processor.rb

@@ -221,6 +221,8 @@ class CookedPostProcessor
   def pull_hotlinked_images
     # is the job enabled?
     return unless SiteSetting.download_remote_images_to_local?
+    # have we enough disk space?
+    return if disable_if_low_on_disk_space
     # we only want to run the job whenever it's changed by a user
     return if @post.updated_by == Discourse.system_user
     # make sure no other job is scheduled
@@ -230,6 +232,18 @@ class CookedPostProcessor
     Jobs.enqueue_in(delay.seconds.to_i, :pull_hotlinked_images, post_id: @post.id)
   end
 
+  def disable_if_low_on_disk_space
+    if available_disk_space < SiteSetting.download_remote_images_threshold
+      SiteSetting.download_remote_images_to_local = false
+      return true
+    end
+    false
+  end
+
+  def available_disk_space
+    100 - `df -l . | tail -1 | tr -s ' ' | cut -d ' ' -f 5`.to_i
+  end
+
   def dirty?
     @dirty
   end

spec/components/cooked_post_processor_spec.rb

@@ -275,6 +275,8 @@ describe CookedPostProcessor do
     let(:post) { build(:post) }
     let(:cpp) { CookedPostProcessor.new(post) }
 
+    before { cpp.stubs(:available_disk_space).returns(90) }
+
     it "does not run when download_remote_images_to_local is disabled" do
       SiteSetting.stubs(:download_remote_images_to_local).returns(false)
       Jobs.expects(:cancel_scheduled_job).never
@@ -291,6 +293,13 @@ describe CookedPostProcessor do
         cpp.pull_hotlinked_images
       end
 
+      it "disables download when disk space is low" do
+        SiteSetting.expects(:download_remote_images_threshold).returns(20)
+        cpp.expects(:available_disk_space).returns(10)
+        Jobs.expects(:cancel_scheduled_job).never
+        cpp.pull_hotlinked_images
+      end
+
       context "and the post has been updated by a user" do
 
         before { post.id = 42 }
@@ -310,4 +319,25 @@ describe CookedPostProcessor do
 
   end
 
+  context ".disable_if_low_on_disk_space" do
+
+    let(:post) { build(:post) }
+    let(:cpp) { CookedPostProcessor.new(post) }
+
+    before { cpp.expects(:available_disk_space).returns(50) }
+
+    it "does nothing when there's enough disk space" do
+      SiteSetting.expects(:download_remote_images_threshold).returns(20)
+      SiteSetting.expects(:download_remote_images_to_local).never
+      cpp.disable_if_low_on_disk_space.should == false
+    end
+
+    it "disables download_remote_images_threshold when there's not enough disk space" do
+      SiteSetting.expects(:download_remote_images_threshold).returns(75)
+      cpp.disable_if_low_on_disk_space.should == true
+      SiteSetting.download_remote_images_to_local.should == false
+    end
+
+  end
+
 end