Make ASt previewer/analyzer binary paths configurable

activestorage/lib/active_storage/analyzer/video_analyzer.rb

@@ -19,6 +19,8 @@ module ActiveStorage
   # This analyzer requires the {ffmpeg}[https://www.ffmpeg.org] system library, which is not provided by Rails. You must
   # install ffmpeg yourself to use this analyzer.
   class Analyzer::VideoAnalyzer < Analyzer
+    class_attribute :ffprobe_path, default: "ffprobe"
+
     def self.accept?(blob)
       blob.video?
     end
@@ -68,7 +70,7 @@ def probe
       end
 
       def probe_from(file)
-        IO.popen([ "ffprobe", "-print_format", "json", "-show_streams", "-v", "error", file.path ]) do |output|
+        IO.popen([ ffprobe_path, "-print_format", "json", "-show_streams", "-v", "error", file.path ]) do |output|
           JSON.parse(output.read)
         end
       rescue Errno::ENOENT

activestorage/lib/active_storage/engine.rb

@@ -15,7 +15,8 @@ class Engine < Rails::Engine # :nodoc:
 
     config.active_storage = ActiveSupport::OrderedOptions.new
     config.active_storage.previewers = [ ActiveStorage::Previewer::PDFPreviewer, ActiveStorage::Previewer::VideoPreviewer ]
-    config.active_storage.analyzers  = [ ActiveStorage::Analyzer::ImageAnalyzer, ActiveStorage::Analyzer::VideoAnalyzer ]
+    config.active_storage.analyzers = [ ActiveStorage::Analyzer::ImageAnalyzer, ActiveStorage::Analyzer::VideoAnalyzer ]
+    config.active_storage.paths = ActiveSupport::OrderedOptions.new
 
     config.eager_load_namespaces << ActiveStorage
 
@@ -68,5 +69,21 @@ class Engine < Rails::Engine # :nodoc:
         end
       end
     end
+
+    initializer "active_storage.paths" do
+      config.after_initialize do |app|
+        if ffprobe_path = app.config.active_storage.paths.ffprobe
+          ActiveStorage::Analyzer::VideoAnalyzer.ffprobe_path = ffprobe_path
+        end
+
+        if ffmpeg_path = app.config.active_storage.paths.ffmpeg
+          ActiveStorage::Previewer::VideoPreviewer.ffmpeg_path = ffmpeg_path
+        end
+
+        if mutool_path = app.config.active_storage.paths.mutool
+          ActiveStorage::Previewer::PDFPreviewer.mutool_path = mutool_path
+        end
+      end
+    end
   end
 end

activestorage/lib/active_storage/previewer/pdf_previewer.rb

@@ -2,16 +2,23 @@
 
 module ActiveStorage
   class Previewer::PDFPreviewer < Previewer
+    class_attribute :mutool_path, default: "mutool"
+
     def self.accept?(blob)
       blob.content_type == "application/pdf"
     end
 
     def preview
       download_blob_to_tempfile do |input|
-        draw "mutool", "draw", "-F", "png", "-o", "-", input.path, "1" do |output|
+        draw_first_page_from input do |output|
           yield io: output, filename: "#{blob.filename.base}.png", content_type: "image/png"
         end
       end
     end
+
+    private
+      def draw_first_page_from(file, &block)
+        draw mutool_path, "draw", "-F", "png", "-o", "-", file.path, "1", &block
+      end
   end
 end

activestorage/lib/active_storage/previewer/video_previewer.rb

@@ -2,6 +2,8 @@
 
 module ActiveStorage
   class Previewer::VideoPreviewer < Previewer
+    class_attribute :ffmpeg_path, default: "ffmpeg"
+
     def self.accept?(blob)
       blob.video?
     end
@@ -16,7 +18,7 @@ def preview
 
     private
       def draw_relevant_frame_from(file, &block)
-        draw "ffmpeg", "-i", file.path, "-y", "-vcodec", "png",
+        draw ffmpeg_path, "-i", file.path, "-y", "-vcodec", "png",
           "-vf", "thumbnail", "-vframes", "1", "-f", "image2", "-", &block
       end
   end