Active storage add proxying

actiontext/test/template/form_helper_test.rb

@@ -33,7 +33,7 @@ def form_with(*, **)
     assert_dom_equal \
       '<form action="/messages" accept-charset="UTF-8" data-remote="true" method="post">' \
         '<input type="hidden" name="message[content]" id="message_content_trix_input_message" />' \
-        '<trix-editor id="message_content" input="message_content_trix_input_message" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/:signed_id/:filename">' \
+        '<trix-editor id="message_content" input="message_content_trix_input_message" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/redirect/:signed_id/:filename">' \
         "</trix-editor>" \
       "</form>",
       output_buffer
@@ -47,7 +47,7 @@ def form_with(*, **)
     assert_dom_equal \
       '<form action="/messages" accept-charset="UTF-8" data-remote="true" method="post">' \
         '<input type="hidden" name="message[content]" id="message_content_trix_input_message" />' \
-        '<trix-editor id="message_content" input="message_content_trix_input_message" class="custom-class" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/:signed_id/:filename">' \
+        '<trix-editor id="message_content" input="message_content_trix_input_message" class="custom-class" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/redirect/:signed_id/:filename">' \
         "</trix-editor>" \
       "</form>",
       output_buffer
@@ -61,7 +61,7 @@ def form_with(*, **)
     assert_dom_equal \
       '<form action="/messages" accept-charset="UTF-8" data-remote="true" method="post">' \
         '<input type="hidden" name="message[not_an_attribute]" id="message_not_an_attribute_trix_input_message" />' \
-        '<trix-editor id="message_not_an_attribute" input="message_not_an_attribute_trix_input_message" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/:signed_id/:filename">' \
+        '<trix-editor id="message_not_an_attribute" input="message_not_an_attribute_trix_input_message" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/redirect/:signed_id/:filename">' \
         "</trix-editor>" \
       "</form>",
       output_buffer
@@ -75,7 +75,7 @@ def form_with(*, **)
     assert_dom_equal \
       '<form action="/messages" accept-charset="UTF-8" data-remote="true" method="post">' \
         '<input type="hidden" name="message[content]" id="trix_input_1" />' \
-        '<trix-editor id="message_content" input="trix_input_1" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/:signed_id/:filename">' \
+        '<trix-editor id="message_content" input="trix_input_1" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/redirect/:signed_id/:filename">' \
         "</trix-editor>" \
       "</form>",
       output_buffer
@@ -89,7 +89,7 @@ def form_with(*, **)
     assert_dom_equal \
       '<form action="/messages" accept-charset="UTF-8" data-remote="true" method="post">' \
         '<input type="hidden" name="message[content]" id="message_content_trix_input_message" />' \
-        '<trix-editor placeholder="Content" id="message_content" input="message_content_trix_input_message" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/:signed_id/:filename">' \
+        '<trix-editor placeholder="Content" id="message_content" input="message_content_trix_input_message" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/redirect/:signed_id/:filename">' \
         "</trix-editor>" \
       "</form>",
       output_buffer
@@ -105,7 +105,7 @@ def form_with(*, **)
     assert_dom_equal \
       '<form action="/messages" accept-charset="UTF-8" data-remote="true" method="post">' \
         '<input type="hidden" name="message[title]" id="message_title_trix_input_message" />' \
-        '<trix-editor placeholder="Story title" id="message_title" input="message_title_trix_input_message" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/:signed_id/:filename">' \
+        '<trix-editor placeholder="Story title" id="message_title" input="message_title_trix_input_message" class="trix-content" data-direct-upload-url="http://test.host/rails/active_storage/direct_uploads" data-blob-url-template="http://test.host/rails/active_storage/blobs/redirect/:signed_id/:filename">' \
         "</trix-editor>" \
       "</form>",
       output_buffer

activestorage/CHANGELOG.md

@@ -1,3 +1,31 @@
+*   Files can now be served by proxying them from the underlying storage service
+    instead of redirecting to a signed service URL. Use the
+    `rails_storage_proxy_path` and `_url` helpers to proxy an attached file:
+
+    ```erb
+    <%= image_tag rails_storage_proxy_path(@user.avatar) %>
+    ```
+
+    To proxy by default, set `config.active_storage.resolve_model_to_route`:
+
+    ```ruby
+    # Proxy attached files instead.
+    config.active_storage.resolve_model_to_route = :rails_storage_proxy
+    ```
+
+    ```erb
+    <%= image_tag @user.avatar %>
+    ```
+
+    To redirect to a signed service URL when the default file serving strategy
+    is set to proxying, use the `rails_storage_redirect_path` and `_url` helpers:
+
+    ```erb
+    <%= image_tag rails_storage_redirect_path(@user.avatar) %>
+    ```
+
+    *Jonathan Fleckenstein*
+
 *   Add `config.active_storage.web_image_content_types` to allow applications
     to add content types (like `image/webp`) in which variants can be processed,
     instead of letting those images be converted to the fallback PNG format.

activestorage/README.md

@@ -106,6 +106,37 @@ Variation of image attachment:
 <%= image_tag user.avatar.variant(resize_to_limit: [100, 100]) %>
 ```
 
+## File serving strategies
+
+Active Storage supports two ways to serve files: redirecting and proxying.
+
+### Redirecting
+
+Active Storage generates stable application URLs for files which, when accessed, redirect to signed, short-lived service URLs. This relieves application servers of the burden of serving file data. It is the default file serving strategy.
+
+When the application is configured to proxy files by default, use the `rails_storage_redirect_path` and `_url` route helpers to redirect instead:
+
+```erb
+<%= image_tag rails_storage_redirect_path(@user.avatar) %>
+```
+
+### Proxying
+
+Optionally, files can be proxied instead. This means that your application servers will download file data from the storage service in response to requests. This can be useful for serving files from a CDN.
+
+Explicitly proxy attachments using the `rails_storage_proxy_path` and `_url` route helpers:
+
+```erb
+<%= image_tag rails_storage_proxy_path(@user.avatar) %>
+```
+
+Or configure Active Storage to use proxying by default:
+
+```ruby
+# config/initializers/active_storage.rb
+Rails.application.config.active_storage.resolve_model_to_route = :rails_storage_proxy
+```
+
 ## Direct uploads
 
 Active Storage, with its included JavaScript library, supports uploading directly from the client to the cloud.

activestorage/app/controllers/active_storage/base_controller.rb

@@ -5,4 +5,13 @@ class ActiveStorage::BaseController < ActionController::Base
   include ActiveStorage::SetCurrent
 
   protect_from_forgery with: :exception
+
+  private
+    def stream(blob)
+      blob.download do |chunk|
+        response.stream.write chunk
+      end
+    ensure
+      response.stream.close
+    end
 end

activestorage/app/controllers/active_storage/blobs/proxy_controller.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# Proxy files through application. This avoids having a redirect and makes files easier to cache.
+class ActiveStorage::Blobs::ProxyController < ActiveStorage::BaseController
+  include ActiveStorage::SetBlob
+  include ActiveStorage::SetHeaders
+
+  def show
+    http_cache_forever public: true do
+      set_content_headers_from @blob
+      stream @blob
+    end
+  end
+end

activestorage/app/controllers/active_storage/blobs_controller.rb → activestorage/app/controllers/active_storage/blobs/redirect_controller.rb

@@ -4,7 +4,7 @@
 # Note: These URLs are publicly accessible. If you need to enforce access protection beyond the
 # security-through-obscurity factor of the signed blob references, you'll need to implement your own
 # authenticated redirection controller.
-class ActiveStorage::BlobsController < ActiveStorage::BaseController
+class ActiveStorage::Blobs::RedirectController < ActiveStorage::BaseController
   include ActiveStorage::SetBlob
 
   def show

activestorage/app/controllers/active_storage/representations/proxy_controller.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+# Proxy files through application. This avoids having a redirect and makes files easier to cache.
+class ActiveStorage::Representations::ProxyController < ActiveStorage::BaseController
+  include ActiveStorage::SetBlob
+  include ActiveStorage::SetHeaders
+
+  def show
+    http_cache_forever public: true do
+      set_content_headers_from representation.image
+      stream representation
+    end
+  end
+
+  private
+    def representation
+      @representation ||= @blob.representation(params[:variation_key]).processed
+    end
+end

activestorage/app/controllers/active_storage/representations_controller.rb → activestorage/app/controllers/active_storage/representations/redirect_controller.rb

@@ -4,7 +4,7 @@
 # Note: These URLs are publicly accessible. If you need to enforce access protection beyond the
 # security-through-obscurity factor of the signed blob and variation reference, you'll need to implement your own
 # authenticated redirection controller.
-class ActiveStorage::RepresentationsController < ActiveStorage::BaseController
+class ActiveStorage::Representations::RedirectController < ActiveStorage::BaseController
   include ActiveStorage::SetBlob
 
   def show

activestorage/app/controllers/concerns/active_storage/set_headers.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module ActiveStorage::SetHeaders #:nodoc:
+  extend ActiveSupport::Concern
+
+  private
+    def set_content_headers_from(blob)
+      response.headers["Content-Type"] = blob.content_type
+      response.headers["Content-Disposition"] = ActionDispatch::Http::ContentDisposition.format \
+        disposition: params[:disposition] || "inline", filename: blob.filename.sanitized
+    end
+end

activestorage/app/models/active_storage/preview.rb

@@ -69,6 +69,23 @@ def url(**options)
   alias_method :service_url, :url
   deprecate service_url: :url
 
+  # Returns a combination key of the blob and the variation that together identifies a specific variant.
+  def key
+    if processed?
+      variant.key
+    else
+      raise UnprocessedError
+    end
+  end
+
+  def download(&block)
+    if processed?
+      variant.download(&block)
+    else
+      raise UnprocessedError
+    end
+  end
+
   private
     def processed?
       image.attached?

activestorage/app/models/active_storage/variant.rb

@@ -55,6 +55,7 @@
 class ActiveStorage::Variant
   attr_reader :blob, :variation
   delegate :service, to: :blob
+  delegate :content_type, :filename, to: :specification
 
   def initialize(blob, variation_or_variation_key)
     @blob, @variation = blob, ActiveStorage::Variation.wrap(variation_or_variation_key)
@@ -83,6 +84,12 @@ def url(expires_in: ActiveStorage.service_urls_expire_in, disposition: :inline)
   alias_method :service_url, :url
   deprecate service_url: :url
 
+  # Downloads the file associated with this variant. If no block is given, the entire file is read into memory and returned.
+  # That'll use a lot of RAM for very large files. If a block is given, then the download is streamed and yielded in chunks.
+  def download(&block)
+    service.download key, &block
+  end
+
   # Returns the receiving variant. Allows ActiveStorage::Variant and ActiveStorage::Preview instances to be used interchangeably.
   def image
     self

activestorage/app/models/active_storage/variant_with_record.rb

@@ -24,9 +24,7 @@ def image
     record&.image
   end
 
-  def url(**options)
-    image&.url(**options)
-  end
+  delegate :key, :url, :download, to: :image, allow_nil: true
 
   alias_method :service_url, :url
   deprecate service_url: :url

activestorage/config/routes.rb

@@ -2,9 +2,11 @@
 
 Rails.application.routes.draw do
   scope ActiveStorage.routes_prefix do
-    get "/blobs/:signed_id/*filename" => "active_storage/blobs#show", as: :rails_service_blob
+    get "/blobs/redirect/:signed_id/*filename" => "active_storage/blobs/redirect#show", as: :rails_service_blob
+    get "/blobs/proxy/:signed_id/*filename" => "active_storage/blobs/proxy#show", as: :rails_service_blob_proxy
 
-    get "/representations/:signed_blob_id/:variation_key/*filename" => "active_storage/representations#show", as: :rails_blob_representation
+    get "/representations/redirect/:signed_blob_id/:variation_key/*filename" => "active_storage/representations/redirect#show", as: :rails_blob_representation
+    get "/representations/proxy/:signed_blob_id/:variation_key/*filename" => "active_storage/representations/proxy#show", as: :rails_blob_representation_proxy
 
     get  "/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_service
     put  "/disk/:encoded_token" => "active_storage/disk#update", as: :update_rails_disk_service
@@ -19,15 +21,60 @@
     route_for(:rails_blob_representation, signed_blob_id, variation_key, filename, options)
   end
 
-  resolve("ActiveStorage::Variant") { |variant, options| route_for(:rails_representation, variant, options) }
-  resolve("ActiveStorage::VariantWithRecord") { |variant, options| route_for(:rails_representation, variant, options) }
-  resolve("ActiveStorage::Preview") { |preview, options| route_for(:rails_representation, preview, options) }
-
+  resolve("ActiveStorage::Variant") { |variant, options| route_for(ActiveStorage.resolve_model_to_route, variant, options) }
+  resolve("ActiveStorage::VariantWithRecord") { |variant, options| route_for(ActiveStorage.resolve_model_to_route, variant, options) }
+  resolve("ActiveStorage::Preview") { |preview, options| route_for(ActiveStorage.resolve_model_to_route, preview, options) }
 
   direct :rails_blob do |blob, options|
     route_for(:rails_service_blob, blob.signed_id, blob.filename, options)
   end
 
-  resolve("ActiveStorage::Blob")       { |blob, options| route_for(:rails_blob, blob, options) }
-  resolve("ActiveStorage::Attachment") { |attachment, options| route_for(:rails_blob, attachment.blob, options) }
+  resolve("ActiveStorage::Blob")       { |blob, options| route_for(ActiveStorage.resolve_model_to_route, blob, options) }
+  resolve("ActiveStorage::Attachment") { |attachment, options| route_for(ActiveStorage.resolve_model_to_route, attachment.blob, options) }
+
+  direct :rails_storage_proxy do |model, options|
+    if model.respond_to?(:signed_id)
+      route_for(
+        :rails_service_blob_proxy,
+        model.signed_id,
+        model.filename,
+        options
+      )
+    else
+      signed_blob_id = model.blob.signed_id
+      variation_key  = model.variation.key
+      filename       = model.blob.filename
+
+      route_for(
+        :rails_blob_representation_proxy,
+        signed_blob_id,
+        variation_key,
+        filename,
+        options
+      )
+    end
+  end
+
+  direct :rails_storage_redirect do |model, options|
+    if model.respond_to?(:signed_id)
+      route_for(
+        :rails_service_blob,
+        model.signed_id,
+        model.filename,
+        options
+      )
+    else
+      signed_blob_id = model.blob.signed_id
+      variation_key  = model.variation.key
+      filename       = model.blob.filename
+
+      route_for(
+        :rails_blob_representation,
+        signed_blob_id,
+        variation_key,
+        filename,
+        options
+      )
+    end
+  end
 end if ActiveStorage.draw_routes

activestorage/lib/active_storage.rb

@@ -62,6 +62,7 @@ module ActiveStorage
 
   mattr_accessor :routes_prefix, default: "/rails/active_storage"
   mattr_accessor :draw_routes, default: true
+  mattr_accessor :resolve_model_to_route, default: :rails_storage_redirect
 
   mattr_accessor :replace_on_assign_to_many, default: false
   mattr_accessor :track_variants, default: false

activestorage/lib/active_storage/engine.rb

@@ -84,6 +84,7 @@ class Engine < Rails::Engine # :nodoc:
         ActiveStorage.paths             = app.config.active_storage.paths || {}
         ActiveStorage.routes_prefix     = app.config.active_storage.routes_prefix || "/rails/active_storage"
         ActiveStorage.draw_routes       = app.config.active_storage.draw_routes != false
+        ActiveStorage.resolve_model_to_route = app.config.active_storage.resolve_model_to_route || :rails_storage_redirect
 
         ActiveStorage.variable_content_types = app.config.active_storage.variable_content_types || []
         ActiveStorage.web_image_content_types = app.config.active_storage.web_image_content_types || []

activestorage/test/controllers/blobs/proxy_controller_test.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require "test_helper"
+require "database/setup"
+
+class ActiveStorage::Blobs::ProxyControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    @blob = create_file_blob filename: "racecar.jpg"
+  end
+
+  test "invalid signed ID" do
+    get rails_service_blob_proxy_url("invalid", "racecar.jpg")
+    assert_response :not_found
+  end
+
+  test "HTTP caching" do
+     get rails_storage_proxy_url(@blob)
+     assert_response :success
+     assert_equal "max-age=3155695200, public", response.headers["Cache-Control"]
+   end
+end