Fix 404s with snippet uploads in object storage

Previously, an HTTP request for
`/uploads/-/system/personal_snippet/:snippet_id/:hash/:filename` would
look for an uploader of `PersonalFileUploader` class and use
`PersonalFileUploader#upload_paths` to search the datbase for one of the
following paths:

1. `:hash/:filename`
2. `uploads/-/system/personal_snippet/:id/:hash/:filename`

However, when the upload were stored in object storage,
`PersonalFileUploader#store_dirs` stored the path as:

`personal_snippet/:snippet_id/:hash`

The extraneous `uploads/-/system` prefix prevented the path from being
matched, and uploads in object storage would return a 404 error. Uploads
in local storage would work fine.

To fix this, we set the `#base_dir` properly so that `#upload_paths`
generates the right value for object storage. Note that this also makes
`#store_dirs` do the right thing in `FileUploader`.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/52595

app/uploaders/personal_file_uploader.rb

@@ -6,8 +6,15 @@ class PersonalFileUploader < FileUploader
     options.storage_path
   end
 
-  def self.base_dir(model, _store = nil)
-    File.join(options.base_dir, model_path_segment(model))
+  def self.base_dir(model, store = nil)
+    base_dirs(model)[store || Store::LOCAL]
+  end
+
+  def self.base_dirs(model)
+    {
+      Store::LOCAL => File.join(options.base_dir, model_path_segment(model)),
+      Store::REMOTE => model_path_segment(model)
+    }
   end
 
   def self.model_path_segment(model)
@@ -33,13 +40,6 @@ class PersonalFileUploader < FileUploader
     store_dirs[object_store]
   end
 
-  def store_dirs
-    {
-      Store::LOCAL => File.join(base_dir, dynamic_segment),
-      Store::REMOTE => File.join(self.class.model_path_segment(model), dynamic_segment)
-    }
-  end
-
   private
 
   def secure_url

changelogs/unreleased/sh-fix-snippet-uploads-path-lookup.yml

+---
+title: Fix 404s with snippet uploads in object storage
+merge_request: 24550
+author:
+type: fixed

spec/uploaders/personal_file_uploader_spec.rb

@@ -4,19 +4,13 @@ describe PersonalFileUploader do
   let(:model) { create(:personal_snippet) }
   let(:uploader) { described_class.new(model) }
   let(:upload) { create(:upload, :personal_snippet_upload) }
-  let(:identifier) { %r{\h+/\S+} }
 
   subject { uploader }
 
-  it_behaves_like 'builds correct paths' do
-    let(:patterns) do
-      {
-        store_dir: %r[uploads/-/system/personal_snippet/\d+],
-        upload_path: identifier,
-        absolute_path: %r[#{CarrierWave.root}/uploads/-/system/personal_snippet/\d+/#{identifier}]
-      }
-    end
-  end
+  it_behaves_like 'builds correct paths',
+                  store_dir: %r[uploads/-/system/personal_snippet/\d+],
+                  upload_path: %r[\h+/\S+],
+                  absolute_path: %r[#{CarrierWave.root}/uploads/-/system/personal_snippet\/\d+\/\h+\/\S+$]
 
   context "object_store is REMOTE" do
     before do
@@ -25,13 +19,17 @@ describe PersonalFileUploader do
 
     include_context 'with storage', described_class::Store::REMOTE
 
-    it_behaves_like 'builds correct paths' do
-      let(:patterns) do
-        {
-          store_dir: %r[\d+/\h+],
-          upload_path: identifier
-        }
-      end
+    it_behaves_like 'builds correct paths',
+                    store_dir: %r[\d+/\h+],
+                    upload_path: %r[^personal_snippet\/\d+\/\h+\/<filename>]
+  end
+
+  describe '#upload_paths' do
+    it 'builds correct paths for both local and remote storage' do
+      paths = uploader.upload_paths('test.jpg')
+
+      expect(paths.first).to match(%r[\h+\/test.jpg])
+      expect(paths.second).to match(%r[^personal_snippet\/\d+\/\h+\/test.jpg])
     end
   end