Make object store with pages work

The S3 contents is downloaded to a tempfile, which is deleted by Ruby's
GC and closed/unlinked too in an ensure block. The tempfile is extracted
and placed in its usual place.

app/services/projects/update_pages_service.rb

@@ -24,6 +24,7 @@ module Projects
       # Create temporary directory in which we will extract the artifacts
       FileUtils.mkdir_p(tmp_path)
       Dir.mktmpdir(nil, tmp_path) do |archive_path|
+        puts 'starting extraction'
         extract_archive!(archive_path)
         # Check if we did extract public directory
@@ -156,17 +157,17 @@ module Projects
     # This is done using a tempfile as artifacts will be GC'ed
     def extractable_artifacts
       if Gitlab.config.artifacts.object_store.enabled
-        artifacts
-      else
         temp_file.path
+      else
+        artifacts
       end
     end
     def temp_file
       @temp_file ||=
         begin
-          file = Tempfile.new("pages-artifacts-#{job.id}")
-          File.open(file, 'wb') { file.write(job.artifacts_file.read) }
+          file = Tempfile.new(["#{job.id}-pages-artifacts", File.extname(artifacts)])
+          IO.binwrite(file, job.artifacts_file.read)
           file
         end

config/gitlab.yml.example

@@ -136,9 +136,15 @@ production: &base
   ## Build Artifacts
   artifacts:
     enabled: true
-    object_store: false
     # The location where build artifacts are stored (default: shared/artifacts).
     # path: shared/artifacts
+    object_store:
+      enabled: false
+      provider: AWS # Only AWS supported at the moment
+      access_key_id: VXKLW2P7WP83RM3OQAYU
+      secret_access_key: hEm7WuxW3Qct9tsxNqSw+iyP26fcCacz78vErkiI
+      bucket: docker
+      region: eu-central-1
   ## Git LFS
   lfs: