Fix project import from remote to import from S3

Currently, `Import::GitlabProjects::CreateProjectFromRemoteFileService`
validates:
1. The file size based on the `Content-Length` header, which S3 doesn't
   returb on `head` requests;
1. The file content type, which S3 use `application/x-tar` instead of
   `application/gzip` for a `tar.gz`;

Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/337230

Changelog: fixed
MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/75170

app/services/import/gitlab_projects/create_project_from_remote_file_service.rb

@@ -4,7 +4,10 @@ module Import
   module GitlabProjects
     class CreateProjectFromRemoteFileService < CreateProjectFromUploadedFileService
       FILE_SIZE_LIMIT = 10.gigabytes
-      ALLOWED_CONTENT_TYPES = ['application/gzip'].freeze
+      ALLOWED_CONTENT_TYPES = [
+        'application/gzip',   # most common content-type when fetching a tar.gz
+        'application/x-tar'   # aws-s3 uses x-tar for tar.gz files
+      ].freeze
 
       validate :valid_remote_import_url?
       validate :validate_file_size
@@ -44,17 +47,27 @@ module Import
       end
 
       def validate_content_type
+        # AWS-S3 presigned URLs don't respond to HTTP HEAD requests,
+        # so file type cannot be validated
+        # https://gitlab.com/gitlab-org/gitlab/-/merge_requests/75170#note_748059103
+        return if amazon_s3?
+
         if headers['content-type'].blank?
           errors.add(:base, "Missing 'ContentType' header")
         elsif !ALLOWED_CONTENT_TYPES.include?(headers['content-type'])
           errors.add(:base, "Remote file content type '%{content_type}' not allowed. (Allowed content types: %{allowed})" % {
             content_type: headers['content-type'],
-            allowed: ALLOWED_CONTENT_TYPES.join(',')
+            allowed: ALLOWED_CONTENT_TYPES.join(', ')
           })
         end
       end
 
       def validate_file_size
+        # AWS-S3 presigned URLs don't respond to HTTP HEAD requests,
+        # so file size cannot be validated
+        # https://gitlab.com/gitlab-org/gitlab/-/merge_requests/75170#note_748059103
+        return if amazon_s3?
+
         if headers['content-length'].to_i == 0
           errors.add(:base, "Missing 'ContentLength' header")
         elsif headers['content-length'].to_i > FILE_SIZE_LIMIT
@@ -64,6 +77,10 @@ module Import
         end
       end
 
+      def amazon_s3?
+        headers['Server'] == 'AmazonS3' && headers['x-amz-request-id'].present?
+      end
+
       def headers
         return {} if params[:remote_import_url].blank? || !valid_remote_import_url?
 

spec/services/import/gitlab_projects/create_project_from_remote_file_service_spec.rb

@@ -18,9 +18,10 @@ RSpec.describe ::Import::GitlabProjects::CreateProjectFromRemoteFileService do
 
   subject { described_class.new(user, params) }
 
+  shared_examples 'successfully import' do |content_type|
     it 'creates a project and returns a successful response' do
       stub_headers_for(remote_url, {
-      'content-type' => 'application/gzip',
+        'content-type' => content_type,
         'content-length' => '10'
       })
 
@@ -35,6 +36,10 @@ RSpec.describe ::Import::GitlabProjects::CreateProjectFromRemoteFileService do
       expect(response.payload.path).to eq('path')
       expect(response.payload.namespace).to eq(user.namespace)
     end
+  end
+
+  it_behaves_like 'successfully import', 'application/gzip'
+  it_behaves_like 'successfully import', 'application/x-tar'
 
   context 'when the file url is invalid' do
     it 'returns an erred response with the reason of the failure' do
@@ -79,7 +84,7 @@ RSpec.describe ::Import::GitlabProjects::CreateProjectFromRemoteFileService do
       expect(response).not_to be_success
       expect(response.http_status).to eq(:bad_request)
       expect(response.message)
-        .to eq("Remote file content type 'application/js' not allowed. (Allowed content types: application/gzip)")
+        .to eq("Remote file content type 'application/js' not allowed. (Allowed content types: application/gzip, application/x-tar)")
     end
   end
 
@@ -130,6 +135,20 @@ RSpec.describe ::Import::GitlabProjects::CreateProjectFromRemoteFileService do
     end
   end
 
+  it 'does not validate content-type or content-length when the file is stored in AWS-S3' do
+    stub_headers_for(remote_url, {
+      'Server' => 'AmazonS3',
+      'x-amz-request-id' => 'Something'
+    })
+
+    response = nil
+    expect { response = subject.execute }
+      .to change(Project, :count)
+
+    expect(response).to be_success
+    expect(response.http_status).to eq(:ok)
+  end
+
   context 'when required parameters are not provided' do
     let(:params) { {} }