CI Job Trace's inaccessible when using OpenStack Swift

I set up a single-node instance of OpenStack Swift, and I configured our test instance of GitLab CE (11.0) to use it. I have verified that artifact files are being stored correctly within Swift. When I attempt to view the log of a job that has been migrated to object storage, or one that has been run since object storage was enabled, I get a 500 and the following in production.log:

Started GET "/ethan.reesor/alpine/-/jobs/10/trace.json?state=" for 172.24.129.100 at 2018-07-09 10:44:37 -0700
Processing by Projects::JobsController#show as JSON
Parameters: {"namespace_id"=>"ethan.reesor", "project_id"=>"alpine", "id"=>"10"}
Processing by Projects::JobsController#trace as JSON
Parameters: {"state"=>"", "namespace_id"=>"ethan.reesor", "project_id"=>"alpine", "id"=>"10"}
Completed 500 Internal Server Error in 14ms (ActiveRecord: 2.6ms)

Gitlab::Ci::Trace::HttpIO::InvalidURLError (Gitlab::Ci::Trace::HttpIO::InvalidURLError):
lib/gitlab/ci/trace/http_io.rb:20:in 'initialize'
app/uploaders/job_artifact_uploader.rb:23:in 'new'
app/uploaders/job_artifact_uploader.rb:23:in 'open'
app/models/ci/job_artifact.rb:20:in 'open'
lib/gitlab/ci/trace.rb:67:in 'block in read'
lib/gitlab/ci/trace/stream.rb:18:in 'initialize'
lib/gitlab/ci/trace.rb:65:in 'new'
lib/gitlab/ci/trace.rb:65:in 'read'
app/controllers/projects/jobs_controller.rb:67:in 'trace'
lib/gitlab/i18n.rb:50:in 'with_locale'
lib/gitlab/i18n.rb:56:in 'with_user_locale'
app/controllers/application_controller.rb:362:in 'set_locale'
lib/gitlab/middleware/multipart.rb:95:in 'call'
lib/gitlab/request_profiler/middleware.rb:14:in 'call'
lib/gitlab/middleware/go.rb:17:in 'call'
lib/gitlab/etag_caching/middleware.rb:11:in 'call'
lib/gitlab/middleware/read_only/controller.rb:28:in 'call'
lib/gitlab/middleware/read_only.rb:16:in 'call'
lib/gitlab/request_context.rb:18:in 'call'
lib/gitlab/metrics/requests_rack_middleware.rb:27:in 'call'
lib/gitlab/middleware/release_env.rb:10:in 'call'

My config:

gitlab_rails['artifacts_enabled'] = true
# gitlab_rails['artifacts_path'] = "/mnt/storage/artifacts"
gitlab_rails['artifacts_object_store_enabled'] = true
gitlab_rails['artifacts_object_store_remote_directory'] = "artifacts"
gitlab_rails['artifacts_object_store_connection'] = {
  'provider' => 'openstack',
  'openstack_auth_url' => 'http://my-object01.example.com:35357/v3/auth/tokens',
  'openstack_username' => 'gitlab',
  'openstack_api_key' => '****',
  'openstack_project_name' => 'gitlab',
  'openstack_domain_id' => 'default'
}