gitlab Backup get Bundler::GemfileNotFound

I try to backup gitlab（11.4.0）
using

docker-compose run --rm gitlab app:rake gitlab:backup:create

from the README.md
and get Error GRPC::Unavailable: 14:Connect Failed that is same as #1744

Then I try to sovle it using the solution in #1655

/sbin/entrypoint.sh app:rake gitlab:backup:create

then I get the Error

Running raketask gitlab:backup:create...
Could not locate Gemfile or .bundle/ directory
Bundler::GemfileNotFound: Could not locate Gemfile or .bundle/ directory
/var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler.rb:223:in `rescue in root'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler.rb:219:in `root'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler.rb:80:in `bundle_path'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/shared_helpers.rb:230:in `validate_bundle_path'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/shared_helpers.rb:312:in `set_path'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/shared_helpers.rb:90:in `set_bundle_environment'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/cli/exec.rb:25:in `run'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/cli.rb:424:in `exec'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/vendor/thor/lib/thor/invocation.rb:126:in `invoke_command'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/vendor/thor/lib/thor.rb:387:in `dispatch'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/cli.rb:27:in `dispatch'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/vendor/thor/lib/thor/base.rb:466:in `start'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/cli.rb:18:in `start'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/exe/bundle:30:in `block in <top (required)>'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/lib/bundler/friendly_errors.rb:124:in `with_friendly_errors'
  /var/lib/gems/2.4.0/gems/bundler-1.16.6/exe/bundle:22:in `<top (required)>'
  /usr/local/bin/bundle:23:in `load'
  /usr/local/bin/bundle:23:in `<main>'

lt looks like not installing bundler or some service did not start

I have do some search but can't sovle it

Start with the README.md backup command and compare it with the /sbin/entrypoint.sh invocation shown in the report. Reproduce the GitLab 11.4.0 backup failure, inspect the entrypoint's working directory and Gemfile availability, and confirm that the documented backup command completes without the GRPC or Bundler::GemfileNotFound errors.