git error while deploying through chef

问题:

i am trying to deploy rails app through chef code. recipe contains code

deploy_revision "testapp" do    
  repo "REPO_URL"    
  ssh_wrapper "/home/ubuntu/.ssh/chef_ssh_deploy_wrapper.sh"    
  environment({    
    "RAILS_ENV" => "staging"    
  })    
  deploy_to "/home/ubuntu/testapp"    
  branch "master"    
  user "ubuntu"    
  group "ubuntu"    
  scm_provider Chef::Provider::Git    
end   

and sshwrapper file contains

exec ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no github.com -i "/home/ubuntu/.ssh/id_rsa" "$@"     

when i ran bootstrap

im getting error as follows

STDERR: Warning: Permanently added 'github.com,192.30.252.129' (RSA) to the list of known hosts.
192.168.1.32 Permission denied (publickey).
192.168.1.32 fatal: Could not read from remote repository.
192.168.1.32 Please make sure you have the correct access rights
192.168.1.32 and the repository exists.
192.168.1.32 ---- End output of git ls-remote "REPO_URL" master* ----

so , unable to figure it out the reason. Any help would be appreciated.