Getting SSH error when run the deploy script

[yoongyy]

PLAY [Deploy matic mainnet full node] ************************************************************************************************************************************

TASK [Gathering Facts] ***************************************************************************************************************************************************
fatal: [localhost]: UNREACHABLE! => {"changed": false, "msg": "Failed to connect to the host via ssh: Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts.\r\nubuntu@localhost: Permission denied (publickey).", "unreachable": true}

PLAY RECAP ***************************************************************************************************************************************************************
localhost : ok=0 changed=0 unreachable=1 failed=0 skipped=0 rescued=0 ignored=0

Hi, I am getting above error when try to run 'ansible-playbook -v -i hosts deploy.yml'
I guess is the SSH issue, how do I add the public key to it?