ssh-error when using Ansible with AWS EC2 - ssh

Question

The scenario is:
AWS Ec2 instances have two users, namely root and ubuntu. root is not
advisable, but AWS recommends using ubuntu as the default
user and this user has all sudo permissions.
Ansible's controlling machine runs on an EC2 instance. The Ansible playbook bootstraps another EC2 instance and installs certain softwares on them.
Node.js web app triggers this Ansible scripts from root user.
The setup works well when all the files for Ansible and Node.js are kept in the same folder. But when organised in different folder, gives Ansible ssh-error.
Error:
So, when organised in separate folders. The nodejs app triggers the ansible scripts. The new Ec2 instance is bootstrapped, but when the SSH-port is ready, cannot install the required softwares as it gives the ssh permission denied error.
The nodejs code that triggers the ansible scripts is executed as
child.exec("ansible playbook ../playbook.yml");
The only change in the code, after organising into folders is the addition of "../" path.
Debugging:
As I told you, there are two users in EC2 instance, the ec2-key module while bootstrapping stores the root's ssh-key to the newly bootstrapped instance. But, while installing the software on the newly bootstrapped instance, ubuntu's ssh=key is used for getting access. Thus, the conflicts with the keys give the ssh-permission denied error. And, this error particularly occurs after organising the Ansible files and Node.js files into separate folders. If all the Ansible and Node.js files are put inn the same folder, then no error is raised. FYI: All files are stored in the ubuntu user.
Just puzzled about this!

Answer 1

As said by #udondan, adding cwd to exec function works.