how can I use ansible to push playbooks with SSH keys authentification - ansible

Question

I am new to ansible and try to push playbooks to my nodes. I would like to push via ssh-keys. Here is my playbook:
- name: nginx install and start services
hosts: <ip>
vars:
ansible_ssh_private_key_file: "/path/to/.ssh/id_ed25519"
become: true
tasks:
- name: install nginx
yum:
name: nginx
state: latest
- name: start service nginx
service:
name: nginx
state: started
Here is my inventory:
<ip> ansible_ssh_private_key_file=/path/to/.ssh/id_ed25519
before I push, I check if it works: ansible-playbook -i /home/myuser/.ansible/hosts nginx.yaml --check
it gives me:
fatal: [ip]: UNREACHABLE! => {"changed": false, "msg": "Failed to connect to the host via ssh: user#ip: Permission denied (publickey,password).", "unreachable": true}
On that server I don't have root privileges, I cant do sudo. That's why I use my own inventory in my home directory. To the target node where I want to push that nginx playbook, I can do a SSH connection and perform a login. The public key is on the remote server in /home/user/.ssh/id_ed25119.pub
What am i missing?

Answer 1

Copy /etc/ansible/ansible.cfg into the directory from which you are running the nginx.yaml playbook, or somewhere else per the documentation: https://docs.ansible.com/ansible/latest/reference_appendices/config.html#ansible-configuration-settings-locations
Then edit that file to change this line:
#private_key_file = /path/to/file
to read:
private_key_file = /path/to/.ssh/id_ed25519
Also check the remote user_user entry.