Cloud-init config to allow password-less sudo via ssh-agent

user_data.yml

#cloud-config

## I want to authenticate sudo via ssh-agent on Ubuntu 22.04

users:
  - name: bob
    gecos: Bob
    shell: /bin/bash
    primary_group: bob
    groups: sudo
    ssh_authorized_keys:
      - ssh-ed25519 AAsomekeyhere

write_files:
  - path: /etc/pam.d/common-local-auth-ssh
    content: |
      # initial value only - deploy keys to /etc/ssh/users/ and remove next line
      auth sufficient pam_ssh_agent_auth.so file=~/.ssh/authorized_keys
      auth sufficient pam_ssh_agent_auth.so file=/etc/ssh/users/%u
  - path: /etc/sudoers.d/0ssh-agent-auth
    content: |
      Defaults env_keep += "SSH_AUTH_SOCK"
    permissions: '0440'

packages:
  - libpam-ssh-agent-auth
  
runcmd:
  - sed -i '8i @include common-local-auth-ssh' /etc/pam.d/sudo