Cloud-init config example for using the none data source provider to setup a box for usage with vagrant on finding no cloud metadata service.

cloud.cfg

disable_ec2_metadata: True
datasource_list: [ "ConfigDrive", "None"]
datasource:
  None:
    userdata_raw: |
      #!/bin/bash
      groupadd vagrant
      useradd -d /home/vagrant -s /bin/bash -m -g vagrant -G wheel vagrant

      echo "root:vagrant" | chpasswd
      echo "vagrant:vagrant" | chpasswd

      echo "vagrant        ALL=(ALL)       NOPASSWD: ALL" >> /etc/sudoers.d/vagrant
      chmod 0440 /etc/sudoers.d/vagrant

      # set a default HOME_DIR environment variable if not set
      HOME_DIR="${HOME_DIR:-/home/vagrant}";
      mkdir -p $HOME_DIR/.ssh
      echo "ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA6NF8iallvQVp22WDkTkyrtvp9eWW6A8YVr+kz4TjGYe7gHzIw+niNltGEFHzD8+v1I2YJ6oXevct1YeS0o9HZyN1Q9qgCgzUFtdOKLv6IedplqoPkcmF0aYet2PkEDo3MlTBckFXPITAMzF8dJSIFo9D8HfdOV0IAdx4O7PtixWKn5y2hMNG0zQPyUecp4pzC6kivAIhyfHilFR61RGL+GPXQ2MWZWFYbAGjyiYJnAmCP3NOTd0jMZEnDkbUvxhMmBYSdETk1rRgm+R4LOzFUGaHqHDLKLX+FIPKcF96hrucXzcWyLbIbEgE98OHlnVYCzRdK8jlqm8tehUc9c9WhQ== vagrant insecure public key" > $HOME_DIR/.ssh/authorized_keys

      chown -R vagrant $HOME_DIR/.ssh;
      chmod -R go-rwsx $HOME_DIR/.ssh;
    metadata:
       instance-id: vagrant
       local-hostname: vagrant.localdomain

Many of the optiions can be set declaratively, without involving shell scripting: https://cloudinit.readthedocs.io/en/latest/topics/examples.html