How to setup MySQL with cloud-init?

How can I do this?

From what I’ve been able to understand, I can’t setup MySQL without a root account. Is this true?

Here’s my cloud-init configuration:

#cloud-config

users:
    - name: dev
    ssh-authorized-keys:
        - ssh-rsa AB3NzaC1yc...
    sudo: ['ALL=(ALL) NOPASSWD:ALL']
    groups: sudo
    shell: /bin/bash

packages:
    - mysql-client
    - libmysqlclient-dev
    - mysql-server

package-update: true
package_upgrade: true

runcmd:

#
# SSH
#
    - sed -i -e '/^Port/s/^.*$/Port 22/' /etc/ssh/sshd_config
    - sed -i -e '/^PermitRootLogin/s/^.*$/PermitRootLogin no/' /etc/ssh/sshd_config
    - sed -i -e '/^PasswordAuthentication/s/^.*$/PasswordAuthentication no/' /etc/ssh/sshd_config
    - sed -i -e '$aAllowUsers dev' /etc/ssh/sshd_config

    - sudo service ssh restart

#
# Firewall
#

    # defaults
    - sudo ufw default deny incoming
    - sudo ufw default allow outgoing

    # exceptions
    - sudo ufw allow ssh
    - sudo ufw allow http
    - sudo ufw allow https

    # start on boot
    - sed -i -e '/^ENABLED/s/^.*$/ENABLED=yes/' /etc/ufw/ufw.conf

    - sudo ufw enable

Nothing very fancy,

With this config, root login is disabled and I get remote access with my dev user account. So far, so good.

However, MySQL installations fails with:

Errors were encountered while processing:
 /var/cache/apt/archives/mysql-server-5.7_5.7.17-0ubuntu0.16.04.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
Cloud-init v. 0.7.8 running 'modules:final' at Sun, 29 Jan 2017 12:09:56 +0000. Up 14.23 seconds.
2017-01-29 12:11:24,114 - util.py[WARNING]: Failed to install packages: ['mysql-client', 'libmysqlclient-dev', 'mysql-server']
2017-01-29 12:11:24,125 - cc_package_update_upgrade_install.py[WARNING]: 1 failed with exceptions, re-raising the last one
2017-01-29 12:11:24,128 - util.py[WARNING]: Running module package-update-upgrade-install (<module 'cloudinit.config.cc_package_update_upgrade_install' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_package_update_upgrade_install.py'>) failed

If I don’t specify any user, and perform a typical setup through apt-get the installation runs fine.

Is it not possible to setup MySQL with cloud-init while having my root account disabled? And if not, can I somehow tell cloud-init to setup my users after my packages have been installed/updated?

Thank you!