Best practices solution

1. No modules are used, a direct reference to resources can be found in do.tf.
2. A versions.tf is missing, who knows if this code works with the current versions.
3. No CI has been configured.
4. The README.md suggests to use terraform.tfvars for sensitive variables.
5. Nothing is variable, variables.tf is missing.
6. No output is shown on apply. (outputs.tf)

Bonus: (In the three branch) An ssh-key in a public repository is never a good idea.