add config validate

[maxadamo]

Affected Puppet, Ruby, OS and module versions/distributions

• Puppet: n/a
• Ruby: n/a
• Distribution: n/a
• Module version:

How to reproduce (e.g Puppet code you use)

a wrong configuration leads to a service outage.

What are you seeing

certain errors can be detected using nomad config validate against the configuration file.
That doesn't work for everything. If the directory defined in host_volume does not exist, Nomad fails to restart and if puppet runs on all the agent, you'll face an outage.

What behaviour did you expect instead

Let puppet fail if the configuration has issues

Output log

n/a

Any additional information you'd like to impart

I have something in the works and I'll prepare a PR soon.

It's a ruby script which runs nomad config validate and check if the host_volumes have a corresponding file/directory.
Further checks can be easily added to this file.

[maxadamo]

an issue has been open for Nomad: hashicorp/nomad#16968
Meantime the user can choose between the ruby script and nomad validation.