#179 Support multiple var-files

[rkettelerij]

Fixes #179

[jrasell]

thanks @rkettelerij for this, I will take a look when I can :)

[jrasell]

@rkettelerij do you know what the load order will be when two configs are parsed so I can write in the README about variable file priorities etc?

[rkettelerij]

@jrasell the variable files are evaluated in the order in which they are specified on the command line. If a particular variable is defined in more than one variable file, the last value specified is effective. E.g:

1.yaml

foo: 1

2.yaml

foo: 2

myjob.nomad

job "[[.foo]]" {
}

./levant render -var-file=1.yaml -var-file=2.yaml myjob.nomad

Will print:

job "2" {
}

Because 2.yaml is specified as the second -var-file and overwrite the value set by -var-file=1.yaml

This is identical to the way Terraform handles multiple var-files.