Core Nextflow: auto assign profiles

[ewels]

Originally posted on the Nextflow repo: nextflow-io/nextflow#792 but was auto-closed due to inactivity. I still think it's a cool idea, so reposting here.

Suggestion is to make a PR to Nextflow to add functionality to config profiles, to allow them to be automatically assigned when a certain condition is met. That logic could be anything, but my initial suggestion was to match the system hostname.

In short, the aim is to make Nextflow support the following syntax:

profiles {
  uppmax {
    when = host.hostname.contains('.uppmax.uu.se')
    includeConfig 'conf/uppmax.config'
  }
  system_two {
    when = host.hostname.contains('.system_two.com')
    includeConfig 'conf/system_two.config'
  }
  system_three {
    when = System.getEnv('SOME_VAR') == 'myvalue'
    includeConfig 'conf/system_two.config'
  }
}

Paolo gave some advice back on the original thread. The most pertinent bit is probably the following:

The config object is parsed using the ConfigParser. The first goal is to understand how the when definition is mapped in the config object. The ConfigParserTest can help to make some experiments.

Then once we have the auto profile information it should be enforce in the ConfigBuilder at this point.