Composer Parameter file

Composer uses a JSON file to persist user-defined parameters value.

Synthax

This is the syntax for a JSON file:

{
  "repoName": {
    "parameterName": "@type String, @desc Defines the value for this specific parameter."
  }  
}

An example:

{
    "repo1": {
        "branch": "96a2e5889b9baef42163eb950f3d87032bf62891 refs/pull/4/head",
        "simpleParamWithDefault": "myDefault"
    }
}

How it works

Parameter's name and value are available for REPO hooks (look here). It allows a user to influence the core behaviour of an REPO. Hence, an INV Groovy file.
In fact, you could pass a parameter's value through Composer, to the REPO Hook (let's say init), write a temporary file, then read it from your INV Groovy script file. A more complete example: myRepo.json:

{
  "my-repo": {
    "myParameters": "value"  
  }
}

myRepo.groovy

repo {
    name "my-repo"
    ...
    hooks {
        init """
# Do the actual init (git clone, etc)
echo ${myParameters} > temp
"""
    } 
}

myINV.groovy

inv {
    name "my-inv"
    ...
    broadcast { Something } using {
        ready {
            // $pwd indicates the INV Groovy script location
            // It should correspond to the REPO "path" computed or user-defined value. 
            return new File($pwd, "temo").text
        }   
    }
}

Location

Each JSON files are expected to be located at: ${RepoFileParent}/${RepoFileName}-values.json.
Per example:
For the Repo Groovy script located at /usr/local/etc/inv/repos/MyRepoFile.groovy, the JSON parameters file is expected to be located at /usr/local/etc/inv/repos/MyRepoFile-values.json

Extension ".groovy" is not required for the Groovy script file, but ".json" does for the parameters file.