service configuration using environment variables

[gskorupa]

If the value of a service parameter starts with the sign "$" then that value will be taken from the environment variable.

For example servicetitle parameter value will be taken from STITLE environment variable:

{
    "@type": "org.cricketmsf.config.ConfigSet",
    "services": [
        {
            "@type": "org.cricketmsf.config.Configuration",
            "id": "MyService",
            "service": "com.my.Service",
            "properties": {
                "servicetitle": "$STITLE",
                ...
            },
            "ports": [
             .... 
           ]
     }
}

In case of configuration of adapters, support for this mechanism can be implemented in the adapter's loadProperties method:
E.g.:

public void loadProperties(HashMap<String, String> properties, String adapterName) {
        super.loadProperties(properties, adapterName);
        token = properties.getOrDefault("token", "");
        if (token.startsWith("$")) {
            token = System.getenv(token.substring(1));
        }
}