EnvironmentVariablesConfigurationSource replaces _ with .

[Brock Bouchard]

EnvironmentVariablesConfigurationSource replaces _ in the environment variable name with .:

cfg4j/cfg4j-core/src/main/java/org/cfg4j/source/system/EnvironmentVariablesConfigurationSource.java

Lines 73 to 83 in 6998251

   /** 
    * Convert the Environment Variable Name to the expected Properties Key formatting 
    * 
    * @param environmentVariableKey The Env Variable Name, possibly prefixed with the {@link Environment} which 
    *                               in this context serves as a way to namespace variables 
    * @param environmentContext     The Environment context in format: ENVIRONMENTNAME_ 
    * @return A {@link String} with the environment prefix removed and all underscores converted to periods 
    */ 
   private static String convertToPropertiesKey(String environmentVariableKey, String environmentContext) { 
     return environmentVariableKey.substring(environmentContext.length()).replace(ENV_DELIMITER, PROPERTIES_DELIMITER); 
   } 

Unless I missed something, this behavior was not documented at: http://www.javadoc.io/doc/org.cfg4j/cfg4j-core/4.4.0

Thoughts:

a) Why do this in the first place?
b) If the property name is going to be mangled, perhaps also converting to lowercase would be more "expected" per typical Java system property standards?

Thanks,

Brock

[kant]

+1

[Jeff Baker]

I think that replacing _ with . is the right thing to do, as it respects the conventions of using _ as a word separator in environment variable names and links that nicely with the existing convention in properties files of using . to express hierarchy. I also agree that converting to lower case would be the right thing to do, and wrote https://github.com/ExpediaDotCom/haystack-pipes/blob/master/commons/src/main/java/com/expedia/www/haystack/pipes/commons/ChangeEnvVarsToLowerCaseConfigurationSource.java. I'm not totally happy with this implementation...it feels like it ought to leverage the Environment class in cfg4j, but that was problematic because trying to do so insisted on file hierarchy existing which isn't a requirement for environment variable based configuration...but the class works for our use case.

[Mark Holton]

Darn, this tripped me up too. Would be nice if in addition to replacing _ in ENV var with . in property, it also lowercased the property name.

So unless your file-based foo.properties has the same casing as the ENV-based (which for most people is UPPERCASE_WITH_UNDERSCORE), when you try and merge, you get 2 sets of properties instead of ENV overwriting file. This forces you to have uppercased properties in foo.properties which is not ideal/conventional.