Load configuration values from optional files or resources

[aneveux]

Hello!

Thanks a lot for all the good work you put in that library, it looks really nice! I tested it on simple use cases and everything is going really fine for me, but I have one use case I'd like to use it for, and I can't manage to find a solution yet.

I had a look at the documentation, the source code, and all past issues, but couldn't manage to find an answer, which is why I created this issue.

My concern is pretty simple, right now I'm writting this:

val configuration = Config { addSpec(ServerSpec) }
    .from.yaml.resource("production.yml")
    .from.yaml.resource("local.yml")
    .from.yaml.watchFile("./debug.yml")
    .from.env()
    .from.systemProperties()

Because what I'd like to have is:

• load the configuration from the production.yml resource (which will always be there, and packaged for production)
• if I'm on my development environment, I'll have a local.yml file as a resource as well, but it is ignored by Git, so it won't be packaged. I'd like to load it when it is present, but it'll obviously won't be there on production,
• while on production, if a file called debug.yml is present at the path I specified, I'd like to load it and use its values, otherwise, I'd like it to be ignored.

Right now my issue is that if something isn't present, I have exceptions such as: java.io.FileNotFoundException: config.yml (No such file or directory). Which is normal since the file doesn't exist, but I'd like the framework just to ignore that source silently.

From my point of view, I could either write something like:

val configuration = Config { addSpec(ServerSpec) }
    .disable(Feature.FAIL_ON_UNFOUND_SOURCE)
    .from.yaml.resource("production.yml")
    .from.yaml.resource("local.yml")
    .from.yaml.watchFile("./debug.yml")
    .from.env()
    .from.systemProperties()

or something like:

val configuration = Config { addSpec(ServerSpec) }
    .from.optional.yaml.resource("production.yml")
    .from.optional.yaml.resource("local.yml")
    .from.optional.yaml.watchFile("./debug.yml")
    .from.env()
    .from.systemProperties()

Of course if there are any other solutions (existing or not) you have in mind, do not hesitate to let me know.

What do you think about this use case? If I can be of any help regarding the resolution of that issue, do not hesitate to tell me.

Thanks a lot for your attention and your help! Have a great day!

[aneveux]

Just for information, I tested the #34 pull request over my actual example, and it does the job :)

Don't hesitate to let me know how you'd like (if you'd like) to solve such issue :)

Have a great day!

[lfmunoz]

I have the same exact issue I want to load a file only if it exists, if it doesn't exist don't do anything.

[lfmunoz]

Workaround

  val configDefault = Config { addSpec(ServerSpec) }
    .from.yaml.resource("default.yml")

  val configLoad =
   try {
     Config { addSpec(ServerSpec) }
       .from.yaml.file("config.yml")
       .from.env() // SERVER_HOST=0.0.0.0
       .from.systemProperties()  // -Dserver.host=0.0.0.0 -Dserver.port=8080
   } catch (e : FileNotFoundException) {
      Config{ addSpec(ServerSpec) }
   }

  val finalConfig =  configDefault + configLoad 

[uchuhimo]

@aneveux @lfmunoz I release a new version v0.14.0 that contains the required feature. Now file/URL/resource/Git sources have a new argument optional to indicate whether they are optional or not. optional is false by default, but you can use config.enable(Feature.OPTIONAL_SOURCE_BY_DEFAULT) to make optional=true by default for all default loaders. You can give them a try.

[aneveux]

Thank you very much @uchuhimo! I'll give it a try tomorrow :)

Thanks for your time and your attention! Have a great day!