When I add the `io.ktor:ktor-server-config-yaml-jv...

# kvision

[Mark Fisher]

When I add the io.ktor:ktor-server-config-yaml-jvm dependency to a project, and build the jar task, the default io.ktor.server.config.HoconConfigLoader is not being added to the list of ConfigLoaders in META-INF/services/io.ktor.server.config.ConfigLoader

This has the knock on effect that the "application.conf" file in the root of the jar is not able to be loaded, as there is no ConfigLoader class available to handle that file type.

See thread. I've reproduced this in the examples application.

[Mark Fisher]

I've tracked it down to the fact the class is missing from the ConfigLoader in the jar file.

Do you know how I can force that in when building the kvision fat jar?
This file in the jar:

META-INF/services/io.ktor.server.config.ConfigLoader

is missing this entry when you include the YAML config loader in the dependencies:

io.ktor.server.config.HoconConfigLoader

[Mark Fisher]

I've found that in the addressbook fullstack ktor application, the file does contain the Hocon loader (as it's the default), however, if I add this dependency to the project:

implementation("io.ktor:ktor-server-config-yaml-jvm:$ktorVersion")

Then it swaps to only the Yaml config loader:

io.ktor.server.config.yaml.YamlConfigLoader

It seems that the default Hocon config is not listed if the Yaml one is included when building the jar file, but is when loading via IDE / jvmRun.

I think this should work, if you start the application via the "jvmRun" task (i.e. non JAR), then both ConfigLoader classes are loaded, but not through just running the jar file.

[Robert Jaros]

I can't really help you because I'm not even the author of the shadowJar task code. It was contributed very long time ago and it is still used:
https://github.com/rjaros/kvision/blob/master/kvision-tools/kvision-gradle-plugin/src/main/kotlin/io/kvision/gradle/KVisionPlugin.kt#L305-L314

[Robert Jaros]

The task just takes the list of files from jvmRuntimeClasspath configuration, but I have no idea what it really means 🙂

[Robert Jaros]

It is possible it somehow conflicts with Ktor runtime configuration, but I don't know how to fix this.

[Mark Fisher]

Thanks! It's not a major concern, certainly not for me, as it's a small project and I can use either yaml or hocon. It's only an issue for anyone wanting to use both for some reason.

I did ask this in #C0A974TJ9 too
(link here)

I've some history with writing gradle plugins myself. I might have a look if there are any obvious bits in ktor's plugins that provide their own fatJar task that does something here. The kvision plugin doesn't seem to target the config loader specifically from a brief look, so may require deeper investigation.