Hello :wave: What is the proper way to create Ktor server plugin that also auto-configures routes? i...

# ktor

[Dariusz Kuc]

Hello 👋
What is the proper way to create Ktor server plugin that also auto-configures routes? i.e. https://ktor.io/docs/custom-plugins-base-api.html#create mentions BaseApplicationPlugin that accepts a pipeline (e.g. ApplicationCallPipeline) and BaseRouteScopedPlugin which should be applied to a specific route.

Should I just use Application which extends ApplicationCallPipeline?

[Aleksei Tirman [JB]]

Do you need to add some routes or write a plugin which can be applied to a route?

[ribesg]

I just use a Routing.setupMyPlugin(…) function as entry point for this kind of libraries

[ribesg]

Even if there was a way, your plugin could be installed before the Routing plugin, how could you add a route then?

[Dariusz Kuc]

👋 I'm new to ktor hence asking. I just started looking into our feature request -> https://github.com/ExpediaGroup/graphql-kotlin/issues/1471

TLDR expectation is plugin would accept user configuration (ie which queries are supported) to create GraphQL server accepting requests on some specified routes (ie /graphql)

[Dariusz Kuc]

Ktor docs (and examples) talk about some very basic stuff like adding a header or logging requests. Was wondering what is the recommendation for application level plugins that process incoming requests

[Dariusz Kuc]

ie asking all folks to implement the same routes in their apps seems like a bad experience

[ribesg]

Can't you do something like Application.pluginOrNull(Routing) and add routes like that? I don't remember if a plugin can access the app but I think it can?

[Dariusz Kuc]

Thats why I'm asking :)

[Dariusz Kuc]

Application extends ApplicationCallPipeline

[Dariusz Kuc]

So I can access the app in configure function

[ribesg]

val MyTestPlugin = createApplicationPlugin("MyTestPlugin") {
        
        application.plugin(Routing).run { 
            
            get("/") { call.respond("Hello world") }
            
        }
        
    }

[ribesg]

You would add some error handling when Routing isn't setup before your plugin but it should just work

[Dariusz Kuc]

👍 sounds good

[ribesg]

application.pluginOrNull(Routing) ?: error("MyTestPlugin requires Routing plugin to be setup before") or something

[Dariusz Kuc]

btw ktor already exposes this (which I'm going to use) ->

public fun Application.routing(configuration: Routing.() -> Unit): Routing =
    pluginOrNull(Routing)?.apply(configuration) ?: install(Routing, configuration)

[ribesg]

What if the user installs your plugin then installs Routing using install(Routing) afterwards?

[Dariusz Kuc]

user error I guess