SecretAuthenticationProvider for Ktor 1.6.x

SecretAuthenticationProvider.kt

import io.ktor.application.*
import io.ktor.auth.*
import io.ktor.request.*

class SecretAuthenticationProvider internal constructor(config: Configuration) : AuthenticationProvider(config) {

    internal val key: (ApplicationCall) -> String? = config.key
    internal val expectedKey: String? = config.expectedKey

    class Configuration internal constructor(name: String?) : AuthenticationProvider.Configuration(name) {

        internal var key: (ApplicationCall) -> String? = { call -> call.request.header("secret") }

        internal var expectedKey: String? = null

        internal fun build() = SecretAuthenticationProvider(this)
    }
}

fun Authentication.Configuration.secret(
    name: String? = null,
    configure: SecretAuthenticationProvider.Configuration.() -> Unit
) {
    val provider = SecretAuthenticationProvider.Configuration(name).apply(configure).build()
    provider.pipeline.intercept(AuthenticationPipeline.RequestAuthentication) {
        val expectedKey = provider.expectedKey ?: throw Exception("No key provided")
        if (expectedKey != provider.key(call)) {
            throw AuthenticationException()
        }
    }
    register(provider)
}