Is it possible to override response headers? I’m requesting a resource that is a JSON file, but it is in the text file and response

Content-Type

header is

application/octet-stream

. That is why when I’m requesting this resource, I’m getting

No transformation found

exception, because Json serializer doesn’t know it should parse this file. When I tell serializer to handle also this content type it works properly:

install(JsonFeature) {
    serializer = serializerProvider.get()
    accept(ContentType.Application.Json, ContentType.Application.OctetStream)
}

but it fell a little bit hacky to do it for all requests Is there a better solution? (of course the best it would be to fix it on the API side, but I don’t have an access to it)

Hello! How do I set a

TrustManager

in a ktor client?

When I run my Ktor app, I get this message in the log:

ERROR ktor.application - Unhandled: GET - /favicon.ico
java.lang.NumberFormatException: For input string: "favicon.ico"

Why is this happening? I never make a GET request for that file.

I've opened my project in IDEA 2020.3.2, and this error appeared in

install(ContentNegotiation) { gson { this.setPrettyPrinting() } }

:

Cannot access class 'com.google.gson.GsonBuilder'. Check your module classpath for missing or conflicting dependencies

Why is this happening? I have

ktor-gson

included as a gradle dependency.

hi, sorry if this has been asked before but using the ktor HttpClient and trying to receive an

HttpResponse

from a

<http://client.post|client.post><HttpResponse>(url) {}

it does not seem to throw any exceptions on 4xx or 5xx response codes. Is this the intended behavior? It doesn’t mention on the docs that the default response validator doesn’t fire in this scenario. If the type is switched from

HttpResponse

to

String

it throws the error

Why does ktor create a new dispatcher on okhttp? https://github.com/ktorio/ktor/blob/d7d1b65796a1b05f40a0d1d652b3c3f4e26351b2/ktor-client/ktor-client-okhttp/jvm/src/io/ktor/client/engine/okhttp/OkHttpEngine.kt#L146 Quoting jesse:

For most efficiency, you'll have one ConnectionPool​ and one Dispatcher in your process. These can be shared by many OkHttpClient instances.

https://github.com/square/okhttp/issues/3372#issuecomment-304830644

Hi. Any chance i can get help on the question?

Anyone have an example of making a

HEAD

request with Ktor's

HttpClient

specifically with using CIO engine? This request:

httpClient.head<HttpResponse> {
    url {
         protocol = URLProtocol.HTTPS
         host = "<http://www.website.com/trying/to/get/etag/outta/here|www.website.com/trying/to/get/etag/outta/here>"
    }
}

Returns

java.nio.channels.UnresolvedAddressException

only when using CIO engine. When using another engine, e.g. Android, its completes fine. Wondering if there's something special I need to be doing with CIO head requests.

This is happening only when I let ktor serialize my data. If I invoke

json.encodeToString()

explicitly, the serialization work as expected. I'm using ktor 1.5.1. Why is this happening?

use new project - ktor guide create new ktor project .

Hi all! I have made an ktor microservice application. Basically I can run the app in a monolithic mode, or build every sourceset into a separate fat jar. I now locally run the 11 postgreql databases and 24 ktor microservices with docker compose. The microservices communicate with each other through an NGINX reverse proxy (also from outside you'd go through this same proxy). I was wondering: is there a nice dashboard I can use to see the usage of the pods (or of the reverse proxy)?

Hey all. Does Ktor have first class support for Flow API? Instead of using suspend for the HttpClient request GET function could we have it support Flow types?

I'm trying to make G Cloud App Engine work with my Ktor project, but when I stop the

appengineRun

task and re-launch, I get

Caused by: <http://java.net|java.net>.BindException: Address already in use: bind

, and when I refresh

localhost:8080

, it still works, even though the task is stopped. What is going on?

Hi! Using ktor 1.5.2. I'm getting these Netty exceptions in the logs:

java.lang.IllegalArgumentException: text is empty (possibly HTTP/0.9)
at io.netty.handler.codec.http.HttpVersion.valueOf(HttpVersion.java:64)
at io.netty.handler.codec.http.HttpRequestDecoder.createMessage(HttpRequestDecoder.java:95)
at io.netty.handler.codec.http.HttpObjectDecoder.decode(HttpObjectDecoder.java:250)
...
2021-03-01 12:39:12.067 [eventLoopGroupProxy-4-31] TRACE Application - Failed to decode request
java.lang.IllegalArgumentException: invalid version format: D|¢Þ:À/ÀÀ'À0ÀÀ(/<5=AÀ+À À#À,À
at io.netty.handler.codec.http.HttpVersion.<init>(HttpVersion.java:120)
...
INFO Application - >>> REQUEST: Unhandled: GET - /templates <- I added these logs for debugging

The requests are made using Chrome (so it's not HTTP/0.9 for sure). It seems even I get the exceptions the requests are received. Any ideas?

Has anyone tried running ktor on graalvm in the last year, and able to share their experiences?

hello is there also support for HATEOAS ON KTOR? we run at the moment the spring kotlin stack. I want try something new:)

Is there any particular set of reasons for requiring “wildcard imports” in Ktor? I am pretty sure ie. exposed requires “no wildcard imports” and seems the google guide for java is the same.

When trying to use the Ktor Logging plugin on a multiplatform client where do the logs show? I dont see any log messages in the logcat in Android Studio, I want to see my http requests for debugging. I have it setup just as shown in the docs

private val _client: HttpClient = HttpClient(engine) {
    install(JsonFeature) {
        val json = kotlinx.serialization.json.Json {
            this.isLenient = true
            this.ignoreUnknownKeys = true
        }
        serializer = KotlinxSerializer(json)
    }
    install(Logging) {
        logger = Logger.DEFAULT
        level = LogLevel.ALL
    }
}

I have auto-reload enabled and class changes lead to “Changes in application detected” and reloading of my ktor module, however the module is NOT actually reloaded. I use adopt-openjdk-15 on mac os and run ktor from within intellij idea as an kotlin application. the module callback is an top level extension function. any idea what possibly goes wrong?

I'm trying to build a simple ktor client that I can use in my JS code. But the client is coroutine heavy, and @JsExport doesn't work with coroutines. Is there a way to do this?

In ktor 1.3 there were plans to add multi platform support to ktor server after the release of 1.4 What happened to these plans? Have they been postponed our abandoned?

Hi, I noticed that

call.receive<Data>()

throws a

JsonDecodingException

instead of a

ContentTransformationException

if the data passed with the request doesnt match the data type i try to receive. Is this normal? What I want to do is use

StatusPage

to handle errors in my route handlers.

is ktor auto-reload dependent on a specific version of the jdk in order to work?

Hi all! I have a question about reified function calls from abstract classes:

abstract class BaseClient<T> constructor(private val httpClient: HttpClient) {

    suspend fun get(): T = httpClient.get<T>("/api/") // T is a reified type: HttpClient.get<reified T>(path: String)

}

Rightly, it will not work and Intellij gives me a warning: Use a class instead! I have the issue, that I cannot pass a class as the httpclient doesn't support that (at least out of the box) Is there any way I can make this work? Or add some kind of 1 line code I should add/override in the child class that extends from BaseClient?

@Marcelo you can see at https://ktor.io/docs/jwt.html

We can’t use regexes in ktor server CORS feature yet?

Upgrading from 1.4.3 to 1.5.2 causes trouble with Netty Hello all, this is my first post to this Slack. I use Ktor to build the backend of a platform where podcasts can get sponsorships through host-read ads. While trying to upgrade Ktor from 1.4.3 to 1.5.2, I ran in some trouble with Netty. As I am still quite a newbie to the whole Kotlin/Ktor ecosystem, I have no clue what's going wrong. I use a HOCON File for configuration. I am lost. Any hint where I can start to look for a reason is welcome! Can someone please have a look at the stracktrace below?

Responding at <http://0.0.0.0:9090>
Failed to initialize a channel. Closing: [id: 0xce532d4b, L:/[0:0:0:0:0:0:0:1]:9090 - R:/[0:0:0:0:0:0:0:1]:62473]
java.lang.NoSuchMethodError: 'kotlinx.coroutines.channels.Channel kotlinx.coroutines.channels.ChannelKt.Channel$default(int, kotlinx.coroutines.channels.BufferOverflow, kotlin.jvm.functions.Function1, int, java.lang.Object)'
	at io.ktor.server.netty.cio.NettyRequestQueue.<init>(NettyRequestQueue.kt:19)
	at io.ktor.server.netty.NettyChannelInitializer.configurePipeline(NettyChannelInitializer.kt:104)
	at io.ktor.server.netty.NettyChannelInitializer.initChannel(NettyChannelInitializer.kt:89)
	at io.ktor.server.netty.NettyChannelInitializer.initChannel(NettyChannelInitializer.kt:28)
	at io.netty.channel.ChannelInitializer.initChannel(ChannelInitializer.java:129)
	at io.netty.channel.ChannelInitializer.handlerAdded(ChannelInitializer.java:112)
	at io.netty.channel.AbstractChannelHandlerContext.callHandlerAdded(AbstractChannelHandlerContext.java:938)
	at io.netty.channel.DefaultChannelPipeline.callHandlerAdded0(DefaultChannelPipeline.java:609)
	at io.netty.channel.DefaultChannelPipeline.access$100(DefaultChannelPipeline.java:46)
	at io.netty.channel.DefaultChannelPipeline$PendingHandlerAddedTask.execute(DefaultChannelPipeline.java:1463)
	at io.netty.channel.DefaultChannelPipeline.callHandlerAddedForAllHandlers(DefaultChannelPipeline.java:1115)
	at io.netty.channel.DefaultChannelPipeline.invokeHandlerAddedIfNeeded(DefaultChannelPipeline.java:650)
	at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:502)
	at io.netty.channel.AbstractChannel$AbstractUnsafe.access$200(AbstractChannel.java:417)
	at io.netty.channel.AbstractChannel$AbstractUnsafe$1.run(AbstractChannel.java:474)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.ktor.server.netty.EventLoopGroupProxy$Companion$create$factory$1$1.run(NettyApplicationEngine.kt:227)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Thread.java:832)

Check out this episode of Keeping Up With the Kardashians on Hulu! https://www.hulu.com/watch/82f3db3a-b821-49c0-a87a-f3c100bdd874?utm_source=shared_link

Didn't know that the Kardashians use Ktor

Upgrading from 1.4.3 to 1.5.2 introduces routing precedence? Hello again, when I upgraded from 1.4.3 to 1.5.2, all of my routes serving GET requests yielded a 404 on accessing them. To me it seems, that in 1.5.2 the order of registering routes has become significant, while in 1.4.3 it didn't matter. In the example below, context "/groot" yields a 404. If staticResources() is called after groot(), route "/groot" becomes available as expected. Is this behaviour by design? If so, what are the rules by which routes take precedence over each other? Can someone please look into this? Regards, Bertram

class SomeApp {
    fun Application.main(testing: Boolean = false) {
        
        install(ContentNegotiation) {
            gson {
                setPrettyPrinting()
            }
        }  

        routing {
            underpants()       // serves context "/underpants"
            staticResources()  // serves root context "/"
            groot()            // serves context "/groot"
        }
    }
}

// Route for static context
fun Routing.staticResources() {
    // Serves frontend resources embedded in application jar
    static("/") {
        defaultResource("index.html", "web-resource")
        resources("web-resource")
    }
}

fun Routing.underpants(
) {
    route("/underpants") {
        get {
            val map: HashMap<Int, String> = hashMapOf(1 to "Collect underpants.", 2 to "?", 3 to "Profit!")
            call.respond(map)
        }
    }
}

fun Routing.groot(
) {
    route("/groot") {
        get {
            val map: HashMap<Int, String> = hashMapOf(1 to "I", 2 to "am", 3 to "Groot!")
            call.respond(map)
        }
    }
}