Hey everyone, does anyone know how to unit test SSE on the client side (Android, iOS), I couldn't find any examples

Hi everybody 👋🏼 I'm looking for opensource BE projects that are using Ktor What's your recommandations ?

Hi everyone, I'm running into a weird issue and I'm wondering if anyone can point in the right direction - we are using Ktor client to talk to a backend built by another team and backend responds with 401 in some cases but I have a feeling it returns a malformed response which results in

io.ktor.utils.io.ClosedByteChannelException

on our client. More details in thread

Hi, I'm using the ktor plugin to do OpenAPI specification generation, but the

operationId

is empty for every route. Does the plugin not have an option to set the

operationId

or what would be the intended way to set it?

With Ktor Sockets, I'm getting

io.ktor.utils.io.ConcurrentIOException: Concurrent read attempts

on Native but not on the JVM, running the same code. Are there platform-specific limitations around this? Am I just lucky on the JVM? It is possible to programmatically detect if this is allowed or not on the current platform?

Related to the above: I have one coroutine writing to the socket, and one reading. Is that allowed? The error mentions "concurrent read attempts", but I don't think I have multiple coroutines reading. The reading coroutine uses

while (currentCoroutineContext().isActive) {
    select {
        // …

        async {
		    readChannel.awaitContent(4 * 4) // standard message header size
		}.onAwait { isActive ->
            // …
        }
    }
}

Maybe that's not the correct way to use a

ByteReadChannel

in a

select

expression?

Hello! I had a question about Status Pages plugin and upcoming Kotlin Rich errors. Will we be able to handle rich errors in a similar way we can do now with exceptions and Status Pages plugin? (See attached screenshot for context, considering that Exceptions will then be replaced by rich errors and be responded with call.respond() for example)

Hello, I noticed that if you throw a bad request exception, the error message isn't returned in the response. Is this intentional?

Hi everyone! The survey is still live, and we’d really appreciate it if you could fill it out and share your feedback so we can continue improving the framework. Thank you!

Hello. I am trying to serve sitemap.xml in the root as https://example.com/sitemap.xml using

routing {
   staticResources("/", "files")
}

When I call directly in the browser it works, but when I do:

curl -I <http://example.com/sitemap.xml>

The response is: HTTP/1.1 404 Not Found Content-Length: 853 Content-Type: text/html; charset=UTF-8 I suppose this content is from the Status Pages plugin:

install(StatusPages) {
   statusFile(HttpStatusCode.NotFound, filePattern = "error#.html")
}

I have tried the same with curl in localhost with same results. Is this normal behaviour?

Hi, is there any course on using Ktor for backend development with token-based authentication? I want to learn how to build a secure backend.

Are there recommended approaches to version an Api? Something like

/api/v1/...

,

/api/v2/...

, but without lot's of duplicate code?

https://youtrack.jetbrains.com/issue/KTOR-9135/buildOpenApi-fails-with-unknown-serializer anyone running in this issue too?

Has anyone here used the ktor html DSL to build a component library, like you would do with React or Vue? Reusable HTML components, represented by classes or functions. I was trying to do so, but with createHTML() I ended up always returning the html of the component as a string, which forces me to wrap it with unsafe{}. I'm sure theres a better solution to this, maybe someone has an idea?

Hi everyone! 👋 I’m curious to know if anyone here is using SSE with Kotlin and the Ktor client. If so, I’d love to hear about your experience—how you use it, how often, and which parts you find repetitive in your day-to-day work. I’m also wondering whether you think it would be useful to auto-generate some of that boilerplate code using tools like Ktorgen or Ktorfit. As far as I know, Retrofit doesn’t support SSE, but if you know of a similar library that does, I’d really appreciate the recommendation! The idea is to gather a bit of “real-world usage data” on how much SSE is used with the Ktor client, and whether generating parts of the setup (like URL configuration or callbacks, which seem to be the most automatable pieces) would actually be helpful for developers. Thanks in advance for sharing your experience! 🙌ktor new

Question regarding Ktor’s DI container - is there a way to scope the dependencies or are they singletons by default only?

Does the android client support happy eyeballs?

can CIO support Http 2.0 under Ktor?

Is there any chance I can write into a stream on a regular HTTP Request? Like a WebSocket, but without the WebSocket-Layer, just the raw Stream. The Docker Engine gives a

Upgrade: tcp

header when starting an exec-Instance without detaching and I want to be. able to write into that stream as stdin. Is it possible to get the ByteWriteChannel of the connection in the .execute { ... }-Block? If not, I could imagine this channel being exposed as a function that requires you to OptIn.

client.socket.preparePost("/exec/$execId/start") {
    contentType(ContentType.Application.Json)
    setBody(StartExecInstanceResponse(detach = false))
}.execute { response ->
    response.rawInput // would return the ByteWriteChannel for this request
}

Another issue that I found with the Ktor Client Java engine, it seems that you are unable to override the

Host

header with the Java engine (while it does work with the CIO engine) https://youtrack.jetbrains.com/issue/KTOR-9158/Cannot-override-the-Host-header-with-the-Java-client-engine

hi, we have got error with apache5 as httpClient and use it as Ktor DI. So when the server restart, we will get this error.

java.nio.channels.CancelledKeyException: null at java.base/sun.nio.ch.SelectionKeyImpl.ensureValid(Unknown Source) at java.base/sun.nio.ch.SelectionKeyImpl.interestOps(Unknown Source) at org.apache.hc.core5.reactor.IOSessionImpl.setEvent(IOSessionImpl.java:172) at org.apache.hc.core5.reactor.IOSessionImpl.enqueue(IOSessionImpl.java:115) at org.apache.hc.core5.reactor.ssl.SSLIOSession.enqueue(SSLIOSession.java:775) at org.apache.hc.core5.reactor.InternalDataChannel.enqueue(InternalDataChannel.java:286) at org.apache.hc.client5.http.impl.async.HttpAsyncClientBuilder.lambda$build$2(HttpAsyncClientBuilder.java:1077) at org.apache.hc.core5.reactor.SingleCoreIOReactor.initiateSessionShutdown(SingleCoreIOReactor.java:155) at org.apache.hc.core5.reactor.SingleCoreIOReactor.doExecute(SingleCoreIOReactor.java:115) at org.apache.hc.core5.reactor.AbstractSingleCoreIOReactor.execute(AbstractSingleCoreIOReactor.java:92) at org.apache.hc.core5.reactor.IOReactorWorker.run(IOReactorWorker.java:44) at java.base/java.lang.Thread.run(Unknown Source)

is it anyway to close the apache5 with Ktor DI?

Would love to contribute! Any ktor maintainer to let me know if I should start working on it? This is a missing feature that would be used by a lot of backends (configurable with 2/3 lines of codes instead of implementing a custom solution) https://youtrack.jetbrains.com/issue/KTOR-9162/Ktor-server-auth-api-key-plugin

hey everyone, is there something like the newly shipped feature in IntelliJ idea that has support for Spring versioning but for Ktor, or an easy/elegant way to handle this in Ktor?

using ktor server - what's the recommended way to make concurrent requests to 3rd party services over http?

routing {
    get("/data") {
        val combinedData = coroutineScope { 
            val dataOneDeferred = async { clientOne.get("data") }
            val dataTwoDeferred = async { clientTwo.get("data") }
        
            return@coroutineScope dataOneDeferred.await() + dataTwoDeferred.await()
        }
        call.respond(combinedData)
    }
}

OTEL tracing issue with Ktor 3 Hey guys, We just upgraded our service from Ktor 2.X.X to Ktor 3.2.3 During testing, we suddenly lost some metrics, specifically: new version loose

http.route

tag and our Grafana dashboards started to go crazy. Anybody else notice some different behavior in metrics when moving to Ktor 3?

It wasn’t the correct channel after all

Hi everyone! We're using WebRTC with Ktor and have noticed some inconsistency when it comes to the IceServer urls specification. The IceServer data class calls the parameter

urls

but it only takes in a singular string. Also the comment above it references MDN that specifies this parameter as "single string or an array of strings". We've been making multiple IceServer objects per URL that we are passing in, but shouldn't this then rather be a list of URLs instead? We're also wondering if there may be an advantage from a browser optimization point of view when passing in a list of URLs for one IceServer. Here's the line in question: https://github.com/ktorio/ktor/blob/6b3bad4b947d0a07c3a9887d2558c9400c3c49ac/ktor-[…]t/ktor-client-webrtc/common/src/io/ktor/client/webrtc/WebRtc.kt

hello guys when using ktor OpenAPI Gradle extension, it does look the request and response body don't support enum type if present, how to go around it

Hi everyone 👋 I’m setting up dev and prod environment configuration in a Ktor application. Is there any recommended article/blog that explains the best practice for handling dev vs prod? Thanks!

I wanted to do basically what this issue mentions here https://youtrack.jetbrains.com/issue/KTOR-8775/Make-Default-Request-builder-suspend, which is to call a suspending function during each request to append a header. I noticed that HttpSend plugin exists https://ktor.io/docs/client-http-send.html which feels like it should work fine for this. I am doing smth like this, is this a fair workaround until something else exists to achieve this?

HttpClient().config
  defaultRequest {
    header(... add non-suspend headers here)
  }
  install(HttpSend)
}.apply {
  plugin(HttpSend).intercept { request ->
    execute(request.apply { header(... add suspend headers here) })
  }
}