kotlinlang #ktor

Sorry for what's likely a dumb question, but I haven't been able to grok it from searching around: if I have an existing jetty server and want to add a ktor app as a javax servlet, how do I do that? I see lots of docs talking about deploying to jetty, but I'm confused how it actually works. I see reference to filling out reference.conf, but I don't follow how that would work. I also found

JettyApplicationEngine

, but didn't find much on how to use it.

Grantas33

04/30/2020, 1:06 PM

Is it possible to specify multiple types to return from a httpClient's request depending whether the request succeeded (status code 200+) or failed (status code 300-500+)?. This is with JsonFeature configured and the server returning application/json content type.

Ivan Brko

04/30/2020, 4:42 PM

Hi all, I am using ktor with kotlinx.serialization (for a server application), and I am not much familiar with neither one of those. I have a data class that has a field of type LocalDateTime, it doesn't have a default serializer so I wrote it, but is there a way I could register a serializer in ktor for a class so that I don't always have to write the following when some data class has a property of that type?

@Serializable(with = LocalDateTimeSerializer::class)

Henry

04/30/2020, 5:32 PM

Not sure if this is allowed but would appreciate some feedback on a fun little problem I was working on https://henrycourse.com/2020/04/30/async-caching-in-ktor-with-a-minor-detour/

maxmello

04/30/2020, 6:12 PM

I installed the Timeout feature of the Ktor HttpClient, because I have some specific request that might take a long time, so I installed the feature:

httpClient = HttpClient(CIO) {
        install(HttpTimeout) {
            requestTimeoutMillis = 60000
        }
        engine {
            maxConnectionsCount = 10000 
            endpoint.apply {
                maxConnectionsPerRoute = 1000 
                pipelineMaxSize = 100
                keepAliveTime = 5000 
                connectTimeout = 5000 
                connectRetryAttempts = 3
            }
        }
}

and in my request, I specifically overwrite the requestTimeout:

<http://httpClient.post|httpClient.post><MyResponse> {
                    url(myUrl)
                    contentType(ContentType.Application.Json)
                    timeout {
                        requestTimeoutMillis = TimeUnit.MINUTES.toMillis(30)
                    }
                    body = myBody
}

But I still got a coroutine

TimeoutCancellationException

after 15 seconds. I then specified the engine.endpoint.requestTimeout to be longer and the Exception went away - so am I not able to overwrite the CIO engines timeout with the Timeout feature? By the Timeout feature documentation, a

HttpRequestTimeoutException

should be thrown, not a Coroutine timeout exception, so it appears to get ignored. Can I overwrite the request timeout for CIO for a specific request? Or should I increase the CIO timeout a lot and then use the HttpTimeout feature to reduce it again?

Colton Idle

05/01/2020, 2:58 AM

Caching is super important. I've only worked on mobile (android) and although I understand the basics of http, I'm really just now diving into headers and caching specifically. At the same time I'm learning a bit of backend development with ktor and I really want to nail my caching mechanism. It seems silly to me that so many backend systems don't have caching setup properly. I've read that there are ways to just use timestamps or tokens so that a server doesn't send you the same damn data again. Going off of this though, as a super new "backend" dev does anyone have any seminal talks or blog posts on the subject? Thank you

Imran

05/01/2020, 8:57 AM

any signup/login example of ktor with mongodb ?

John O'Reilly

05/01/2020, 4:46 PM

Is it possible to use Ktor WebSocket client library in Kotlin/Native (as part of KMP project)?

Ivan Brko

05/02/2020, 5:52 AM

Hi all, I am playing with Ktor and I can't get the routes (for custom features I'm implementing) in right order, I would be grateful for any help or links to more informations about how route pipelines are merged. Basically I am using built-in authentication and I want to add my own authorization. This is how I'm testing it in the routing code:

authenticate{
  minimalRoleAllowed(Role.Admin) { //this is the call to my custom feature for authorization
    get{
      ...
    }
  }
}

So what I would expect here to happen is have authentication called, and then if it passes have authorization called. But it seems, somehow, that when all the pipelines are merged authorization gets called before authentication, which is of course wrong, because I can't authorize the user if I they are not authenticated. This is the implementation for my

minimalRouteAllowed

extension method:

fun Route.minimalRoleAllowed(role: Role, build: Route.() -> Unit): Route {
    val authorisedRoute = createChild(AuthorisedRouteSelector()) //AuthorisedRouteSelector just returns a selector which evaluates to RouteSelectorEvaluation.Const

    application.feature(RoleAuthorization).interceptPipeline(authorisedRoute, role)

    authorisedRoute.build()
    return authorisedRoute
}

And this is how I'm inserting phase and intercepting in the

RoleAuthorization.interceptPipeline

called above (the

pipeline

here is

authorizedRoute

I sent in method above):

pipeline.insertPhaseAfter(ApplicationCallPipeline.Features, authorizationPhase)
pipeline.intercept(authorizationPhase) {...

Nikola Milovic

05/02/2020, 10:28 AM

Can Ktor be used as a game server to manage user data, authentication and such?

louiscad

05/02/2020, 1:35 PM

Familiar with OkHttp and retrofit, I tried to give ktor client a try but I'm now giving up for the following reasons: 1. I failed to find how to find out what kind of `Throwable`s an http call can throw (for Retrofit, it's HttpException, IOException, and RuntimeException from custom converters, interceptors or authenticator), which is a big deal as I don't want to show "unknown error" to the user and be clueless as to the call failure root cause. 2. I didn't find how I can set a pipeline "middleware" that can detect some errors (like HTTP 401), do an operation (e.g. attempt to refresh the token), and then retry the call without the initial caller having to retry. I mean, unless I do it using OkHttp authenticator, but that forces me to stick to the OkHttp engine while I wanted to try

CIO

, and going multiplatform. It seems to me that ktor sever doc got a lot more love than ktor client. If that's really the case, is reducing that imbalance planned?

❤️ 2

waltermcq

05/02/2020, 9:28 PM

if JDBC is blocking, what is the benefit of using coroutines for async database calls through exposed w/ postgres?

Jitesh

05/03/2020, 12:26 PM

2020-05-03 17:46:18.630 [main] DEBUG com.zaxxer.hikari.HikariConfig - HikariPool-1 - configuration:
2020-05-03 17:46:18.634 [main] DEBUG com.zaxxer.hikari.HikariConfig - allowPoolSuspension.............false
2020-05-03 17:46:18.635 [main] DEBUG com.zaxxer.hikari.HikariConfig - autoCommit......................false
2020-05-03 17:46:18.635 [main] DEBUG com.zaxxer.hikari.HikariConfig - catalog.........................none
2020-05-03 17:46:18.635 [main] DEBUG com.zaxxer.hikari.HikariConfig - connectionInitSql...............none
2020-05-03 17:46:18.635 [main] DEBUG com.zaxxer.hikari.HikariConfig - connectionTestQuery.............none
2020-05-03 17:46:18.635 [main] DEBUG com.zaxxer.hikari.HikariConfig - connectionTimeout...............30000
2020-05-03 17:46:18.635 [main] DEBUG com.zaxxer.hikari.HikariConfig - dataSource......................none
2020-05-03 17:46:18.635 [main] DEBUG com.zaxxer.hikari.HikariConfig - dataSourceClassName.............none
2020-05-03 17:46:18.635 [main] DEBUG com.zaxxer.hikari.HikariConfig - dataSourceJNDI..................none
2020-05-03 17:46:18.675 [main] DEBUG com.zaxxer.hikari.HikariConfig - dataSourceProperties............{password=<masked>}
2020-05-03 17:46:18.675 [main] DEBUG com.zaxxer.hikari.HikariConfig - driverClassName................."org.postgresql.Driver"
2020-05-03 17:46:18.675 [main] DEBUG com.zaxxer.hikari.HikariConfig - healthCheckProperties...........{}
2020-05-03 17:46:18.675 [main] DEBUG com.zaxxer.hikari.HikariConfig - healthCheckRegistry.............none
2020-05-03 17:46:18.675 [main] DEBUG com.zaxxer.hikari.HikariConfig - idleTimeout.....................600000
2020-05-03 17:46:18.675 [main] DEBUG com.zaxxer.hikari.HikariConfig - initializationFailTimeout.......1
2020-05-03 17:46:18.675 [main] DEBUG com.zaxxer.hikari.HikariConfig - isolateInternalQueries..........false
2020-05-03 17:46:18.676 [main] DEBUG com.zaxxer.hikari.HikariConfig - jdbcUrl.........................jdbc:postgresql:testDB?user=postgres;

2020-05-03 17:46:18.683 [main] INFO  com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Starting...
2020-05-03 17:46:18.736 [main] DEBUG com.zaxxer.hikari.pool.PoolBase - HikariPool-1 - Failed to create/setup connection: FATAL: role "postgres;" does not exist
2020-05-03 17:46:18.737 [main] DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Cannot acquire connection from data source

codec

05/05/2020, 4:42 AM

I also have a question about authentication. When a user logs out, how do we invalidate the UserIdPrincipal and clear out the UserPasswordCredential?

Giovanni Alluvatti

05/05/2020, 9:52 AM

Hello there! I have a question on how to test e2e (making rest calls) a ktor+kodein application. The test should be included in the application project. I can explain better with a comparison to spring boot since I'm migrating from it. In Spring Boot I can create a test annotated with

@SpringBootTest

, starting up my application with a real context (no mocks); then using a

TestRestTemplate

I can call my rest api exposed to

<http://localhost>:{springBootRandomPort}

. Does anybody know a similar smart way to test this scenario also for a ktor + kodein app? Unfortunately I wasn't able to find any examples on official documentation.

melatonina

05/05/2020, 11:49 AM

Hello. I may need to switch back from Kotlin 1.3.72 to 1.3.61. Which version of Ktor should I use with Kotlin 1.3.61? Is it Ktor 1.3.1?

Ivan Brko

05/06/2020, 2:31 PM

Hi all, I am trying to add swagger to a Ktor application and I found https://github.com/nielsfalk/ktor-swagger and it seems nice, but not really active. Do people use this project, as I can see that there are opened PRs from months ago and that version of the lib for Ktor 1.3 hasn't been released yet? Does anyone know if the author has given up on the library or just doesn't have enough time to work on it lately?

Dias

05/06/2020, 3:25 PM

I am asking, because at some point something in my app stops making http calls and it's not obvious where that happens, I am not using coroutines, just

httpClient.get<HttpResponse>(...)

. I doesn't look that httpresponse needs to be closed, but maybe I am leaking resources somewhere?

:thread-please: 1

Henry

05/07/2020, 8:01 AM

basic one but what's the best pattern for accessing config in top level functions (or is this just not the way to do things)? e.g.

fun fetchInternalClientInstance() { ...I need access to application.config in here...}

on a wider point could anyone link me to some resources discussing higher level application architecture with ktor as I'm starting to get beyond what is covered by the Youkube example?

👍 2

Ivan Brko

05/07/2020, 12:51 PM

Asked i serialization channel, nobody replied, maybe someone knows here: Does anyone know if I can somehow register a serializer in ktor (using kotlinx.serialization)? I am writing a Ktor sever and I need to return a data class from a 3rd party library, so I can't annotate it with @Serializable. I can write a serializer for it, but how to tell Ktor to use this serializer?

bitkid

05/07/2020, 3:14 PM

Hi! Is there a specific reason why exceptions thrown in

call.respondOutputStream{ throw BlaException()}

are not recoverable, meaning that they dont get propagated to the status pages handler?

Nikky

05/07/2020, 8:35 PM

how likely is the Locations api (type-safe routing) to be removed ? since the

@KtorExperimentalLocationsAPI

warns about that

Matthieu Stombellini

05/07/2020, 10:55 PM

Hi everyone. I need to test some user routes in an app that I'm building. These endpoint use a (header-based) session. My question is, how can I tell the sessions feature to "create" a session before calling that user endpoint? What I'm doing right now is calling the actual logging-in endpoint to set up the session properly and using the header that that returns.

Nikky

05/08/2020, 10:10 AM

is there any way to use

kotlin.serialization

for the Sessions feature? in particular how the data class is turned into some sort of string.. whni i extend

SessionStorage

to store those strings in postgres, i would like to have json or structured data instead of however it serializes fields

Rodrigo Silva

05/09/2020, 7:26 PM

Can i create my own oauth2 server with ktor?

Kirill Prybylsky

05/10/2020, 2:15 PM

Hello everyone, I am trying to implement websocket feature with ktor, but I only get 404 for the http://localhost:8080/ request in browser. Could you, please, tell me what can be wrong? Here is my websocket implementation:

webSocket("/") {
    while (true) {
        delay(3000)
        outgoing.send(Frame.Text("hi"))
    }
}

Mario Trucco

05/10/2020, 2:57 PM

Hey everyone! I believe that this is a bug:

scheme

returned instead of

version

. Is it ok if I open an issue and link it in a fix PR?

Robin Larsen

05/10/2020, 9:21 PM

Hi! I'm trying to decide whether to go with Firebase for user authentication or with the Ktor features, namely Sessions and Authentication (JWT). However, I haven't been able to find some good guides on Firebase Admin and Ktor integration, which makes it harder to go down that route. But at the same time, I'm and Android developer, so I don't know that much about web, and I'd feel more comfortable delegating the responsibility to Firebase if the implementation is simple. Anyone know whether it's worthwhile/possible to make Ktor work with Firebase? And possibly link some guides?

rudolf.hladik

05/11/2020, 8:36 AM

Hi everyone, is there a snapshot of ktor client which uses native-mt coroutines?

david.bilik

05/12/2020, 6:22 AM

hi, I have a weird problem with dependencies resolution while using

auth

artifact. This is my build.gradle

plugins {
    id 'java'
    id 'org.jetbrains.kotlin.jvm' version '1.3.72'
}

apply plugin: 'java'

repositories {
    jcenter()
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
    def ktor_version = '1.3.0'
    implementation "io.ktor:ktor-client-okhttp:$ktor_version"
    implementation "io.ktor:ktor-client-gson:$ktor_version"
    implementation "io.ktor:ktor-client-auth:$ktor_version"
    implementation "io.ktor:ktor-client-logging:$ktor_version"
}

compileKotlin {
    kotlinOptions.jvmTarget = "1.8"
}

and I am trying to use Basic authentication when making a request from the client but

import io.ktor.client.features.auth.Auth

is not resolved in the IDEA even though I can see it in external libraries in the project structure. I thought that it can be related with gradle version, but I’ve updated to 6.1.1 and nothing changed

Title

david.bilik

05/12/2020, 6:22 AM

hi, I have a weird problem with dependencies resolution while using

auth

artifact. This is my build.gradle

plugins {
    id 'java'
    id 'org.jetbrains.kotlin.jvm' version '1.3.72'
}

apply plugin: 'java'

repositories {
    jcenter()
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
    def ktor_version = '1.3.0'
    implementation "io.ktor:ktor-client-okhttp:$ktor_version"
    implementation "io.ktor:ktor-client-gson:$ktor_version"
    implementation "io.ktor:ktor-client-auth:$ktor_version"
    implementation "io.ktor:ktor-client-logging:$ktor_version"
}

compileKotlin {
    kotlinOptions.jvmTarget = "1.8"
}

and I am trying to use Basic authentication when making a request from the client but

import io.ktor.client.features.auth.Auth

Looks like using artifact

"io.ktor:ktor-client-auth-jvm:$ktor_version"

helps but is it necessary?

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