Hi, I am looking at a way to implement an authorisation model within a http4k application. The use case is quite basic, users will have a set of roles, and roles will have a set of permissions. User permissions will then allow/deny users’ access to protected routes. Does anyone know if there is any support in http4k for this kind of use case?

Hey guys, this might be a question with an obvious answer, but I’m currently quite confused 😂 We have an application that fetches data from an external service and authenticates via OAuth2. No user interactions, just service -> external service. I’m currently transferring the Spring implementation to http4k and just realized how much I have forgotten about OAuth 🌚 Long story short: I guess for the given use case I have to follow this guide?

hi all, when uploading a file through a multipart form, we want to keep the temp file around for async virus scanning. However, in the following piece of code, the file is deleted upon JVM exit:

private fun writeToDisk(part: StreamingPart, bytes: ByteArray, length: Int) =
        File.createTempFile(part.fileName ?: UUID.randomUUID().toString()
        + "-", ".tmp", temporaryFileDirectory).apply {
            deleteOnExit()
            FileOutputStream(this).apply {
                write(bytes, 0, length)
                use { part.inputStream.copyTo(it, writeToDiskThreshold) }
            }
        }

with the

deleteOnExit()

call. We want to keep the file around even when the JVM exits (we're running on k8s so pods can always be killed). Would it be a good idea to make this behaviour configurable, i.e. through a flag that is passed from

MultipartFormBody.from

to the

MultipartFormParser

? If so, I'll make a merge request... Happy to hear your thoughts.

Is anyone seeing constant Undertow server errors in the latest http4k

4.33.1.0

version? It doesn't seem to actually break anything, but the volume of error logs are a problem.

UT005013: An IOException occurred
java.io.IOException: UT000034: Stream is closed
        at io.undertow.channels.DetachableStreamSourceChannel.getOption(DetachableStreamSourceChannel.java:200)
        at io.undertow.io.UndertowInputStream.<init>(UndertowInputStream.java:71)
        at io.undertow.server.HttpServerExchange$DefaultBlockingHttpExchange.getInputStream(HttpServerExchange.java:2001)
        at io.undertow.server.HttpServerExchange.getInputStream(HttpServerExchange.java:1615)
        at org.http4k.server.Http4kUndertowHttpHandler.asRequest(Http4kUndertowHttpHandler.kt:34)
        at org.http4k.server.Http4kUndertowHttpHandler.handleRequest(Http4kUndertowHttpHandler.kt:37)
        at io.undertow.server.Connectors.executeRootHandler(Connectors.java:391)
        at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:859)
        at org.jboss.threads.ContextHandler$1.runWith(ContextHandler.java:18)
        at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2513)
        at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1538)
        at org.xnio.XnioWorker$WorkerThreadFactory$1$1.run(XnioWorker.java:1282)
        at java.base/java.lang.Thread.run(Thread.java:833)

For anyone who's using the GraalVM native image with http4k, we've just pushed a new set of Docker images which support GraalVM 22.3.0 and Java 11, 17 and 19. The Amazon linux-based Serverless on Lambda runtime has also been updated. You can find all the new images on our dockerhub

How am I supposed to create a

Response

with JSON from a string? This seems to work:

Response(Status.OK).header("Content-Type", ContentType.APPLICATION_JSON.value).body("""{"foo":"bar","baz":17}""")

but is there some nicer way?

Is it possible for a server to protect from a malicious client sending humongous requests? And for a client to protect from a malicious server sending humongous responses? I tried to simulate this, and got

java.lang.OutOfMemoryError

when using a lens, since it reads the whole payload into memory before parsing it:

class StreamBody(override val stream: InputStream, override val length: Long? = null) : Body {
    override val payload: ByteBuffer by lazy { stream.use { ByteBuffer.wrap(it.readBytes()) } }
    // ...
}

It would be nice to be able to specify a max payload size.

hi everyone 👋 😀, I’m a completely newbie to gRPC. I have using HTTP4K for a few years now and I love its testability. I have just introduced HTTP4K to the place where I started working recently. gRPC is used extensively at this new place and I will need to make gRPC calls inside my HTTP4K application. I’m wondering what people’s experience are like to use gRPC inside a HTTP4K application? Any tips/advice? I’m thinking to adapt the underlying gRPC request & response to the

HTTPHandler

interface which can make testing easier (it is just an idea atm, not sure if this even makes sense). Do people have any other tips? Like what do you use for testing? Anything nice you use for recording and replying requests and responses? Thank you 🙏

So, I'm going to be working with protobuf messages for the next while. Is there any technical reason protobuf/avro isn't supported as an

http4k-format

module? Or has there just been no interest up until now?

I have a request that works with curl at the command line:

curl -A "ellens-user-agent" -X POST -d 'grant_type=password&username=USER&password=PASSWORD' --user 'SCRIPTID:SECRET' <https://www.reddit.com/api/v1/access_token>

How do I convert that into an

http4k

request?

Hello #http4k ! I have a question related to

http4k-contract

From http4k's documentation https://www.http4k.org/guide/reference/contracts/, the following example is shown

// this route has a dynamic path segment
fun greetRoute(): ContractRoute {

    // these lenses define the dynamic parts of the request that will be used in processing
    val ageQuery = <http://Query.int|Query.int>().required("age")
    val stringBody = Body.string(TEXT_PLAIN).toLens()

    // this specifies the route contract, with the desired contract of path, headers, queries and body parameters.
    val spec = "/greet" / Path.of("name") meta {
        summary = "tells the user hello!"
        queries += ageQuery
        receiving(stringBody)
    } bindContract GET

    // the this function will dynamically supply a new HttpHandler for each call. The number of parameters
    // matches the number of dynamic sections in the path (1)
    fun greet(nameFromPath: String): HttpHandler = { request: Request ->
        val age = ageQuery(request)
        val sentMessage = stringBody(request)

        Response(OK).with(stringBody of "hello $nameFromPath you are $age. You sent $sentMessage")
    }

    return spec to ::greet
}

The above example is fine for path with Path Lens as the last 'path component', however, for path that has string as the last 'path component', I must include a extra parameter for function

greet

, e.g.

// this route has a dynamic path segment
fun greetRoute(): ContractRoute {

    // these lenses define the dynamic parts of the request that will be used in processing
    val ageQuery = <http://Query.int|Query.int>().required("age")
    val stringBody = Body.string(TEXT_PLAIN).toLens()

    // this specifies the route contract, with the desired contract of path, headers, queries and body parameters.
    val spec = "/greet" / Path.of("name") / "foo" meta {
        summary = "tells the user hello!"
        queries += ageQuery
        receiving(stringBody)
    } bindContract GET

    // the this function will dynamically supply a new HttpHandler for each call. The number of parameters
    // matches the number of dynamic sections in the path (1)
    fun greet(nameFromPath: String, foo: String): HttpHandler = { request: Request ->
        val age = ageQuery(request)
        val sentMessage = stringBody(request)

        Response(OK).with(stringBody of "hello $nameFromPath you are $age. You sent $sentMessage")
    }

    return spec to ::greet
}

foo

's value is always

"foo"

in this case According to Stack Overflow https://stackoverflow.com/questions/53278208/how-do-you-model-a-path-parameter-in-the-middle-with-http4k, it seems that the inclusion of an extra parameter is unavoidable. I also checked http4k internal implementation, and class

ContractRouteSpec2

is the reason behind the required

foo: String

. I may replace

greet

with a lambda and put

_: String

instead of

foo: String

, but just before I do the refactoring, I wanna make sure it is the intended way to handle this problem. Sorry for the superrrrr long question, and thank you reading it all the way here.

How do you configure timeout for http4k client?

Is there any way to send a redirect in response to a websocket request?

Is there any way to authorize a WebSocket connection? It seems like the

WsFilter

only works with a

Websocket

that's already open. Is the only alternative to close the

Websocket

immediately after failing to validate the authorization?

Hi, is there a way to encode query params with a specific encoding, for instance UTF-8?

Hi, for

http4k-contract

, is it possible to generate array of enum query parameter, e.g.

"schema": {
              "type": "array",
              "items":{
                "type": "string",
                "enum": ["foo", "soo", "doo", "coo"]
              }
            }

Hi everyone! We're excited to tell you that http4k is headed back to KotlinConf in 2023! We'll be presenting Exploring the Testing Hyperpyramid with Kotlin and http4k to showcase a the unreasonable power of the Server as a Function model in your testing stack. We're also looking at options for a way for http4k users to meet at KC for questions or knowledge sharing on your favourite web toolkit. Watch this space! 🎉 See you in Amsterdam! 🎉

If I want to parse/construct path nodes in routes as I descend the route tree, how do I accomplish that? E.g.

routes(
  "/projects" bind routes(
    "/{projectId:\\d+}" bind { ... parse projectId here, yielding a RoutingHttpHandler that can access something constructed from the projectId ... }
  )
)

This pattern would be nested several more times:

/project/{projectId}/workspace/{workspaceId}/snippet/{snippetId}

, for instance

Hi Everyone. Just a quick note to announce that we have now released a new version of http4k and http4k-connect which support AWS Lambda Snapstart. Also, there was Kotlin meet-up in London yesterday with talks by Andrey Breslav (Kotlin language designer) and myself. The event was live-streamed and you can find the details below. Andrey's talk was especially interesting as it delved into the sources of inspiration for the Kotlin design (and more importantly what features were left out and why! 🙂 ): Details Andrey Breslav (@1h15m) Andrey Breslav led the design and development of the Kotlin Programming Language at JetBrains for 10 years. Andrey will be talking about the languages Kotlin learned from and will have plenty of time for Q and A - so prepare questions you'd like to ask the lead language designer of Kotlin :) David Denton: Smash Your Adapter Monolith With The Connect Pattern (@0h15m) Server-side code is regularly broken down into manageable chunks, based on endpoints. As a result, it tends to be nicely factored. But over several projects, we noticed that the same was not true of adapters that talk to 3rd party systems. These pieces of code tended to grow uncontrolled and were not given the same level of attention. We can use the power of Kotlin and take advantage of language features such as Data Classes, Companion Objects, Operator Overloading and Extension Functions to easily do this - but the pattern concepts themselves are applicable to any technology choice or programming model. You can watch it online here:

👋 Hello, team!

I have created a KMP library implementing http4k, but when I install it in a project I get the following message:

org.springframework.web.util.NestedServletException: Handler dispatch failed; nested exception is java.lang.NoClassDefFoundError: org/http4k/core/BodyMode$Stream

, can you help me, please?

@Fernando http4k doesn’t work in KMP, I’m afraid. It uses some JDK classes that aren’t multi-platform (around streaming and time manipulation)

We were waiting for possible replacements for those but haven’t checked for a while if they exist now

For those who've missed, you can take advantage of Lambda Snapstart with http4k.

Great research and post about http4k on Java advent today. And yes, we are looking at official Loom support. 😉 https://www.javaadvent.com/2022/12/asynchronous-functional-web-server-in-kotlin.html

Has anyone had any luck getting Google Sign In (or any implicit login flow) to work in their http4k-contract swagger ui?

val googleSecurity = ImplicitOAuthSecurity(
    Uri.of("<https://accounts.google.com/o/oauth2/v2/auth>"),
    listOf(OAuthScope("email")),
    Filter.NoOp // todo
)

val api = contract {
    renderer = OpenApi3(ApiInfo("My Api", "1")) // jackson renderer
    descriptionPath = "/openapi"
    routes += generateRoutes()
    security = googleSecurity
}

val ui = swaggerUi(
    descriptionRoute = Uri.of("/openapi"),
    displayOperationId = true,
    requestSnippetsEnabled = true
)

routes(api, ui)
    .asServer(SunHttp(8000))
    .start()

I can get as far as logging in to google and then being redirected back to

<app_host>/oauth2-redirect.html

, but then my app obviously doesn't have this

/oauth2-redirect.html

path that the Swagger UI seems to have chosen for me.

Status.UNKNOWN_HOST

and

Status.CONNECTION_REFUSED

are equal, is that intentional? Try this:

fun main() {
    println(Status.SERVICE_UNAVAILABLE == Status.UNKNOWN_HOST)
    println(Status.UNKNOWN_HOST == Status.CONNECTION_REFUSED)
}

Gives:

false
true

The reason is that they have the same

code

(503) and both are

clientGenerated

.

HI http4kers! Quick update for those of you that are running on Serverless AWS Lambda. As well as the the existing support for the various Lambda runtimes that we already supported (standard AWS (x86 and Graviton), custom http4k-JVM and GraalVM), we've just pushed support for running the http4k-JVM runtime on Graviton2 via the official http4k Docker Images. We've also upgraded the underlying infra so we're on the latest versions of Amazon Linux, Java (11,17,19) and Graal 🙃 This means you can take advantage of the both the better cost savings of Graviton and the http4k runtime to get better performance and lower memory footprint for less 💵 , even if you don't want to go all the way to compiling to native with GraalVM. There's a fully working example in the examples repo which uses Pulumi to setup the infrastructure, or you can go straight to the amd64 docker image repo to see how it works from the command line 🙂