Hello everyone! I am developing a project that I ...

# ktor

[Jari Ruokonen]

Hello everyone!

I am developing a project that I inherited and it uses Ktor.

After upgrading Ktor from 1.4.2 to 1.6.8, I ran into a weird issue with unit tests. Following is an example test, but they all fail the same with 404 error.

@Test
    fun `400 Bad request on item sync when request body cannot be parsed`() {
        val invalidItem = "invalid body"
        withTestApplication({
            restService(connector, synchronizer, logger)
        }) {
            handleRequest(true) {
                method = <http://HttpMethod.Post|HttpMethod.Post>
                uri = "/synchronize/item"
                setBody(invalidItem)
            }.apply {
                assertEquals(HttpStatusCode.BadRequest, response.status())
            }
        }
    }

This particular test fails with following status:

expected: <400 Bad Request> but was: <404 Not Found>
Expected : 400 Bad Request
Actual : 404 Not Found

If I place breakpoints to the tested restService code, they are never reached, like the 404 error hints. I also placed breakpoint to start() method of the RestService and it's being called at the start of the test as expected and I can step through it without errors.

If I revert Ktor back to 1.4.2, all the tests run ok - so, what exactly could have changed from 1.4.2 to 1.6.8 that breaks these? The change log is quite lengthy, so I ask for an educated advise.

[Aleksei Tirman [JB]]

It’s hard to say what can cause that. What is the implementation of the restService ?

[Jari Ruokonen]

I'll paste that first thing tomorrow. Don't have the code available now.

I guess something goes wrong in the start-up of the service, but it doesn't leave any errors to log.

[Jari Ruokonen]

fun Application.restService(
    connector: Connector,
    synchronizer: SynchronizationManager,
    logger: Logger
) {
    install(ContentNegotiation) {
        gson {
            setDateFormat(DateFormat.LONG)
            setPrettyPrinting()
        }
    }
    install(DefaultHeaders)
    install(CallLogging)

    val prometheusRegistry = PrometheusMeterRegistry(PrometheusConfig.DEFAULT)
    install(MicrometerMetrics) {
        registry = prometheusRegistry
    }

    install(Routing) {
        get("/metrics") {
            call.respond(prometheusRegistry.scrape())
        }
        route("/synchronize") {
            synchronizationRest(connector, synchronizer, logger)
        }
    }
}

There goes, as I said, nothing special.

Routing is defined like this:

fun Route.synchronizationRest(connector: Connector, synchronizer: SynchronizationManager, logger: Logger) {

    route("/item") {

        post("/") {
            try {
                ...handling is done here, likely irrelevant, as this is never reached when using Ktor 1.6.8...
                }
            } catch (e: Exception) {
                return@post call.respond(HttpStatusCode.BadRequest, e.localizedMessage)
            }
        }
    }
... other routes
}

[Jari Ruokonen]

I am in process of pinpointing which Ktor version jump is the exact one that breaks this. Could help to locate the problem, but sure is tedious chore to do.

[Aleksei Tirman [JB]]

The problem is in the missing trailing / in the URL of the handleRequest call. Since 1.5.0, Ktor starts distinguish routes with trailing slash and without it. You can use the IgnoreTrailingSlash plugin to make routes with and without a trailing slash indistinguishable.

[Jari Ruokonen]

Thanks! I was sure it was something trivial, but just didn't know what.