Request headers not applied to transport

[ssuukk]

Description
I'm trying to connect to Home Assistant MCP server, which uses "Authorization: Bearer xxxx" header for connection.

To Reproduce
Steps to reproduce the behavior:

Try to connect to HA MCP server using such transport:

        val haTransport = http.mcpSseTransport( "http://homeassistant.local:8123/mcp_server") {
            headers {
                append("Authorization", "Bearer some_token_here")
            }
        }

Gives: Error connecting to server: Expected status code 200 but was 401

Calling it via CURL works without a problem:

curl -H "Authorization: Bearer some_token_here" http://homeassistant.local:8123/mcp_server/sse
event: endpoint
data: /mcp_server/messages/01JQEXWJPKWPZPTFVEQRKS76BZ

Expected behavior
The header is passed and the server returns 200

[renxiawang]

Hmm, I can't reproduce it in a unit test:

@Test
fun `should read messages`() = runTest {
    val server = embeddedServer(CIO, port = PORT) {
        install(io.ktor.server.sse.SSE)
        val transports = ConcurrentMap<String, SseServerTransport>()
        routing {
            sse {
                mcpSseTransport("", transports).apply {
                    onMessage {
                        val customHeader = call.request.headers[HttpHeaders.Authorization]
                        // assert here with no problem
                        assertEquals("Bearer some_token_here", customHeader, "Expected ${HttpHeaders.Authorization} header value")
                        send(it)
                    }

                    start()
                }
            }

            post {
                mcpPostEndpoint(transports)
            }
        }
    }.start(wait = false)

    val client = HttpClient {
        install(SSE)
    }.mcpSseTransport {
        url {
            host = "localhost"
            port = PORT
        }

        // setting auth header
        headers.append(HttpHeaders.Authorization, "Bearer some_token_here")
    }

    testClientRead(client)
    server.stop()
}

[ssuukk]

can you connect, though? sob., 29 mar 2025, 22:12 użytkownik Renxia Wang ***@***.***> napisał:

…

Hmm, I can't reproduce it in a unit test: @testfun `should read messages`() = runTest { val server = embeddedServer(CIO, port = PORT) { install(io.ktor.server.sse.SSE) val transports = ConcurrentMap<String, SseServerTransport>() routing { sse { mcpSseTransport("", transports).apply { onMessage { val customHeader = call.request.headers[HttpHeaders.Authorization] // assert here with no problem assertEquals("Bearer some_token_here", customHeader, "Expected ${HttpHeaders.Authorization} header value") send(it) } start() } } post { mcpPostEndpoint(transports) } } }.start(wait = false) val client = HttpClient { install(SSE) }.mcpSseTransport { url { host = "localhost" port = PORT } // setting auth header headers.append(HttpHeaders.Authorization, "Bearer some_token_here") } testClientRead(client) server.stop() } — Reply to this email directly, view it on GitHub <#63 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAV3O6O7DNBUOEEDBHKM6IT2W4EFFAVCNFSM6AAAAAB2AFIKUGVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDONRUGI2DINRRGQ> . You are receiving this because you authored the thread.Message ID: ***@***.***> [image: renxiawang]*renxiawang* left a comment (modelcontextprotocol/kotlin-sdk#63) <#63 (comment)> Hmm, I can't reproduce it in a unit test: @testfun `should read messages`() = runTest { val server = embeddedServer(CIO, port = PORT) { install(io.ktor.server.sse.SSE) val transports = ConcurrentMap<String, SseServerTransport>() routing { sse { mcpSseTransport("", transports).apply { onMessage { val customHeader = call.request.headers[HttpHeaders.Authorization] // assert here with no problem assertEquals("Bearer some_token_here", customHeader, "Expected ${HttpHeaders.Authorization} header value") send(it) } start() } } post { mcpPostEndpoint(transports) } } }.start(wait = false) val client = HttpClient { install(SSE) }.mcpSseTransport { url { host = "localhost" port = PORT } // setting auth header headers.append(HttpHeaders.Authorization, "Bearer some_token_here") } testClientRead(client) server.stop() } — Reply to this email directly, view it on GitHub <#63 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAV3O6O7DNBUOEEDBHKM6IT2W4EFFAVCNFSM6AAAAAB2AFIKUGVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDONRUGI2DINRRGQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[renxiawang]

@ssuukk Yes. I am able to see a log on the MCP server side saying creating session when starting the client

val client = HttpClient {
        install(SSE)
}.mcpSseTransport(urlString = "http://localhost:8123/mcp_server") {
       headers.append(HttpHeaders.Authorization, "Bearer my-token")
}

[ssuukk]

No luck for me. Maybe the receiving server is buggy.