Ktor HTTP client allows using proxy in multiplatform code. The following document describes how to configure a proxy in ktor.

Multiplatform configuration

Create proxy

You don’t need to include additional artifacts to create a proxy. The supported proxy types are specific to a client engine. Two types of proxy can be configured in multiplatform: HTTP and SOCKS.

To create a proxy configuration use builders in the ProxyBuilder factory:

// Create http proxy
val httpProxy = ProxyBuilder.http("http://my-proxy-server-url.com/")

// Create socks proxy
val socksProxy = ProxyBuilder.socks(host = "127.0.0.1", port = 4001)

Proxy authentication and authorization are engine specific and should be handled by the user manually.

Set proxy

Proxy can be configured in multiplatform code using ProxyConfig builder in HttpClientEngineConfig block:

val client = HttpClient() {
    engine {
        proxy = httpProxy
    }
}

Platform-specific configuration

Jvm

The ProxyConfig class maps to Proxy class on the jvm:

val httpProxy = Proxy(Proxy.Type.HTTP, InetSocketAddress(4040))

The most of Jvm client engines support it out of the box.

Note: Apache and CIO engines support HTTP proxy only. Jetty client engine doesn’t support any proxy.

Native

The native ProxyConfig class can use url to determine proxy address:

val socksProxy = ProxyConfig(url = "socks://my-socks-proxy.com/")

Supported proxy types are engine specific. To see supported URLs consult with engine provider documentation:

• Curl: https://curl.haxx.se/libcurl/c/CURLOPT_PROXY.html
• iOS: https://developer.apple.com/documentation/foundation/nsurlsessionconfiguration/1411499-connectionproxydictionary

Js

The proxy configuration is unsupported by platform restrictions.