Proxy setup

In some place Telegram Bots API will be unavailable. In this case all examples will just throw exception like:

Exception in thread "main" java.net.ConnectException: Connection refused
	at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
	at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
	at io.ktor.network.sockets.SocketImpl.connect$ktor_network(SocketImpl.kt:36)
	at io.ktor.network.sockets.SocketImpl$connect$1.invokeSuspend(SocketImpl.kt)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:571)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:738)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:678)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:665)

Process finished with exit code 1

There are several ways to solve this problem:

  • Built-in proxy config (will require some socks or http proxy server)
  • System-configured VPN or proxy

Using Ktor Client built-in proxy

First of all, you will need to use one more library:

build.gradle:

implementation "io.ktor:ktor-client-okhttp:1.4.1"

Dependency note
In the snippet above was used version 1.4.1 which is actual for TelegramBotAPI at the moment of filling this documentation (Oct 4 2020, TelegramBotAPI version 0.29.0) and you can update version of this dependency in case if it is outdated.

For configuring proxy for your bot inside your program, you can use next snippet:

val botToken = "HERE MUST BE YOUR TOKEN"
val bot = telegramBot(botToken) {
  ktorClientEngineFactory = OkHttp
  proxy = ProxyBuilder.socks("127.0.0.1", 1080)
}

Explanation line by line:

  1. val botToken = "HERE MUST BE YOUR TOKEN" - here we are just creating variable botToken
  2. val bot = telegramBot(botToken) { - start creating bot
  3. ktorClientEngineFactory = OkHttp - setting up engine factory of our bot. On the time of documentation filling, OkHttp is one of the engines in Ktor system which supports socks proxy. More you can read on Ktor site in subparts about engines and proxy
  4. proxy = ProxyBuilder.socks("127.0.0.1", 1080) - here we are setting up our proxy. Here was used local server which (as assumed) will connect to server like shadowsocks

Next steps