Change auth credentials in KTor client - ktor

Question

How can I change the credentials in a KTor client?
The Auth feature needs to be installed when the client is created. I've tried doing it later but it seems not to work, either as a first time setup or a repeat.
The docs suggest holding onto the client once it's created as the setup is expensive, so it seems unduly restrictive not to be able to change the credentials (& surely the smart folks at JetBrains wouldn't have done that).
I have an answer which works, to my surprise, but I'm not sure it's a good answer. Comments welcome.
Because the docs say that creating the client is expensive I've put it in a singleton and then I've done something like this
#ThreadLocal
Object ServerLink {
fun setClient(id:String, pw:String) {
// Create the client here and set id and pw
}
}
Then I simply call ServerLink.setClient(newId, newPW) whenever I want. Yes this works, and I didn't think I'd got multiple threads, but won't this be a memory leak, or at least memory waste?

Answer 1

You can do it by getting a reference to Auth feature and mutating its list of providers. Here is an example of changing Basic authentication credentials after client creation:
val client = HttpClient(CIO) {
install(Auth) {
basic {
username = "user"
password = "password"
}
}
}
val auth = client.feature(Auth)
if (auth != null) {
auth.providers.removeAt(0)
auth.basic {
username = "new-user"
password = "new-password"
}
}
val r = client.get<String>("http://httpbin.org/basic-auth/new-user/new-password")
println(r)

Answer 2

With ktor version 2.2.1 I managed to update the bearer token credentials like this:
const val REFRESH_TOKEN = "" // not required
val client = HttpClient(CIO) {
Auth {
bearer {
sendWithoutRequest { true }
loadTokens { BearerTokens(initialToken, REFRESH_TOKEN) }
}
}
}
fun updateBearerCredentials(newToken: String) {
client.plugin(Auth).bearer {
loadTokens { BearerTokens(newToken, REFRESH_TOKEN) }
}
}
I assume the same works for basic auth. Have not tested it though.