Hi, How would you recommend to handle the following need: I have an application which configures an ...

# ktor

[Olivier Patry]

Hi,
How would you recommend to handle the following need:
I have an application which configures an HttpClient to reach a REST API. This client is consumed through a business logic layer injected as a singleton in my DI graph (at app start).
I currently inject the HttpClient in this business logic ctor class.

I might need intermediate setup to fully configure this HttpClient, typically, I'll get the root URL of the REST API after being authorized/authenticated.
My business logic layer relies on "relative" endpoints, rest/api/foo/bar and I don't want to expose the root URL in this layer, which may vary depending on the DI setup (prod/preprod, specific setup…).

Until now, I didn't have the constraint of knowing the root URL afterwards, it was known at app start which is not the case anymore.
So, I'd like to update on the fly the defaultRequest block of the client ideally, is it the way to go, how?

[Olivier Patry]

Here is my defaultRequest initial impl

defaultRequest {
    if (url.host.isEmpty()) {
        val defaultUrl = URLBuilder().takeFrom(MY_DEFAULT_URL)
        url.host = defaultUrl.host
        url.protocol = defaultUrl.protocol
        if (!url.encodedPath.startsWith('/')) {
            // prepend base path from configuration
            val basePath = defaultUrl.encodedPath
            url.encodedPath = "$basePath/${url.encodedPath}"
        }
    }
}

[Aleksei Tirman [JB]]

You can try reconfiguring the DefaultRequest plugin by creating a new client using the HttpClient.config method. This solution requires the replacement of the HttpClient instance in the DI container.

[Olivier Patry]

Yes, replacing the HttpClient instance was the only solution I could think of but hardly usable in my current setup 😞

[Olivier Patry]

In the meantime, I thought about injecting a DefaultRequestDelegate or something like that which would delegate the lookup of the defaultRequest to another configurable entity, don't know if it's viable.
I could just expose this directly as a DefaultRequest.DefaultRequestBuilder being injected in the HttpClient used.
Sounds feasible/reasonable?

[Aleksei Tirman [JB]]

I can't find a way of doing that. Do you have an idea?

[Olivier Patry]

Like what is suggested to inject the loadTokens refreshTokens here https://ktor.io/docs/bearer-client.html#step5 the bearerTokenStorage is provided from outside and dynamic, I imagine something close to that but to provide the default request.

This defaultRequest lambda is called at each new request, right?

[Aleksei Tirman [JB]]

That's right.