Feature: Add proxy handler for client API

[pizzaeueu]

Hi there!
My attempt to provide a solution for #101

Why PR to zio-http 2.x ?

Actually, I don't know the right flow. Please correct me if I need to do it in a different way. I personally need it in 2.x, so that was a motivation 😌

How did you test it?

1. Run locally any free forward-proxy, e.g. https://github.com/clue/docker-polipo
2. Run the following code with updated zio-http version

import zhttp.http.{Proxy, Request, URL}
import zhttp.service.Client.Config
import zhttp.service.{ChannelFactory, Client, EventLoopGroup}
import zio.ZIO

object Main extends zio.ZIOAppDefault {
  override def run = {
    val req = Request(
      url = URL
        .fromString("https://gorest.co.in/public/v2/posts")
        .toOption
        .getOrElse(URL.empty)
    )
    val proxy = Proxy(
      URL.fromString("http://127.0.0.1:8123").toOption.get
    )
    Client
      .request(
        req,
        Config().withProxy(proxy),
      )
      .provide(
        ChannelFactory.auto,
        EventLoopGroup.auto(),
      )
      .flatMap(response => ZIO.log(response.status.toString))
  }
}

Result with Proxy

timestamp=2022-04-24T07:28:44.302564Z level=INFO thread=#zio-fiber-2 message="Ok" location=test.Main.run file=Main.scala line=26

Result without Proxy

timestamp=2022-04-24T07:30:29.919041Z level=INFO thread=#zio-fiber-2 message="Ok" location=test.Main.run file=Main.scala line=26

Results with wrong proxy address

... java.nio.channels.UnresolvedAddressException: java.nio.channels.UnresolvedAddressException ...

... Connection refused: /127.0.0.1:1111

etc

[tusharmath]

Suggested change

	headers: Option[Headers] = None,
	headers: Headers = Headers.empty,

[codecov-commenter]

Codecov Report

Merging #1226 (3e99fdc) into main (15c32be) will increase coverage by 2.12%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1226      +/-   ##
==========================================
+ Coverage   59.59%   61.71%   +2.12%     
==========================================
  Files          70       71       +1     
  Lines        2450     2756     +306     
  Branches       70       92      +22     
==========================================
+ Hits         1460     1701     +241     
- Misses        990     1055      +65     

Impacted Files	Coverage Δ
zio-http/src/main/scala/zhttp/http/Proxy.scala	100.00% <100.00%> (ø)
zio-http/src/main/scala/zhttp/service/Client.scala	92.04% <100.00%> (+0.97%)	⬆️
...io-http/src/main/scala/zhttp/service/package.scala	100.00% <100.00%> (ø)
...io-http/src/main/scala/zhttp/http/PathSyntax.scala	91.30% <0.00%> (-8.70%)	⬇️
zio-http/src/main/scala/zhttp/service/Server.scala	42.37% <0.00%> (-4.30%)	⬇️
...io-http/src/main/scala/zhttp/service/Handler.scala	71.79% <0.00%> (-2.12%)	⬇️
zio-http/src/main/scala/zhttp/http/Cookie.scala	80.95% <0.00%> (-1.53%)	⬇️
zio-http/src/main/scala/zhttp/http/Path.scala	79.72% <0.00%> (+0.56%)	⬆️
zio-http/src/main/scala/zhttp/http/URL.scala	91.50% <0.00%> (+4.55%)	⬆️
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 15c32be...3e99fdc. Read the comment docs.

[tusharmath]

@pizzaeueu Can you make the PR wrt main. We make a ZIO 2.0 branch only at the time of release.

[pizzaeueu]

Hi @tusharmath
Thanks for the feedback

Target branch was changed to main
All conflicts were fixed

[pizzaeueu]

Hi @tusharmath
Sorry for disturbing you, but are there any chances to merge this MR?
Maybe I should apply any additional fixes or smth?

I really need such feature 😌