How to direct HTTP requests using AWS CRT HTTP Client through proxy?

Question

I am using the AWS CRT HTTP Client in the AWS SDK for Java 2.x, and I do not see requests directed to my local proxy. I am creating the request via the following (Java 11) code:
```java
private static final SdkHttpClient httpClient = AwsCrtHttpClient.builder()
        .proxyConfiguration(ProxyConfiguration.builder().host("localhost").port(9001).build())
        .build();
SdkHttpRequest.Builder sdkHttpRequestBuilder;
// Conditional build logic removed
sdkHttpRequestBuilder = SdkHttpRequest.builder().uri(new URI(uri)).method(method);
SdkHttpRequest sdkHttpRequest = sdkHttpRequestBuilder
        .appendHeader(HttpHeaders.CONTENT_TYPE, ContentType.APPLICATION_JSON.getMimeType())
        .build();
HttpExecuteResponse response = httpClient.prepareRequest(HttpExecuteRequest.builder().request(sdkHttpRequest).build()).call();
```
Despite the changes I make to the `proxyConfiguration` argument, I can't get these requests proxied. What am I doing wrong as I try to generate these requests?
I am using aws-crt-client version 2.27.9.

The most relevant AWS documentation regarding this proxy configuration is found here: https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/http-configuration-crt.html#http-config-crt-proxy-ex

Flumenque · Accepted Answer

There was no issue with the client's proxy. This turned out to be a conflict with the default proxy settings used by Hoverfly.

The solution was to set the `proxyLocalHost` flag in the Hoverfly configuration to `true`. That's because the client's builder logic in the AWS CRT HTTP Client was reading Hoverfly's default values for the environment variable "http.nonProxyHosts" and then setting the client's proxy configuration to `null` with its builder logic. The workaround was to modify the Hoverfly configuration to set the `proxyLocalHost` flag to `true` like the following:

```java
@HoverflyCore(config = @HoverflyConfig(proxyLocalHost = true))
@ExtendWith(HoverflyExtension.class)
class MyTest {
// ...
```

This sets the `proxyLocalHost` environment variable to `""`, and it allows for the default AWS CRT HTTP Client to proxy to localhost.

How to direct HTTP requests using AWS CRT HTTP Client through proxy?

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