BE: Make webclients use system proxy (#3881)

Co-authored-by: Ilya Kuramshin <iliax@proton.me>

kafka-ui-api/src/main/java/com/provectus/kafka/ui/util/GithubReleaseInfo.java

@@ -3,7 +3,6 @@ package com.provectus.kafka.ui.util;
 import com.google.common.annotations.VisibleForTesting;
 import java.time.Duration;
 import lombok.extern.slf4j.Slf4j;
-import org.springframework.web.reactive.function.client.WebClient;
 import reactor.core.publisher.Mono;
 
 @Slf4j
@@ -31,7 +30,7 @@ public class GithubReleaseInfo {
 
   @VisibleForTesting
   GithubReleaseInfo(String url) {
-    this.refreshMono = WebClient.create()
+    this.refreshMono = new WebClientConfigurator().build()
         .get()
         .uri(url)
         .exchangeToMono(resp -> resp.bodyToMono(GithubReleaseDto.class))

kafka-ui-api/src/main/java/com/provectus/kafka/ui/util/WebClientConfigurator.java

@@ -5,11 +5,8 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import com.provectus.kafka.ui.config.ClustersProperties;
 import com.provectus.kafka.ui.exception.ValidationException;
-import io.netty.buffer.ByteBufAllocator;
-import io.netty.handler.ssl.JdkSslContext;
 import io.netty.handler.ssl.SslContext;
 import io.netty.handler.ssl.SslContextBuilder;
-import io.netty.handler.ssl.SslProvider;
 import java.io.FileInputStream;
 import java.security.KeyStore;
 import java.util.function.Consumer;
@@ -93,7 +90,12 @@ public class WebClientConfigurator {
     // Create webclient
     SslContext context = contextBuilder.build();
 
-    builder.clientConnector(new ReactorClientHttpConnector(HttpClient.create().secure(t -> t.sslContext(context))));
+    var httpClient = HttpClient
+        .create()
+        .secure(t -> t.sslContext(context))
+        .proxyWithSystemProperties();
+
+    builder.clientConnector(new ReactorClientHttpConnector(httpClient));
     return this;
   }