Configure java netty HttpClient to use a proxy server in spring boot

LocalProxyConfig.java

/**
 * A helper class to configure a http proxy.
 *
 * Spring autoconfigures this as it implements HttpClientCustomizer for gateway
 * outbound requests, but any webclient must manually call this.
 */
@Component
public class LocalProxyConfig implements HttpClientCustomizer {
 
    @Override
    public HttpClient customize(HttpClient httpClient) {
        // Configure http proxy.
        if (StringUtils.isNotBlank(System.getProperty("http.proxyHost"))) {
            httpClient = httpClient.resolver(new LocalProxyNameResolverGroup(
                    System.getProperty("http.proxyHost"),
                    Integer.parseInt(System.getProperty("http.proxyPort", "80"))));
        }
        return httpClient;
    }
 
    @AllArgsConstructor
    public final class LocalProxyNameResolverGroup extends AddressResolverGroup<InetSocketAddress> {
        private final String proxyHost;
        private final Integer proxyPort;
 
        @Override
        protected AddressResolver<InetSocketAddress> newResolver(EventExecutor executor) throws Exception {
            return new LocalProxyInetSocketAddressResolver(executor, proxyHost, proxyPort);
        }
    }
 
    public class LocalProxyInetSocketAddressResolver extends AbstractAddressResolver<InetSocketAddress> {
        private final String proxyHost;
        private final Integer proxyPort;
 
        public LocalProxyInetSocketAddressResolver(EventExecutor executor, String proxyHost, Integer proxyPort) {
            super(executor, InetSocketAddress.class);
            this.proxyHost = proxyHost;
            this.proxyPort = proxyPort;
        }
 
        @Override
        protected boolean doIsResolved(InetSocketAddress address) {
            return !address.isUnresolved();
        }
 
        @Override
        protected void doResolve(final InetSocketAddress unresolvedAddress, final Promise<InetSocketAddress> promise)
                throws Exception {
            try {
                promise.setSuccess(new InetSocketAddress(SocketUtils.addressByName(proxyHost), proxyPort));
            } catch (Exception e) {
                promise.setFailure(e);
            }
        }
 
        @Override
        protected void doResolveAll(final InetSocketAddress unresolvedAddress,
                final Promise<List<InetSocketAddress>> promise) throws Exception {
            try {
                promise.setSuccess(List.of(new InetSocketAddress(SocketUtils.addressByName(proxyHost), proxyPort)));
            } catch (Exception e) {
                promise.setFailure(e);
            }
        }
    }
}