io.pivotal.spring.cloud.service.eureka.SurgicalRoutingRequestTransformer.java Source code

Introduction

Here is the source code for io.pivotal.spring.cloud.service.eureka.SurgicalRoutingRequestTransformer.java

Source

/*
 * Copyright 2013-2015 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.pivotal.spring.cloud.service.eureka;

import java.util.Map;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerRequestTransformer;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpRequest;
import org.springframework.http.client.support.HttpRequestWrapper;

/**
 * Adds a surgical routing header to the request if CF App GUID and CF Instance
 * Index are present in metadata.
 * 
 * @see <a href=
 *      'https://docs.cloudfoundry.org/devguide/deploy-apps/routes-domains.html#surgical-routing'>
 *      https://docs.cloudfoundry.org/devguide/deploy-apps/routes-domains.html#
 *      surgical-routing</a>
 * 
 * @author William Tran
 */
public class SurgicalRoutingRequestTransformer implements LoadBalancerRequestTransformer {
    public static final String CF_APP_GUID = "cfAppGuid";
    public static final String CF_INSTANCE_INDEX = "cfInstanceIndex";
    public static final String SURGICAL_ROUTING_HEADER = "X-CF-APP-INSTANCE";

    @Override
    public HttpRequest transformRequest(HttpRequest request, ServiceInstance instance) {
        Map<String, String> metadata = instance.getMetadata();
        if (metadata.containsKey(CF_APP_GUID) && metadata.containsKey(CF_INSTANCE_INDEX)) {
            final String headerValue = String.format("%s:%s", metadata.get(CF_APP_GUID),
                    metadata.get(CF_INSTANCE_INDEX));
            // request.getHeaders might be immutable, so return a wrapper
            return new HttpRequestWrapper(request) {
                @Override
                public HttpHeaders getHeaders() {
                    HttpHeaders headers = new HttpHeaders();
                    headers.putAll(super.getHeaders());
                    headers.add(SURGICAL_ROUTING_HEADER, headerValue);
                    return headers;
                }
            };
        }
        return request;
    }

}