LoadBalancedUrlFilter

LoadBalancedUrlFilter.java

import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.netflix.zuul.filters.ZuulProperties;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

import javax.servlet.http.HttpServletRequest;
import java.net.URL;

/**
 * @author Thibaud Leprêtre
 */
@Component
public class LoadBalancedUrlFilter extends ZuulFilter {

    private final ZuulProperties properties;

    @Autowired
    public LoadBalancedUrlFilter(ZuulProperties properties) {
        this.properties = properties;
    }

    @Override
    public String filterType() {
        return "pre";
    }

    @Override
    public int filterOrder() {
        return 10;
    }

    @Override
    public boolean shouldFilter() {
        RequestContext ctx = RequestContext.getCurrentContext();
        return !ctx.containsKey("serviceId") && ctx.getRouteHost() != null;
    }

    @Override
    public Object run() {
        RequestContext ctx = RequestContext.getCurrentContext();
        URL url = ctx.getRouteHost();
        String serviceId = url.getHost();

        ctx.set("serviceId", serviceId);
        ctx.setRouteHost(null);
        ctx.addOriginResponseHeader("X-Zuul-ServiceId", serviceId);
        String path = !ctx.containsKey("requestURI") ? "" : (String) ctx.get("requestURI");
        ctx.set("requestURI", (url.getPath() + path).replace("//", "/"));

        if (properties.isAddProxyHeaders()) {
            HttpServletRequest request = ctx.getRequest();
            String prefix = (request.getHeader("X-Forwarded-Prefix") == null)
                    ? "" : request.getHeader("X-Forwarded-Prefix");
            String newPrefix = url.getPath() + prefix;
            if (StringUtils.hasText(newPrefix) && !newPrefix.equals("/")) {
                ctx.addZuulRequestHeader("X-Forwarded-Prefix", newPrefix.replace("//", "/"));
            }
        }
        return null;
    }
}