Simple Reverse Proxy with Spring Boot and Netflix Zuul

Question

I'm looking to implement a simple reverse proxy with Spring Boot that is:

• Easy to add routes
• Ability to add custom authentication on a per route basis
• Add additional headers as needed

I've looked at the facilities provided by the @EnableZuulProxy annotation but it seems too heavyweight as I don't have a desire to use Eureka, Ribbon, or Hystrix. However, @EnableZuulServer is a bit light on configuration.

Would anyone be able to provide an example of what I'm after? Is Netflix Zuul the right choice for this or is there another library I should be looking at?

Thanks!

Solution 1

Simple Reverse Proxy Server

It's easy to set up a simple proxy reverse using Spring Boot without Ribbon, Eureka, or Hystrix.

Simply annotate your main application class with @EnableZuulProxy and set the following property in your configuration:

ribbon.eureka.enabled=false

Then define your routes in your configuration like such:

zuul.routes.<route_name>.path=<route_path>    
zuul.routes.<route_name>.url=http://<url_to_host>/

where <route_name> is an arbitrary name for your route and <route_path> is a path using Ant-style path matching.

So a concrete example would be something like this

zuul.routes.userservice.path=users/**
zuul.routes.userservice.url=http://localhost:9999/

Custom Filters

You can also implement your custom authentication and any additional headers by extending and implementing the ZuulFilter class and adding it as an @Bean to your @Configuration class.

So another concrete example:

public class MyFilter extends ZuulFilter {

  @Override
  public String filterType() {
    // can be pre, route, post, and error
    return "pre";
  }

  @Override
  public int filterOrder() {
    return 0;
  }

  @Override
  public boolean shouldFilter() {
    return true;
  }

  @Override
  public Object run() {
    // RequestContext is shared by all ZuulFilters
    RequestContext ctx = RequestContext.getCurrentContext();
    HttpServletRequest request = ctx.getRequest();

    // add custom headers
    ctx.addZuulRequestHeader("x-custom-header", "foobar");    

    // additional custom logic goes here

    // return isn't used in current impl, null is fine
    return null;
  }

}

and then

@Configuration
public class GatewayApplication {

  @Bean
  public MyFilter myFilter() {
    return new myFilter();
  }

}

Solution 2

Zuul is a good choice. Am not sure about other alternatives but, we've started building Zuul filters (Pre/Post and Route) that could intercept the request and do all pre/post processing and route based upon your need. It is not mandatory to use the whole bunch of Eureka, Ribbon and Hysterix along with Zuul.

Comments

[Centinul]

Would you be able to provide any examples of routing a request to a different origin?

[yathirigan]

we are trying to implement this by refering to the URL patterns that can be defined in application.yml cloud.spring.io/spring-cloud-netflix/spring-cloud-netflix.ht‌​ml

[Centinul]

@yahthirigan are you writing a custom "pre" filter to parse the YAML file? If so are you then passing that in to a "route" filter that was already defined by the spring-cloud-netflix project?

[yathirigan]

our pre-filters do not parse the YAML but does certain operations on the incoming requests.. something like your requirement of adding custom headers. We then leave it to the already existing route filter to route it to the actual end point as configured in the zuul routes.