How to Specify custom filter in application.yml Spring Cloud Gateway

Instead of implementing GatewayFilter you should implement GatewayFilterFactory

and make it a Component:

@Component
public class MyGatewayFilter implements GatewayFilterFactory {

Then you can refer to it by the bean name in your route.

filters:
- MyGatewayFilter

The documentation on this isn't very good at the moment. I was only able to figure this out by looking at the source code for spring-cloud-gateway on github

You need to implement GatewayFilterFactory

@Component
public class DemoGatewayFilter implements GatewayFilterFactory<DemoGatewayFilter.Config> {

    @Override
    public GatewayFilter apply(Config config) {
        return (exchange, chain) -> {
            System.out.println("gateway filter name "+config.getName());
            return chain.filter(exchange);
        };
    }

    @Override
    public Config newConfig() {
        return new Config("DemoGatewayFilter");
    }

    public static class Config {

        public Config(String name){
            this.name = name;
        }
        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}

and in application.yml file

 spring:
  application:
  cloud:
    gateway:
      routes:
      - id: MayApplication
        uri: http://myapplication:8080
        predicates:
        - Path=/apipath/to/filter/**
        filters:
          - DemoGatewayFilter