Spring Cloud Learning Route (7) - Unified Gateway Gateway

I. Introduction

(1) Requirements: The microservices in the server are only allowed to be called by internal personnel or intranet personnel, and access by external network personnel is denied.

(2) How to realize the demand? gateway

(3) Functions of the gateway

Identity authentication and permission verification
Service routing, load balancing
request throttling

(4) Technical realization of the gateway

Spring Cloud provides two gateway implementations:

Spring Cloud Gateway , based on WebFlux provided in Spring 5, is an implementation of responsive programming with better performance.
zuul —— Based on Servlet implementation, it belongs to blocking programming.

Second, the basic use of Gateway

(1) Building a gateway service

1. Common new modules, introduce SpringCloudGateway dependencies and nacos service discovery dependencies

<!--网关依赖-->
<dependency>
	<groupId>org.springframework.cloud</gourpId>
	<artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<!--nacos服务发现依赖-->
<dependency>
	<groupId>com.alibaba.cloud</gourpId>
	<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>

2. Create a gateway service

@SpringBootApplication
public class GatewayApplication{
    
    
	public static void main(String[] args) {
    
    
		SpringApplicaiton.run(GatewayApplication.class,args);
	}
}

3. Implement gateway routing

Configure routing configuration

server:
	port: 10010 #网关端口
spring:
	application:
		name: gateway #服务名称
	cloud:
		nacos:
			server-addr: localhost:8848 #nacos地址
		gateway:
			routes: #网关路由配置
				- id: user-service #路由id，自定义只要唯一即可
				  # uri: http://127.0.0.1:8081 #路由的目标地址 http是固定地址
				  uri: lb://userservice #路由目标地址，lb是负载均衡，后面是服务名称
				  predicates: # 路由断言，判断请求是否符合路由规则的条件
					- Path=/user/** # 这个是按照路径匹配，只要以 /user/ 开头就符合要求

Summarize:

How to configure the gateway
- Introduce gateway dependency, nacos service discovery dependency
- Configure application, including basic service information, nacos address, routing
routing configuration
- id : the unique identifier of the route
- uri : routing destination, supports both lb and http
- predicates : Routing assertion, to judge whether the request meets the requirements and forward it to the routing destination
- filters : route filters, processing requests and responses

Three, the assertion factory Route Predicate Factory

(1) The purpose of using the assertion factory

The assertion rules in the configuration file are only strings, and these strings will eventually be read and processed by the Predicate Factory , turning them into conditions for routing judgments.

(2) The basic assertion factory provided by Spring

name	illustrate	example
After	is a request after a certain point in time	- After=2037-01-20T17:42:47.489-07:00[America/denver]
Before	is a request before a certain point in time	- Before=2037-01-20T17:42:47.489-07:00[America/denver]
Between	is a request before some two time points	- Between=2037-01-20T17:42:47.489-07:00[America/denver], 2099-01-20T17:42:47.489-07:00[America/denver]
Cookie	Requests must contain certain cookies	- Cookie=chocolate, ch.p
Header	The request must contain certain Headers	- Header=X-Request-id,\d+
Host	The request must be to access a certain host (domain name)	- Host=.somehost.org,.anotherhost.org
Method	The request method must be specified	- Method=GET,POST
Path (commonly used)	The request path must conform to the specified rules	- Path= /red/(segment),/blue/**
Query	The request parameters must contain the specified parameters	- Query=name.jack or -Query=name
RemoteAddr (commonly used)	Requester IP must be in the specified range	- RemoteAddr=192.168.1.1/24
Weight	weight processing

(3) Summary

What is the role of PredicateFactory?
Read user-defined assertion conditions and make judgments on requests
What does Path=user/** mean?
Paths starting with /user/ are considered to be in compliance

4. Filter factory

(1) Route filter GatewayFilter

GatewayFilter is a filter in the gateway, which can process the request entering the gateway and the response returned by the microservice.

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(2) Commonly used filter factories

Spring provides 31 different route filter factories.

Common filter factory list

name	illustrate
AddRequestHeader	Add a request header to the current request
RemoveRequestHeader	Remove a request header from the request
AddResponseHeader	Add a response header to the response result
RemoveResponseHeader	Remove a response header from the response result
RequestRateLimiter	Limit request traffic

(3) Summary

What does the filter do?
- Process the routed request or response
- The filter configured under the route only takes effect for the request of the current route
What is the role of defaultFilters?
- A filter that applies to all routes

5. Global filter

(1) Global Filter GlobalFilter

The role of the global filter is to process all requests and microservice responses entering the gateway, which is consistent with the role of GatewayFilter.

What is the difference between a global filter and a Gateway?
GatewayFilter is defined through configuration, and the processing logic is fixed.
The logic of GlobalFilter is implemented through code.

(2) Realize GlobalFilter

This is done by implementing a GlobalFilter.

public interface GlobalFilter{
    
    
	/**
	* 处理当前请求，有必要的话通过{@link GatewayFilterChain}将请求交给下一个过滤器处理
	* @param exchange 请求上下文，里面可以获取Request、Response等信息
	* @param chain 用来把请求委托给下一个过滤器
	* @return {@code Mono<Void>} 返回标识当前过滤器业务结束
	* */
	Mono<Void> filter(ServerWevExchange exchange, GatewayFilterChain chain);
}

(3) Example

@Order(-1)
@Component
public class AuthorizeFilter implements GlobalFilter {
    
    
	@Override
	Mono<Void> filter(ServerWevExchange exchange, GatewayFilterChain chain){
    
    
		//1、获取请求参数
		ServerHttpRequest = exchange.getRequest();
		MultiValueMap<String,String> params = request.getQueryParams();
		//2、获取参数中的 authorization 参数
		String auth = params.get("authorization "):
		//3、判断参数值是否为admin
		if("admin".equals(auth)){
    
    
			//4、若是则放行
			return chain.filter(exchange);
		}
		//5、若否则设置状态码并拦截
		exchange.getResponse().setStatusCode(HttpStatus.UNAUTHORIZED);
		return exchange.getResponse().setComplete();
	}
}

(4) Summary

What does the global filter do?
A filter that works on all routes, and can customize the processing logic
Steps to implement a global filter?
- Implement the GlobalFilter interface
- Add @Order annotation or implement Ordered interface
- write processing logic

6. Execution order of filters

Gateway filters learned so far: current route filter , DefaultFilter , GlobalFilter

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(1) The reason why the filter can be sorted and executed

All filters will be adapted through AddRequestHeaderGatewayFilterFactory class, the result of adaptation is GatewayFilter, and all filters can be sorted and executed.

(2) Filter sorting rules

Each filter must specify an order value of int type, the smaller the order value, the higher the priority, and the higher the execution order
GlobalFilter specifies the order value by implementing the ordered interface or adding an Order annotation.
The order of routing filter and defaultFilter is specified by Spring, and the order of declaration is incremented from 1 by default.
When the filter order values are the same, execute in the order of DefaultFilter > Route Filter > GlobalFilter .

7. Cross-domain issues

(1) What is the cross-domain problem?

Inconsistent domain names are cross-domain, mainly including:

The domain name is different , www.taobao.com - www.taobao.org or www.jd.com - miaosha.jd.com.
The ports are different , localhost:8080 - localhost:8081.

(2) Causes of cross-domain problems

The browser prohibits cross-domain Ajax requests between the request initiator and the server , and the request is intercepted by the browser.

(3) Solution: CORS

Configure the CORS scheme

spring:
	cloud:
		gateway:
			globalcors: #全局的跨域处理
				add-to-simple-url-handler-mapping: true # 解决options请求被拦截问题
				corsConfigurations:
					'[/**]':
						allowedOrigins: #允许地址请求
							- “http://localhost:8090”
							-  "http://www.leyou.com"
						allowedMethods: # 允许跨域ajax的请求方式
							- "GET"
							- "POST"
							- "DELETE"
							- "PUT"
							- "OPTIONS"
						allowedHeaders: "*" # 允许在请求中携带的头信息
						allowedCredentials: true # 是否允许携带Cookie
						maxAge: 360000 # 跨域检测的有效期

Spring Cloud Learning Route (7) - Unified Gateway Gateway

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