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effect

• Unified management, easy monitoring
• Security and current limiting: Filter out illegal information at the gateway layer
• nginx external gateway, gateway intranet
• nginx can be enhanced using Lua or Kong

concept

• id: any name
• uri: The service address being proxied. id and uri are required, predicate and filter are optional
• Predicate: can be used to match the URI of the gateway. If it matches, the current route will take effect.
• Filter: An instance of GatewayFilter, which adds logic before or after the proxy, with the highest flexibility

Processing Flow

• First, Handler Mapping processes the URL and then hands it to Web Handler, which calls the first half of the filter for processing. After the processing is completed, it calls the real proxied service. After the proxied service responds, it executes the logic of the second half of the filter and returns the result to WebHandler, then to HandlerMapping, and finally to the client.

use

gateway:
      discovery:
        locator:
          enabled: true # 启用自动根据服务ID生成路由
          lower-case-service-id: true # 设置路由的路径为小写的服务ID
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yml configuration

• If the elements in the list have multiple fields, you need to use "-" and colon to specify each field and value respectively; if there is only one field, you can use commas to separate them.
• Object type configuration, you can use "-" and colon to configure each field
• Map type: key and value are separated by colons

predicates:
  - Path=/sendOrder
  - Query=name,ma.
  - name: Query
    args:
      param: id
      regexp: d+
 #predicates是List, 它的元素是
 public class PredicateDefinition {

	@NotNull
	private String name;

	private Map<String, String> args = new LinkedHashMap<>();
  }
  等号分割转成对象的写法不是yml内置支持的
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predicate

• The predicate configuration is a List, in which the elements can be strings in a specific format, or objects. String writing: equal sign separation, the first part is the predicate name, the second part args is comma-separated, the value is saved in Map value, and Map key is automatically generated. Object writing: PredicateDefinition
• If args contains commas and colons, you cannot use string formatting.
• The shortcutType method defines how to parse the args parameter to ConfigClass. DEFAULT: shortcutFieldOrder minus the shortcutFieldPrefix prefix corresponds to the ConfigClass field name, and the val of the args parameter corresponds to the field value of ConfigClass; GATHER_LIST: a comma-separated List; GATHER_LIST_TAIL_FLAG: a comma-separated List, but the last value is a Boolean value, and is eventually converted into a Map with 2 keys. The value of the first key is the List before the Boolean value, and the second is the Boolean value.
• Used to match requests to access the gateway (such as URI, query parameters, request headers). If a match is made, the current route will take effect.
• Corresponding to the implementation of GatewayPredicate, the implementation class is created by the factory. The factory is the implementation class of RoutePredicateFactory. The implementation class naming convention is: predicate name + RoutePredicateFactory, for example, Path corresponds to PathRoutePredicateFactory
• The predicate name corresponds to the class name prefix of the factory implementation class, and the predicate parameter args corresponds to the factory ConfigClass
• Multiple predicates areandRelationship
• When the predicate does not pass, the gateway returns 404

Path

• Match paths, support ant matching and extract uriVariables through {}

Query

• Is there a corresponding http request parameter name? The value can be regular.
• name is fixed Query, args has 2 values, param and regexp, corresponding to the query parameter name and value
• When only the name is specified, it means that the request parameter will be passed.

Header

• HeaderRoutePredicateFactory
• Match the name and value of the request header. You can only match the name. There may be multiple values ​​in the actual request header. As long as there is a match, the configuration value supports regular expressions.

Method

• Matches HTTP request methods. Configuration must be uppercase and separated by commas.

RemoteAddr

• The client IP address that matches the request. To be more precise, it is the IP address of the last network proxy. You can have multiple IP addresses, separated by commas.

Host

• Matches the value of the host part in the Host request header (excluding the port). Multiple values ​​are allowed, separated by commas. Ant can match
• AntPathMatcher is used for matching, and the path separator is "."

Cookie

• Matches the name and value of a cookie. The value can be a regular expression.

Weight

• Used for load balancing of different routes. Routes in the same group are loaded according to weights.
• You can configure 2 values, separated by commas, which are grouping and weight.
• WeightCalculatorWebFilter: When started, a two-layer Map is generated according to the Weight configuration. The first layer is the group name and the second layer is the routing ID. When a request comes, a random number of 0~1 is generated, and a routing ID is selected for each group.
• WeightRoutePredicateFactory: When filtering by predicate, filter by group and route ID

filter

• The configuration is written in the same way as the predicate. The string is written as follows: the first part corresponds to the GatewayFilterFactory class name prefix, and the second part is the parameter.
• Filters are used to modify requests and responses

AddRequestHeader

• Add a request header, the backend can get
• The request header value can be dynamically obtained from uriVariables

StripPrefix

• There is only one integer value n. Split the requested path by "/" and remove the prefix n.

Limiting

Cross-domain

spring.cloud.gateway.globalcors:
  cors-configurations:
    '[/**]': #跨域的uriPattern
      allowedHeaders: "*"
      allowedOrigins: "*"
      allowedMethods:
        - POST
        - OPTIONS
        - GET
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• The server determines whether it is a cross-domain request by checking whether the request header Origin is the same as the scheme, host, and port of the request URL. If any one of them is different, it is a cross-domain request.
• There must be a cross-domain configuration, and the requested URI matches the uriPattern of the cross-domain configuration. The gateway will then determine whether it is cross-domain. If it is cross-domain, the gateway will check whether the request header, source, and request method allowed for cross-domain in the cross-domain configuration match the request header, source, and request method of the actual request. If they all match, cross-domain access is performed, otherwise 403Forbidden is returned
• org.springframework.web.reactive.handler.AbstractHandlerMapping#getHandler
• org.springframework.web.cors.reactive.DefaultCorsProcessor#process

Automatically generate routes

• Supports obtaining service IDs through service discovery, and automatically generates routing configurations based on service IDs. The default routing configuration uri is lb://serviceId, the predicate is /serviceId/**, and the filter is Rewritepath to remove serviceId

Global Filters

ReactiveLoadBalancerClientFilter

• To process the route URI with lb scheme, first obtain the service instance according to the service name through ServiceInstanceListSupplier, and then load balance it through ReactorLoadBalancer instance

RouteToRequestUrlFilter

• Do two things: 1. Support two-layer scheme, save the outer scheme to GATEWAY_SCHEME_PREFIX_ATTR, and then remove it. 2. Use the inner sheme, host, and port to replace the actual requested uri to achieve forwarding