Microservice API gateway zuul

1. Why

Why micro services need API gateway , Because in the microservice Architecture , Back end services are often not directly open to client , But through a API gateway On request url,
route To the corresponding service . When adding API After gateway , A wall is created between third-party clients and back-end services , This wall directly communicates with the caller for permission control , Then distribute the request evenly to the background server .Spring Cloud Provides a solution : zuul gateway .

API gateway It provides a unified access to services in the microservice architecture , Client pass API Gateway access related services .API The definition of gateway is similar to Facade mode , It is equivalent to the facade of the whole microservice architecture , All client access is routed and filtered through it . It has achieved Request routing 、 Load balancing 、 Check filter 、 Service fault tolerance 、 Service aggregation and other functions .

2. Zuul

2.1 brief introduction

Zuul Routing is an integral part of microservice architecture , Provide dynamic routing , monitor , elastic , Edge services for security, etc .
Zuul yes Netflix One of the products is based on JVM Load balancer on Routing and server side ( Microservice gateway ).
The main functions are agent , Dynamic routing , filter etc. .
Zuul Of GitHub Open source →
Official website information →
Zuul You can talk to Eureka, Ribbon, Hystrix And other components . Use Eureka Gateway microservice architecture for service registration and discovery :

2.2 zuul What can I do?

route , Filter , Load balancing , Gray scale release, etc .

Grayscale Publishing , Also known as Canary release .
The origin is , The miners found that , Canaries are very sensitive to gas , The miner will go down the well before , Put a canary in the well first , Such as
The Canary stopped barking , It means high gas concentration .

After gray scale publishing begins , Start a new version of the app first , But it doesn't cut the flow directly , It's the testers who make progress in the new version
Online test , Start this new version of the app , It's our canary . If there is no problem , Then a small number of user flows
Import quantity to the new version , And then observe the running state of the new version , Collect all kinds of runtime data , If you make changes to the old and new versions at this time
Comparison of various data , It's called A/B test . There's nothing wrong with the new version , Then gradually expand the scope 、 Traffic , Move all users
Move to the new version .

route The function is responsible for forwarding external requests to specific service instances , It's the foundation of unified access portal .

3. Zuul Gateway microservice practice

Create gateway microservices [microservicecloud-zuul-gateway]

3.1 Import dependence

Import zuul and eureka client Dependence （ The gateway service itself needs to be registered to Eureka）

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-netflix-zuul</artifactId>
</dependency>

3.2 The startup class starts the agent configuration

Startup class add @EnableZuulProxy annotation , Open the gateway proxy configuration .

/** * zuul  Gateway startup class  */
@SpringBootApplication
@EnableEurekaClient
@EnableZuulProxy //  Turn on Zuul Proxy configuration 
public class ZuulGatewayApplication {
    
    public static void main(String[] args) {
    
        SpringApplication.run(ZuulGatewayApplication.class, args);
    }
}

3.3 Write the configuration

application.yml Add registration to the file eureka Configuration of .

server:
  port: 10010
spring:
  application:
    name: zuul-gateway
## Eureka Client configuration 
eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone: http://www.eureka01.com:7001/eureka,http://www.eureka02.com:7002/eureka,http://www.eureka03.com:7003/eureka
  instance:
    prefer-ip-address: true
    instance-id: zuul-gateway-01

3.4 Configure routing rules

application.yml Configure routing rules in the file , There are several ways to configure routing rules . The following are listed respectively .

3.4.1 Mode one

## zuul Routing configuration 
##  Route mapping configuration 1,  It is also the default configuration 
zuul:
  routes:
    microservicecloud-provider:
      path: /microservicecloud-provider
      serviceId: microservicecloud-provider
    microservicecloud-consumer:
      path: /microservicecloud-consumer
      serviceId: microservicecloud-consumer

Tips :
Forwarding path path And the name of the routed microservice instance serviceId Consistent time , It can be omitted completely zuul Dynamic routing configuration . That is, the above is the default configuration .
Only the mapping rules that appear in the configuration file will be created , And from Eureka Other services obtained in ,zuul Routing rules will not be created for them .

After starting the gateway microservice , We no longer visit directly The back-end service 了 , But through Gateway microservice Route and forward . Here are the test results of the default routing configuration .

3.4.2 Mode two

The default routing configuration rules are used in practical application scenarios , There are also problems . The instance name of the backend microservice is exposed in url in , There may be security risks . Let's customize path The way , The requested url Use in Alias , Again by Zuul gateway Route and forward to the back-end specific service provider .

##  Route mapping configuration 2,  Hide the microservice name , Use alias path 
zuul:
  routes:
    myprovider:
      path: /myprovider/**
      serviceId: microservicecloud-provider
    myconsumer:
      path: /myconsumer/**
      serviceId: microservicecloud-consumer

Or simplify it

##  Route mapping configuration 2,  Hide the microservice name , Use alias path 
zuul:
  routes:
    myprovider.path: /myprovider/**
    myprovider.serviceId: microservicecloud-provider

    myconsumer.path: /myconsumer/**
    myconsumer.serviceId: microservicecloud-consumer

The routing mapping configuration uses custom path after , The original default route mapping rules are also effective , You can still request in the above way . In order not to expose the back-end service instance name , We use custom path Of url request , Here are the test results .

3.4.3 Mode three

Use simpler zuul.routes.<serviceId>=<path> Configuration mode , The usage and test effect are the same as above .

zuul.routes.microservicecloud-provider=/myprovider/**
zuul.routes.microservicecloud-consumer=/consumer/**

##  Route mapping configuration 3,  Simplified edition 
zuul:
  routes:
    microservicecloud-provider: /myprovider/**
    microservicecloud-consumer: /consumer/**

3.5 Zuul Gateway configuration supplement

API gateway In the use of , You can also filter out micro service instances or... That do not want to use gateway routing rules through configuration items path. For example, sometimes ,
There are some services that we don't need to open to the outside world and are also accessed by the outside . We can use it at this time zuul.ignore-services Parameter to set a service name matching expression to define Rules that do not automatically create routes .zuul When automatically creating a service route, it will be judged according to the expression , If the service name matches the expression , that zuul The service will be skipped , Do not create routing rules for it .
such as , Set to zuul.ignored-services='*',zuul Routing rules will not be automatically created for all services .

Configure ignore service

zuul:
 #  Some routing configurations are omitted here ...
  ignored-services: microservicecloud-api #  Ignored microservice instances ; '*'  Indicates that all micro service routes are ignored 
  ignored-patterns: /**/hello/** #  Neglected path

The above configuration is microservicecloud-api Ignore ( Do not create routing rules ), The route of the service instance is filtered .
that http://localhost:port/microservicecloud-api/**/** Of url Requests will not be routed , The request failed .

You can also give the request gateway url Add Prefix Support .

zuul:
	#  Some routing configurations are omitted here ...
    prefix: /gatewayto #  Prefix of gateway access 

To configure Prefix Test effect of access .

3.6 Zuul Gateway load balancing

because Zuul Automatic integration Ribbon and Hystrix, therefore Zuul Born with Load balancing and service fault tolerance .

3.7 View route information

Check the indispensable endpoint access dependencies

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

Add endpoint exposure , Submit the configuration of endpoint access

#  Turn on the endpoint of view route 
management:
  endpoints:
    web:
      exposure:
        include: 'routes'

restart zuul Gateway microservice , visit http://localhost:10010/actuator/routes , You can view the routing information .

4. Zuul filter

4.1 Zuul Filter introduction

Dynamic routing function at real time , its Route mapping and Request forwarding Are made up of several different Zuul Filter finished .
Route mapping from pre type Your filter is complete , It matches the request path with the configured routing rules , To find the destination address to forward ;
Request forwarding from route type Filter to complete , Yes pre The routing address obtained by the type filter is forwarded .
therefore ,Zuul The filter can be said to be Zuul Realization API Gateway function is the most core component .

4.2 Zuul filter - Method statement

(1) filterType： This function needs to return a string to represent the type of filter , And this type is in HTTP The stages defined in the request process . stay Zuul in
By default, four filter types with different lifecycles are defined , As follows ：

• pre： Execute before the request is routed to the target service , For example, authority verification 、 Print log and other functions ;
• route： Execute... When the request is routed to the target service .
• post： Execute... After the request is routed to the target service , For example, add header information to the response of the target service , Collect statistics and other functions ;
• error： Requests are executed when errors occur in other stages .

(2) filterOrder： adopt int Value to define the order in which filters are executed , The smaller the value, the higher the priority .

(3) shouldFilter： Return to one boolean Type to determine whether the filter is to be executed . We can use this method to specify the effective range of the filter .

(4) run： The specific logic of the filter . In this function , We can implement custom filtering logic , To determine whether to intercept the current request , Do not follow up > route , Or after the request route returns the result , Do some processing for the processing results, etc .

4.3 Zuul filter - Life cycle

Normal process :

Request arrives first pre filter Mapping request paths to routing rules , Then arrive routing filter Route and forward , The request reaches the real service provider , Perform the requested , Return results , Will arrive post filter after , Complete the response .

Abnormal flow :

• The whole process , pre perhaps routing filter Something unusual happened , They'll go straight in error filter , stay error filter After processing , Will give the request to post filter , Last return to user .
• If it is error filter Something unusual happened to me , Eventually, it will enter post filter , And then back to the user .
• If it is post filter Something unusual happened , Will jump to error filter , But with the pre and routing filter The difference is , The request will not arrive again post filter , Instead, it is returned directly to the user .

4.4 To write Zuul filter

Zuul The filter of gateway can also do Permission to check exception handling And so on .
Step blog : Explain profound theories in simple language SpringCloud→ chapter 6.5.4 To write Zuul filter

5. Personal blog

Welcome to personal blog : https://www.crystalblog.xyz/

Alternate address : https://wang-qz.gitee.io/crystal-blog/