1. Introduction
Eureka cluster provides partition function. The design concept of this function comes from the two basic concepts of region and zone created by Amazon cloud AWS:
- Region: region refers to different regions in the physical sense. During service deployment, multiple computer rooms will be built and services will be deployed in areas with high user demand, which can reduce the problems caused by network instability
- Zone: a region can be divided into multiple zones. In other words, multiple computer room servers in a region are divided into different available zones according to certain rules (for example, if there are three computer rooms in a region, the three computer rooms can be divided into three zones). By dividing zones, the effect of disaster recovery can be achieved. If one zone fails, other zones can still provide services.
According to the above two concepts, when Eureka Server is deployed in different regions, we can use the partition function provided by Eureka cluster. This can ensure that the services registered in a zone in a region are called prior to those registered in another zone. When the current one is unavailable, select the services registered in other zones to initiate the call. This can ensure that the delay of service call is reduced.
Relationship diagram of Region and Zone:
2. Cluster deployment
2.1 resource list
Four Eureka Server services are set up this time, and the resource list is as follows:
| application-name | zone | instance-hostname | prot |
|---|---|---|---|
| Eureka-Ynatian | zone-yantian | eureka18881.com | 18881 |
| Eureka-Luohu | zone-luohu | eureka18882.com | 18882 |
| Eureka-Nanshan | zone-yantian | eureka18883.com | 18883 |
| Eureka-Baoan | zone-baoan | eureka18884.com | 18884 |
Eureka Server Cluster (Region Shenzhen, zone Luohu, zone Yantian, zone Nanshan, zone Bao'an):
The Eureka Server Cluster built here is a single Region, including four zones. If the company needs Eureka servers with high availability requirements, multiple Eureka Server servers can be deployed in each zone of the Region. If you need to make a sub Region, you can configure multiple regions by referring to Region Shenzhen.
2.2 configuration file
Eureka Server configuration file for Eureka ynati
server: port: 18881 spring: application: name: Eureka-Ynatian eureka: instance: hostname: eureka18881.com client: prefer-same-zone-eureka: true register-with-eureka: true region: shenzhen availability-zones: shenzhen: zone-yantian,zone-luohu,zone-nanshan,zone-baoan fetch-registry: true service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/
Eureka Server profile for Eureka Luohu
server: port: 18882 spring: application: name: Eureka-Luohu eureka: instance: hostname: eureka18882.com client: prefer-same-zone-eureka: true register-with-eureka: true region: shenzhen availability-zones: shenzhen: zone-luohu,zone-yantian,zone-nanshan,zone-baoan fetch-registry: true service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/
Eureka Nanshan's Eureka Server profile
server: port: 18883 spring: application: name: Eureka-Nanshan eureka: instance: hostname: eureka18883.com client: prefer-same-zone-eureka: true register-with-eureka: true region: shenzhen availability-zones: shenzhen: zone-nanshan,zone-luohu,zone-yantian,zone-baoan fetch-registry: true service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/
Eureka Server profile for Eureka Baoan
server: port: 18884 spring: application: name: Eureka-Baoan eureka: instance: hostname: eureka18884.com client: prefer-same-zone-eureka: true register-with-eureka: true region: shenzhen availability-zones: shenzhen: zone-baoan,zone-nanshan,zone-luohu,zone-yantian fetch-registry: true service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/
2.3 start the cluster
Start the four Eureka Server services in the cluster in turn. After the clusters stabilize, access the Eureka Server Dashboard. At this time, you can see the same service registration information Instance currently registered with Eureka and DS Replicaes information in any of the four Eureka servers (this is different, you don't need to replicate yourself...), This indicates that Eureka Server Cluster has started normally.
2.4 service registration
In addition to achieving high availability, Eureka Server partition is mainly to provide optimal services to clients, so as to achieve the fastest response of services. Register two services Server-01 and Server-02 in Eureka Server. Select zone Yantian for the metadata map zone in Server-01 and zone Louhu for the metadata map zone in Server-02. (note that the service name of both services is Server)
Server-01 profile
server: port: 19991 spring: application: name: Server eureka: instance: prefer-ip-address: true metadata-map: zone: zone-yantian client: region: shenzhen availability-zones: shenzhen: zone-yantian,zone-luohu,zone-nanshan,zone-baoan service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/ fetch-registry: true register-with-eureka: true prefer-same-zone-eureka: true
A Rest Api endpoint is provided in Server-01
@RestController
@RequestMapping("/zone")
public class ZoneController {
@GetMapping
public String zone() {
return "Server zone-yantian";
}
}
Server-02 profile
server: port: 19992 spring: application: name: Server eureka: instance: prefer-ip-address: true metadata-map: zone: zone-luohu client: region: shenzhen availability-zones: shenzhen: zone-luohu,zone-yantian,zone-nanshan,zone-baoan service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/ fetch-registry: true register-with-eureka: true prefer-same-zone-eureka: true
A Rest Api endpoint is provided in Server-02
@RestController
@RequestMapping("/zone")
public class ZoneController {
@GetMapping
public String zone() {
return "Server zone-luohu";
}
}
At this point, visit Eureka dashboard and you can see that two instances of Eureka Server are registered in Eureka Server Cluster.
2.4 service consumption
Create a service consumer Consumer-01 to test the specific situation of service call distribution.
Consumer-01 configuration file, where metadata-map.zone is specified as zone Luohu
server: port: 17771 spring: application: name: Consumer-01 eureka: instance: prefer-ip-address: true metadata-map: zone: zone-luohu client: region: shenzhen availability-zones: shenzhen: zone-luohu,zone-yantian,zone-nanshan,zone-baoan service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/ fetch-registry: true register-with-eureka: true prefer-same-zone-eureka: true
Provide a Rest Api access endpoint:
@RestController
@RequestMapping("/consumer")
public class ZoneController {
@Autowired
private RestTemplate restTemplate;
@GetMapping
public String zone() {
return restTemplate.getForObject("http://server/zone", String.class);
}
}
When the browser accesses the endpoint, no matter how to refresh, it will output server zone Louhu, indicating that the request has been called to Server-02
Modify the configuration file of Consumer-01, and modify the metadata map: zone to zone Yantian
server: port: 17771 spring: application: name: Consumer-01 eureka: instance: prefer-ip-address: true metadata-map: zone: zone-yantian client: region: shenzhen availability-zones: shenzhen: zone-luohu,zone-yantian,zone-nanshan,zone-baoan service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/ fetch-registry: true register-with-eureka: true prefer-same-zone-eureka: true
Re visit the browser and request the endpoint provided by Consumer-01. At this time, no matter how to refresh, the server zone Yantian will be output, indicating that the request has been called to Server-01
2.5 configuration details
There are several very important configuration items in service registration and service consumption: Prefer same zone Eureka and eureka.instance.metadata-map.zone
prefer-same-zone-eureka
eureka: client: region: shenzhen availability-zones: shenzhen: zone-luohu,zone-yantian,zone-nanshan,zone-baoan service-url: zone-yantian: http://eureka18881.com:18881/eureka/ zone-luohu: http://eureka18882.com:18882/eureka/ zone-nanshan: http://eureka18883.com:18883/eureka/ zone-baoan: http://eureka18884.com:18884/eureka/
- true: get the list of zones under eureka.client.availability-zones, and select the first zone for service registration. If the first registration fails, select other zones in turn for service registration
- false: obtain the eureka.client.service-url list and select the first service URL address for service registration. If the first address registration fails, select other service URL service addresses in turn for registration
eureka.instance.metadata-map.zone
eureka: instance: metadata-map: zone: zone-yantian
The eureka.instance.metadata-map.zone configuration item is used to identify which zone the service provider and service consumer belong to. The service consumer pulls the service list from Eureka Server through the ribbon. If there are multiple services in a zone, poll the service list in each zone; If none of the services in the zone can be accessed, try to access the services in other zones.