spring-cloud-eureka-server

Run a standalone demo at local

Step 1. Bind hosts
Edit /etc/hosts, add following content:

127.0.0.1 standalone.eureka
127.0.0.1 eureka-peer1
127.0.0.1 eureka-peer2
127.0.0.1 eureka-peer3

Step 2. Create a docker network

docker network create --driver=bridge --ipv6 --ipam-driver=default --subnet=172.16.238.0/24 --subnet=2001:3984:3989::/64 local-network

docker network create --driver=bridge --ipam-driver=default --subnet=172.16.238.0/24 local-network

Step 3. docker-compose up or

# OSX way to get HOST_IPADDRESS
HOST_IPADDRESS=$(ipconfig getifaddr en0 || ipconfig getifaddr en1) \
docker-compose -f docker-compose-local-cluster.yml up

Homepage http://standalone.eureka:8761

Access http://standalone.eureka:8761/eureka/apps to get application infos.

Instance Status in Eureka and Overridden Status

Eureka defined 5 status. + UP

Ready to receive traffic + DOWN Do not send traffic- healthcheck callback failed + STARTING Just about starting- initializations to be done - do not send traffic + OUT_OF_SERVICE Intentionally shutdown for traffic + UNKNOWN

Overridden Status is for black/red deployment.

1. Set overridden status to OUT_OF_SERVICE on part of existing service instances

Take some old instances down:

curl -i -X PUT http://standalone.eureka:8761/eureka/apps/<application>/<instance-id>/status?value=OUT_OF_SERVICE

1. Start up new instances

2. If deployment failed (Found new instances malfunction), take new instances down, and take back old instances.

Delete overridden status

curl -i -X DELETE http://standalone.eureka:8761/eureka/apps/<application>/<instance-id>/status

For example, we have an application named config-server which has multiple instances.
Their instance ids are:

• config-server:config-server:8888
• config-server-2:config-server:9999

To take config-server:config-server:8888 down, run

curl -i -X PUT http://standalone.eureka:8761/eureka/apps/config-server/config-server:config-server:8888/status?value=OUT_OF_SERVICE

To take config-server:config-server:8888 back, run

curl -i -X DELETE http://standalone.eureka:8761/eureka/apps/config-server/config-server:config-server:8888/status

You can also set status directly on instances by posting request to its ServiceRegistryEndpoint
URL of ServiceRegistryEndpoint is: http(s)://<host>:<port>[server.context-path][management.context-path]/service-registry/instance-status
server.context-path and management.context-path are optional, that depends on instance’s config.

/service-registry/instance-status is a sensitive endpoint, may need to authentication (depends on instance’s config).

For example, we can set instance config-server:8888 of application config-server to OUT_OF_SERVICE by running:

curl -i -X POST -u admin:admin_pass -H 'Content-Type: application/json' -d 'OUT_OF_SERVICE' http://config-server:8888/manage/service-registry/instance-status

Note: only OUT_OF_SERVICE and UP are acceptable for this endpoint.

And then we can verify that by

curl -i -X GET -u admin:admin_pass -H 'Accept: application/json' http://config-server:8888/manage/service-registry/instance-status

We got eureka: {overriddenStatus=UNKNOWN, status=UP},consul: OUT_OF_SERVICE.
Here may be a bug that eureka’s overriddenStatus is not set correctly.
But this is ok, if you run curl -i -s -X GET http://standalone.eureka:8761/eureka/apps/config-server/config-server:config-server:8888 | grep overriddenstatus, you can see the overriddenStatus on eureka side is updated.