Interacting with Eureka via it’s REST operations

In previous posts we’ve used Steeltoe to interact with Eureka. Obviously Steeltoe gives us good patterns for interacting with Eureka but also has the capability to work with other service discovery registries etc.

Steeltoe’s great, but what if we wanted to just write our own Eureka either for learning how things work or maybe we just want to write our own for .NET or for another language/technology?

Eureka exposes REST operations for everything you’ll need to do with a service registry, let’s take a look.

Note: I’ll give examples using localhost, obviously change to your Eureka host/ip and I’ll also show data based upon the weatherapi we’ve worked on previously.

Query for all applications and their instances

GET method:
```
http://localhost:8761/eureka/apps
```

Response:

<applications>
  <versions__delta>1</versions__delta>
  <apps__hashcode>UP_1_</apps__hashcode>
  <application>
    <name>WEATHERAPI</name>
    <instance>
      <instanceId>localhost:weatherapi:5001</instanceId>
      <hostName>localhost</hostName>
      <app>WEATHERAPI</app>
      <ipAddr>localhost</ipAddr>
      <status>UP</status>
      <overriddenstatus>UNKNOWN</overriddenstatus>
      <port enabled="false">8080</port>
      <securePort enabled="true">5001</securePort>
      <countryId>1</countryId>
      <dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
        <name>MyOwn</name>
      </dataCenterInfo>
      <leaseInfo>
        <renewalIntervalInSecs>30</renewalIntervalInSecs>
        <durationInSecs>90</durationInSecs>
        <registrationTimestamp>1611512017058</registrationTimestamp>
        <lastRenewalTimestamp>1611515916921</lastRenewalTimestamp>
        <evictionTimestamp>0</evictionTimestamp>
        <serviceUpTimestamp>1611512016403</serviceUpTimestamp>
      </leaseInfo>
      <metadata class="java.util.Collections$EmptyMap"/>
      <homePageUrl>https://localhost:5001/</homePageUrl>
      <statusPageUrl>https://localhost:5001/actuator/info</statusPageUrl>
      <healthCheckUrl>https://localhost:5001/actuator/health</healthCheckUrl>
      <vipAddress>weatherapi</vipAddress>
      <secureVipAddress>weatherapi</secureVipAddress>
      <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
      <lastUpdatedTimestamp>1611512017058</lastUpdatedTimestamp>
      <lastDirtyTimestamp>1611512016217</lastDirtyTimestamp>
      <actionType>ADDED</actionType>
    </instance>
  </application>
</applications>

Query for instances for a specific application id

GET method:

http://localhost:8761/eureka/apps/{your app id}

// Example
http://localhost:8761/eureka/apps/weatherapi

Response:

<application>
    <name>WEATHERAPI</name>
    <instance>
        <instanceId>localhost:weatherapi:5001</instanceId>
        <hostName>localhost</hostName>
        <app>WEATHERAPI</app>
        <ipAddr>localhost</ipAddr>
        <status>UP</status>
        <overriddenstatus>UNKNOWN</overriddenstatus>
        <port enabled="false">8080</port>
        <securePort enabled="true">5001</securePort>
        <countryId>1</countryId>
        <dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
            <name>MyOwn</name>
        </dataCenterInfo>
        <leaseInfo>
            <renewalIntervalInSecs>30</renewalIntervalInSecs>
            <durationInSecs>90</durationInSecs>
            <registrationTimestamp>1611512017058</registrationTimestamp>
            <lastRenewalTimestamp>1611516936969</lastRenewalTimestamp>
            <evictionTimestamp>0</evictionTimestamp>
            <serviceUpTimestamp>1611512016403</serviceUpTimestamp>
        </leaseInfo>
        <metadata class="java.util.Collections$EmptyMap"/>
        <homePageUrl>https://localhost:5001/</homePageUrl>
        <statusPageUrl>https://localhost:5001/actuator/info</statusPageUrl>
        <healthCheckUrl>https://localhost:5001/actuator/health</healthCheckUrl>
        <vipAddress>weatherapi</vipAddress>
        <secureVipAddress>weatherapi</secureVipAddress>
        <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
        <lastUpdatedTimestamp>1611512017058</lastUpdatedTimestamp>
        <lastDirtyTimestamp>1611512016217</lastDirtyTimestamp>
        <actionType>ADDED</actionType>
    </instance>
</application>

Query for instances by its instance id

GET method:

http://localhost:8761/eureka/apps/{your app id}/{your instance id}

// Example
http://localhost:8761/eureka/apps/weatherapi/localhost:weatherapi:5001

Response:

<instance>
    <instanceId>localhost:weatherapi:5001</instanceId>
    <hostName>localhost</hostName>
    <app>WEATHERAPI</app>
    <ipAddr>localhost</ipAddr>
    <status>UP</status>
    <overriddenstatus>UNKNOWN</overriddenstatus>
    <port enabled="false">8080</port>
    <securePort enabled="true">5001</securePort>
    <countryId>1</countryId>
    <dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
        <name>MyOwn</name>
    </dataCenterInfo>
    <leaseInfo>
        <renewalIntervalInSecs>30</renewalIntervalInSecs>
        <durationInSecs>90</durationInSecs>
        <registrationTimestamp>1611512017058</registrationTimestamp>
        <lastRenewalTimestamp>1611517116997</lastRenewalTimestamp>
        <evictionTimestamp>0</evictionTimestamp>
        <serviceUpTimestamp>1611512016403</serviceUpTimestamp>
    </leaseInfo>
    <metadata class="java.util.Collections$EmptyMap"/>
    <homePageUrl>https://localhost:5001/</homePageUrl>
    <statusPageUrl>https://localhost:5001/actuator/info</statusPageUrl>
    <healthCheckUrl>https://localhost:5001/actuator/health</healthCheckUrl>
    <vipAddress>weatherapi</vipAddress>
    <secureVipAddress>weatherapi</secureVipAddress>
    <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
    <lastUpdatedTimestamp>1611512017058</lastUpdatedTimestamp>
    <lastDirtyTimestamp>1611512016217</lastDirtyTimestamp>
    <actionType>ADDED</actionType>
</instance>

Register an application instance

POST method:
Headers: “Content-Type”: “application/json”, “Accept”: “application/json”

http://localhost:8761/eureka/apps/{your app id}

// Example
http://localhost:8761/eureka/apps/myapp

Body:

{
  "instance": {
    "hostName": "myhost",
    "app": "myapp",
    "vipAddress": "myservice",
    "secureVipAddress": "myservice",
    "ipAddr": "10.0.0.10",
    "status": "STARTING",
    "port": {"$": "8080", "@enabled": "true"},
    "securePort": {"$": "8443", "@enabled": "true"},
    "healthCheckUrl": "http://myservice:8080/healthcheck",
    "statusPageUrl": "http://myservice:8080/status",
    "homePageUrl": "http://myservice:8080",
    "dataCenterInfo": {
      "@class": "com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo", 
      "name": "MyOwn"
    }
  }
}

Response: 204 No Content

As you will see from the status we’ve set this service to STARTING and hence we need set the status to UP when our service is running. Eureka, ofcourse, is just a registry and hence you service need to updated information as required.

Delete an instance

DELETE method:

http://localhost:8761/eureka/apps/{your app id}/{your instance id}

// Example
http://localhost:8761/eureka/apps/myapp/myhost

Response: 200 OK

Send an application instance heartbeat

PUT method:

http://localhost:8761/eureka/apps/{your app id}/{your instance id}

// Example
http://localhost:8761/eureka/apps/myapp/myhost

Response: 200 OK, or 404 if the instance doesn’t exist

Take an instance out of service

PUT method:

http://localhost:8761/eureka/apps/{your app id}/{your instance id}/status?value=OUT_OF_SERVICE

// Example
http://localhost:8761/eureka/apps/myapp/myhost/status?value=OUT_OF_SERVICE

Response: 200 OK, or 500 on failure

Now in the Eureka dashboard you’ll see the large, red OUT_OF_SERVICE text.

Remove the out of service state

DELETE method:

http://localhost:8761/eureka/apps/{your app id}/{your instance id}/status?value=UP

// Example
http://localhost:8761/eureka/apps/myapp/myhost/status?value=UP

Response: 200 OK, or 500 on failure

The status UP is optional, it’s a suggestion for the status after the removal of the OUT OF SERVICE override.

Update meta data

PUT method:

http://localhost:8761/eureka/apps/{your app id}/{your instance id}/metadata?key=val

// Example
http://localhost:8761/eureka/apps/myapp/myhost/metadata?Version=2

Response: 200 OK, or 500 on failure

Query for all instance of a vip address

GET method:

http://localhost:8761/eureka/vips/{your vipAddress}

// Example
http://localhost:8761/eureka/vips/myservice

Response: 200 OK, or 404 if vipAddress does not exist

<applications>
    <versions__delta>-1</versions__delta>
    <apps__hashcode>UP_1_</apps__hashcode>
    <application>
        <name>MYAPP</name>
        <instance>
            <hostName>myhost</hostName>
            <app>MYAPP</app>
            <ipAddr>10.0.0.10</ipAddr>
            <status>UP</status>
            <overriddenstatus>UNKNOWN</overriddenstatus>
            <port enabled="true">8080</port>
            <securePort enabled="true">8443</securePort>
            <countryId>1</countryId>
            <dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
                <name>MyOwn</name>
            </dataCenterInfo>
            <leaseInfo>
                <renewalIntervalInSecs>30</renewalIntervalInSecs>
                <durationInSecs>90</durationInSecs>
                <registrationTimestamp>1611519061947</registrationTimestamp>
                <lastRenewalTimestamp>1611519061947</lastRenewalTimestamp>
                <evictionTimestamp>0</evictionTimestamp>
                <serviceUpTimestamp>1611518524498</serviceUpTimestamp>
            </leaseInfo>
            <metadata>
                <Version>2</Version>
            </metadata>
            <homePageUrl>http://myservice:8080</homePageUrl>
            <statusPageUrl>http://myservice:8080/status</statusPageUrl>
            <healthCheckUrl>http://myservice:8080/healthcheck</healthCheckUrl>
            <vipAddress>myservice</vipAddress>
            <secureVipAddress>myservice</secureVipAddress>
            <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
            <lastUpdatedTimestamp>1611519061947</lastUpdatedTimestamp>
            <lastDirtyTimestamp>1611518524498</lastDirtyTimestamp>
            <actionType>ADDED</actionType>
        </instance>
    </application>
</applications>

Query for all instance of a secure vip address

GET method:

http://localhost:8761/eureka/svips/{your svipAddress}

// Example
http://localhost:8761/eureka/svips/myservice

Response: 200 OK, or 404 is svipAddress does not exist

<applications>
    <versions__delta>-1</versions__delta>
    <apps__hashcode>UP_1_</apps__hashcode>
    <application>
        <name>MYAPP</name>
        <instance>
            <hostName>myhost</hostName>
            <app>MYAPP</app>
            <ipAddr>10.0.0.10</ipAddr>
            <status>UP</status>
            <overriddenstatus>UNKNOWN</overriddenstatus>
            <port enabled="true">8080</port>
            <securePort enabled="true">8443</securePort>
            <countryId>1</countryId>
            <dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
                <name>MyOwn</name>
            </dataCenterInfo>
            <leaseInfo>
                <renewalIntervalInSecs>30</renewalIntervalInSecs>
                <durationInSecs>90</durationInSecs>
                <registrationTimestamp>1611519061947</registrationTimestamp>
                <lastRenewalTimestamp>1611519061947</lastRenewalTimestamp>
                <evictionTimestamp>0</evictionTimestamp>
                <serviceUpTimestamp>1611518524498</serviceUpTimestamp>
            </leaseInfo>
            <metadata>
                <Version>2</Version>
            </metadata>
            <homePageUrl>http://myservice:8080</homePageUrl>
            <statusPageUrl>http://myservice:8080/status</statusPageUrl>
            <healthCheckUrl>http://myservice:8080/healthcheck</healthCheckUrl>
            <vipAddress>myservice</vipAddress>
            <secureVipAddress>myservice</secureVipAddress>
            <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
            <lastUpdatedTimestamp>1611519061947</lastUpdatedTimestamp>
            <lastDirtyTimestamp>1611518524498</lastDirtyTimestamp>
            <actionType>ADDED</actionType>
        </instance>
    </application>
</applications>

My Memory

Outsourcing my memory and thoughts (and other ramblings) to the web

Interacting with Eureka via it’s REST operations