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2.3 Eureka Server的REST API简介

前面已经介绍了一个最基本的Eureka Server及Eureka Client，它是整个Spring Cloud生态里面“服务注册及发现”的一个缩影。这里举的是使用Java语言的Client端的例子，但是实际Eureka Server提供了REST API，允许非Java语言的其他应用服务通过HTTP REST的方式接入Eureka的服务发现中。本节主要介绍下Eureka Server的REST API的基本操作。

2.3.1 REST API列表

Eureka在GitHub的wiki上专门写了一篇《Eureka REST operations》来介绍Eureka Server的REST API接口，Spring Cloud Netflix Eureka跟Spring Boot适配之后，提供的REST API与原始的REST API有一点点不同，其路径中的{version}值固定为eureka，其他的变化不大，如表2-2所示。

表2-2 Eureka REST API接口列表

2.3.2 REST API实例

1．查询所有应用实例

        HTTP/1.1200
        Content-Type: application/xml
        Transfer-Encoding: chunked

    Date: Tue, 19 Jun 2018 06:22:56 GMT
    <applications>
        <versions__delta>1</versions__delta>
        <apps__hashcode>UP_1_</apps__hashcode>
        <application>
            <name>DEMO-CLIENT1</name>
            <instance>
                <instanceId>10.2.238.223:demo-client1:8081</instanceId>
                <hostName>10.2.238.223</hostName>
                <app>DEMO-CLIENT1</app>
                <ipAddr>10.2.238.223</ipAddr>
                <status>UP</status>
                <overriddenstatus>UNKNOWN</overriddenstatus>
                <port enabled="true">8081</port>
                <securePort enabled="false">443</securePort>
                <countryId>1</countryId>
                <dataCenterInfo  class="com.netflix.appinfo.InstanceInfo$DefaultDataC
                    enterInfo">
                    <name>MyOwn</name>
                </dataCenterInfo>
                <leaseInfo>
                    <renewalIntervalInSecs>30</renewalIntervalInSecs>
                    <durationInSecs>90</durationInSecs>
                    <registrationTimestamp>1529377552795</registrationTimestamp>
            <lastRenewalTimestamp>1529389437739</lastRenewalTimestamp>
                    <evictionTimestamp>0</evictionTimestamp>
                    <serviceUpTimestamp>1529377552795</serviceUpTimestamp>
                </leaseInfo>
                <metadata>
                    <management.port>8081</management.port>
                </metadata>
                <homePageUrl>http://10.2.238.223:8081/</homePageUrl>
    <statusPageUrl>http://10.2.238.223:8081/actuator/info</statusPageUrl>
    <healthCheckUrl>http://10.2.238.223:8081/actuator/health</healthCheckUrl>
                <vipAddress>demo-client1</vipAddress>
                <secureVipAddress>demo-client1</secureVipAddress>
    <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
                <lastUpdatedTimestamp>1529377552795</lastUpdatedTimestamp>
                <lastDirtyTimestamp>1529377552665</lastDirtyTimestamp>
                <actionType>ADDED</actionType>
            </instance>
        </application>
    </applications>

2．根据appId查询

    curl -i http://localhost:8761/eureka/apps/demo-client1
    HTTP/1.1200
    Content-Type: application/xml

    Transfer-Encoding: chunked
    Date: Tue, 19 Jun 2018 06:28:34 GMT
    <application>
        <name>DEMO-CLIENT1</name>
        <instance>
            <instanceId>10.2.238.223:demo-client1:8081</instanceId>
            <hostName>10.2.238.223</hostName>
            <app>DEMO-CLIENT1</app>
            <ipAddr>10.2.238.223</ipAddr>
            <status>UP</status>
            <overriddenstatus>UNKNOWN</overriddenstatus>
            <port enabled="true">8081</port>
            <securePort enabled="false">443</securePort>
            <countryId>1</countryId>
            <dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
                <name>MyOwn</name>
            </dataCenterInfo>
            <leaseInfo>
                <renewalIntervalInSecs>30</renewalIntervalInSecs>
                <durationInSecs>90</durationInSecs>
                <registrationTimestamp>1529377552795</registrationTimestamp>
                <lastRenewalTimestamp>1529389797866</lastRenewalTimestamp>
                <evictionTimestamp>0</evictionTimestamp>
                <serviceUpTimestamp>1529377552795</serviceUpTimestamp>
            </leaseInfo>
            <metadata>
                <management.port>8081</management.port>
            </metadata>
            <homePageUrl>http://10.2.238.223:8081/</homePageUrl>
            <statusPageUrl>http://10.2.238.223:8081/actuator/info</statusPageUrl>
            <healthCheckUrl>http://10.2.238.223:8081/actuator/health</healthCheckUrl>
            <vipAddress>demo-client1</vipAddress>
            <secureVipAddress>demo-client1</secureVipAddress>
            <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
            <lastUpdatedTimestamp>1529377552795</lastUpdatedTimestamp>
            <lastDirtyTimestamp>1529377552665</lastDirtyTimestamp>
            <actionType>ADDED</actionType>
        </instance>
    </application>

查询不到则返回如下结果：

    curl -i http://localhost:8761/eureka/apps/demo
    HTTP/1.1404
    Content-Type: application/xml
    Content-Length: 0
    Date: Tue, 19 Jun 2018 06:38:14 GMT

3．根据appId及instanceId查询

查询出数据时跟上面的返回一致，查找不到则返回如下结果：

    curl -i http://localhost:8761/eureka/apps/demo-client1/notfound
    HTTP/1.1404

    Content-Type: application/xml
    Content-Length: 0
    Date: Tue, 19 Jun 2018 06:33:42 GMT

4．根据instanceId查询

    curl -i http://localhost:8761/eureka/instances/10.2.238.223:demo-client1:8081
    HTTP/1.1200
    Content-Type: application/xml
    Transfer-Encoding: chunked
    Date: Tue, 19 Jun 2018 06:36:09 GMT
    <instance>
        <instanceId>10.2.238.223:demo-client1:8081</instanceId>
        <hostName>10.2.238.223</hostName>
        <app>DEMO-CLIENT1</app>
        <ipAddr>10.2.238.223</ipAddr>
        <status>UP</status>
        <overriddenstatus>UNKNOWN</overriddenstatus>
        <port enabled="true">8081</port>
        <securePort enabled="false">443</securePort>
        <countryId>1</countryId>
        <dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
            <name>MyOwn</name>
        </dataCenterInfo>
        <leaseInfo>
            <renewalIntervalInSecs>30</renewalIntervalInSecs>
            <durationInSecs>90</durationInSecs>
            <registrationTimestamp>1529377552795</registrationTimestamp>
            <lastRenewalTimestamp>1529390248015</lastRenewalTimestamp>
            <evictionTimestamp>0</evictionTimestamp>
            <serviceUpTimestamp>1529377552795</serviceUpTimestamp>
        </leaseInfo>
        <metadata>
            <management.port>8081</management.port>
        </metadata>
        <homePageUrl>http://10.2.238.223:8081/</homePageUrl>
        <statusPageUrl>http://10.2.238.223:8081/actuator/info</statusPageUrl>
    <healthCheckUrl>http://10.2.238.223:8081/actuator/health</healthCheckUrl>
        <vipAddress>demo-client1</vipAddress>
        <secureVipAddress>demo-client1</secureVipAddress>
        <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
        <lastUpdatedTimestamp>1529377552795</lastUpdatedTimestamp>
        <lastDirtyTimestamp>1529377552665</lastDirtyTimestamp>
        <actionType>ADDED</actionType>
    </instance>

查询不到则返回如下结果：

    curl -i http://localhost:8761/eureka/instances/demo-instance-id
    HTTP/1.1404
    Content-Type: application/xml
    Content-Length: 0
    Date: Tue, 19 Jun 2018 06:36:51 GMT

5．注册新应用实例

xml格式提交的实例如下：

    curl -i -H "Content-Type: application/xml" -H "Content-Length: 773" -H "Accept-
        Encoding: gzip" -X POST -d '<instance>
        <instanceId>client2:8082</instanceId>
        <hostName>127.0.0.1</hostName>
        <app>CLIENT2</app>
        <ipAddr>127.0.0.1</ipAddr>
        <status>UP</status>
        <overriddenstatus>UNKNOWN</overriddenstatus>
        <port enabled="true">8082</port>
        <securePort enabled="false">7002</securePort>
        <countryId>1</countryId>
        <dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
            <name>MyOwn</name>
        </dataCenterInfo>
        <metadata class="java.util.Collections$EmptyMap"/>
        <vipAddress>client2</vipAddress>
        <secureVipAddress>client2</secureVipAddress>
        <isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
        <lastUpdatedTimestamp>1529397327986</lastUpdatedTimestamp>
        <lastDirtyTimestamp>1529397327986</lastDirtyTimestamp>
    </instance>' http://localhost:8761/eureka/apps/client2
    HTTP/1.1204
    Content-Type: application/xml
    Date: Tue, 19 Jun 2018 08:35:59 GMT

json格式提交的实例如下：

    curl -i -H "Content-Type: application/json" -X POST -d '{
        "instance": {
            "instanceId": "client2:8082",
            "app": "client2",
            "appGroupName": null,
            "ipAddr": "127.0.0.1",
            "sid": "na",
            "homePageUrl": null,
            "statusPageUrl": null,
            "healthCheckUrl": null,
            "secureHealthCheckUrl": null,
            "vipAddress": "client2",
            "secureVipAddress": "client2",
            "countryId": 1,
            "dataCenterInfo": {
                "@class": "com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo",
                "name": "MyOwn"
            },
            "hostName": "127.0.0.1",
            "status": "UP",
            "leaseInfo": null,
            "isCoordinatingDiscoveryServer": false,
            "lastUpdatedTimestamp": 1529391461000,
            "lastDirtyTimestamp": 1529391461000,
            "actionType": null,

            "asgName": null,
            "overridden_status": "UNKNOWN",
            "port": {
                "$": 8082,
                "@enabled": "true"
            },
            "securePort": {
                "$": 7002,
                "@enabled": "false"
            },
            "metadata": {
                "@class": "java.util.Collections$EmptyMap"
            }
        }
    }' http://localhost:8761/eureka/apps/client2
    HTTP/1.1204
    Content-Type: application/xml
    Date: Tue, 19 Jun 2018 06:58:18 GMT

6．注销应用实例

    curl -i -X DELETE http://localhost:8761/eureka/apps/client2/client2:8082
    HTTP/1.1200
    Content-Type: application/xml
    Content-Length: 0
    Date: Tue, 19 Jun 2018 06:59:31 GMT

7．暂停/下线应用实例

成功则返回：

    curl -i -X PUT http://localhost:8761/eureka/apps/demo-client1/10.2.238.223:demo-
        client1:8081/status\? value\=OUT_OF_SERVICE
    HTTP/1.1200
    Content-Type: application/xml
    Content-Length: 0
    Date: Tue, 19 Jun 2018 07:12:24 GMT

此时Eureka界面示例如图2-3所示。

图2-3 下线服务时Eureka界面展示示例

找不到该实例返回：

        curl -i -X PUT http://localhost:8761/eureka/apps/demo-client1/10.2.238.223:demo-
            client1:8081/status\? value\=OUT_OF_SERVICE
        HTTP/1.1404
        Content-Type: application/xml
        Content-Length: 0
        Date: Tue, 19 Jun 2018 07:11:17 GMT

8．恢复应用实例

        curl -i -X DELETE http://localhost:8761/eureka/apps/demo-client1/10.2.238.223:demo-
            client1:8081/status
        HTTP/1.1200
        Content-Type: application/xml
        Content-Length: 0
        Date: Tue, 19 Jun 2018 07:14:03 GMT

9．应用实例发送心跳

        curl -i -X PUT http://localhost:8761/eureka/apps/demo-client1/10.2.238.223:demo-
            client1:8081
        HTTP/1.1200
        Content-Type: application/xml
        Content-Length: 0
        Date: Tue, 19 Jun 2018 07:16:38 GMT

10．修改应用实例元数据

        curl -i -X PUT http://localhost:8761/eureka/apps/demo-client1/10.2.238.223:demo-
            client1:8081/metadata\? profile\=canary
        HTTP/1.1200
        Content-Type: application/xml
        Content-Length: 0
        Date: Tue, 19 Jun 2018 07:18:18 GMT

设置metadata，其中key为proflie, value为canary。

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