How to get backup hmaster in Hbase HA mode in ambari using command

[#1]

Hi, guys, I am tryign to write a autotest shell script killing the hmasters in HA mode, do you know how can I get the backup hmaster host address by using the command? I can manully find it in the ambari UI, but can not locate it by using the command

[#2]

@Qinglin Xia

You can use the Ambari APIs to find that out using simple "curl" GET you should be able to find the Active HBase Master:

http://erie1.example.com:8080/api/v1/clusters/ErieCluster/components/HBASE_MASTER?ServiceComponentIn...

Example Output:

{
  "href" : "http://erie1.example.com:8080/api/v1/clusters/ErieCluster/components/HBASE_MASTER?ServiceComponentInfo/category=MASTER&fields=ServiceComponentInfo/service_name,host_components/HostRoles/display_name,host_components/metrics/hbase/master/IsActiveMaster",
  "ServiceComponentInfo" : {
    "category" : "MASTER",
    "cluster_name" : "ErieCluster",
    "component_name" : "HBASE_MASTER",
    "service_name" : "HBASE"
  },
  "host_components" : [
    {
      "href" : "http://erie1.example.com:8080/api/v1/clusters/ErieCluster/hosts/erie3.example.com/host_components/HBASE_MASTER",
      "HostRoles" : {
        "cluster_name" : "ErieCluster",
        "component_name" : "HBASE_MASTER",
        "display_name" : "HBase Master",
        "host_name" : "erie3.example.com"
      },
      "metrics" : {
        "hbase" : {
          "master" : {
            "IsActiveMaster" : "false"
          }
        }
      }
    },
    {
      "href" : "http://erie1.example.com:8080/api/v1/clusters/ErieCluster/hosts/erie4.example.com/host_components/HBASE_MASTER",
      "HostRoles" : {
        "cluster_name" : "ErieCluster",
        "component_name" : "HBASE_MASTER",
        "display_name" : "HBase Master",
        "host_name" : "erie4.example.com"
      },
      "metrics" : {
        "hbase" : {
          "master" : {
            "IsActiveMaster" : "true"
          }
        }
      }
    }
  ]
}

Notice:

 "IsActiveMaster" : "false"

.

[#3]

@Qinglin Xia

More easy command to access this info using curl by hitting the URL:

http://erie1.example.com:8080/api/v1/clusters/ErieCluster/hosts/erie3.example.com/host_components/HB...

 curl -u admin:admin -H "X-Requested-By: ambari"  -X GET http://erie1.example.com:8080/api/v1/clusters/ErieCluster/hosts/erie4.example.com/host_components/HB...


{
  "href" : "http://erie1.example.com:8080/api/v1/clusters/ErieCluster/hosts/erie4.example.com/host_components/HBASE_MASTER?fields=metrics/hbase/master/IsActiveMaster",
  "HostRoles" : {
    "cluster_name" : "ErieCluster",
    "component_name" : "HBASE_MASTER",
    "host_name" : "erie4.example.com"
  },
  "host" : {
    "href" : "http://erie1.example.com:8080/api/v1/clusters/ErieCluster/hosts/erie4.example.com"
  },
  "metrics" : {
    "hbase" : {
      "master" : {
        "IsActiveMaster" : "true"
      }
    }
  }
}

.

[#4]

You should also be able to specify the condition IsActiveMaster=false to have the API respond with non-active HBaseMasters only. Instead of saying "fields=metrics/hbase/master/IsActiveMaster" in the query, you can turn that into a predicate by saying "metrics/hbase/master/IsActiveMaster=false".

[#5 · Accepted solution]

@Qinglin Xia

This can be achieved with single Ambari REST API as @yusaku suggested. Following is the actual working API

{
  "href" : "http://c6401.ambari.apache.org:8080/api/v1/clusters/c1/components/HBASE_MASTER?host_components/metrics/hbase/master/IsActiveMaster=true&fields=host_components/HostRoles/host_name",
  "ServiceComponentInfo" : {
    "cluster_name" : "c1",
    "component_name" : "HBASE_MASTER",
    "service_name" : "HBASE"
  },
  "host_components" : [
    {
      "href" : "http://c6401.ambari.apache.org:8080/api/v1/clusters/c1/hosts/c6401.ambari.apache.org/host_components/HBASE_MASTER",
      "HostRoles" : {
        "cluster_name" : "c1",
        "component_name" : "HBASE_MASTER",
        "host_name" : "c6401.ambari.apache.org"
      },
      "metrics" : {
        "hbase" : {
          "master" : {
            "IsActiveMaster" : "true"
          }
        }
      }
    }
  ]
}

[#6]

Thanks, I used this url to get the backup masters

http://fsmanager:8080/api/v1/clusters/${cluster_name}/components/HBASE_MASTER?host_components/metric...

[#7]

@Qinglin Xia

Additionally if you due to some reason if the Ambari is down (not accessible) and still if you want to get the Active HBase Master detail then you can simply use the HBase JMX for the same. Here "16010" is HBase JMX ui port.

Exampe:

$ curl -v --silent 'http://erie4.example.com:16010/jmx?qry=Hadoop:service=HBase,name=Master,sub=Server'  2>&1 | grep isActiveMaster
    "tag.isActiveMaster" : "true",


$ curl -v --silent 'http://erie3.example.com:16010/jmx?qry=Hadoop:service=HBase,name=Master,sub=Server'  2>&1 | grep isActiveMaster
    "tag.isActiveMaster" : "false",