How to retrieve the name node host name using Ambari? - ibm-cloud

Question

The python-ambariclient library has an api for retrieving the host_components:
ambari.services(service_name).components(component_name).host_components
How can I extract the name_node for an IBM Analytics Engine cluster?
I think I need to make the call:
GET https://xxxx.bi.services.us-south.bluemix.net:9443/api/v1/clusters/AnalyticsEngine/services/HDFS/components/NAMENODE?fields=host_components
Which retrieves the following information:
{
"href" : "https://xxxx.bi.services.us-south.bluemix.net:9443/api/v1/clusters/AnalyticsEngine/services/HDFS/components/NAMENODE?fields=host_components",
"ServiceComponentInfo" : {
"cluster_name" : "AnalyticsEngine",
"component_name" : "NAMENODE",
"service_name" : "HDFS"
},
"host_components" : [
{
"href" : "https://xxxx.bi.services.us-south.bluemix.net:9443/api/v1/clusters/AnalyticsEngine/hosts/xxxx.bi.services.us-south.bluemix.net/host_components/NAMENODE",
"HostRoles" : {
"cluster_name" : "AnalyticsEngine",
"component_name" : "NAMENODE",
"host_name" : "xxxx.bi.services.us-south.bluemix.net"
}
}
]
}

Answer 1

First, install the python-ambariclient library:
! pip install --quiet python-ambariclient
Next, you can use the following to retrieve the name node host name:
from future.standard_library import install_aliases
install_aliases()
from urllib.parse import urlparse
import json
vcap = json.load(open('./vcap.json'))
USER = vcap['cluster']['user']
PASSWORD = vcap['cluster']['password']
AMBARI_URL = vcap['cluster']['service_endpoints']['ambari_console']
CLUSTER_ID = vcap['cluster']['cluster_id']
url = urlparse(AMBARI_URL)
HOST = url.hostname
PORT = url.port
PROTOCOL = url.scheme
from ambariclient.client import Ambari
ambari = Ambari(HOST, port=PORT, username=USER, password=PASSWORD, protocol=PROTOCOL)
CLUSTER_NAME = ambari.clusters.next().cluster_name # gets first cluster - there will only be one
namenode_hc = ambari.clusters(CLUSTER_NAME).services('HDFS').components('NAMENODE').host_components
namenode_host_name = [hc.host_name for hc in namenode_hc if hc.host_name][0]
print(namenode_host_name)

Answer 2

I have created a library to extract this information. Install with:
pip install --quiet --upgrade git+https://github.com/snowch/ibm-analytics-engine-python#master
Then run:
from ibm_analytics_engine import AmbariOperations
ambari_ops = AmbariOperations(vcap_filename='./vcap.json')
ambari_ops.get_namenode_hostname()