...

Currently, topology services can accommodate proxying the corresponding HA-enabled cluster services using topology configuration or by leveraging ZooKeeper; the means depends on the cluster service.
For example, the WEBHDFS service is configured with URLs in the service declaration while the HIVE service employs the list of hosts in the configured ZooKeeper ensemble:

...
  <provider>
    <role>ha</role>
    <name>HaProvider</name>
    <enabled>true</enabled>
    <param>
      <name>WEBHDFS</name>
      <value>maxFailoverAttempts=3;failoverSleep=1000;maxRetryAttempts=300;retrySleep=1000;enabled=true</value>
    </param>
    <param>
      <name>HIVE</name>
      <value>maxFailoverAttempts=3;failoverSleep=1000;enabled=true;zookeeperEnsemble=host1:2181,host2:2181,host3:2181;zookeeperNamespace=hiveserver2</value>
    </param>
  </provider>
</gateway>

<service>
  <role>WEBHDFS</role>
  <url>http://host1:50070/webhdfs</url>
  <url>http://host2:50070/webhdfs</url>
</service>
 
<service>
  <role>HIVE</role>
</service>
...

...

yarn.resourcemanager.ha.enabled

yarn.resourcemanager.zk-address

Required Changes

Required Changes

• Knox will parse referenced provider configurations, rather than just blindly copying their contents.
  This will serve multiple purposes:
  • It will provide a degree of validation (invalid provider configurations would fail parsing)
  • It will allow
  Knox will parse referenced provider configurations, rather than just blindly copying their contents.
  This will serve multiple purposes:
  • It will provide a degree of validation (invalid provider configurations would fail parsing)
  • It will allow a finer level of control over what is serialized to the generated topology file:
    • Knox will have the opportunity to add cluster-specific details into provider configuration in the generated topologies
    • Knox could add/modify the HaProvider config based on cluster details (e.g., HA enabled for a particular service)
    • Knox could reference elements of the provider configuration (e.g., HaProvider) to inform the generation of service elements in the generated topologies.

• Move cluster-specific service HA configuration from the HaProvider configuration to the service declaration.
  
  • This just makes more logical sense
  • Moving cluster-specific details out of the provider configuration will make shared provider configurations applicable to more topologies (i.e., more reusable), across clusters.
  • The cluster-specific configuration could be discovered along with the service URL details, rather than having to be hard-coded in a provider configuration.
  • This will be treated as override configuration, so that the existing approach (i.e., complete configuration as HaProvider param values) will continue to work, to satisfy backward-compatibility requirements.
    

Open Items

...

• • 
    

• Support new enabled value "auto" to allow service-specific configuration to determine whether HA treatment is enabled for that service.

  Code Block
  language xml title Example HaProvider Configuration with enabled=auto
  <provider> <role>ha</role> <name>HaProvider</name> <enabled>true</enabled> <param> <name>WEBHDFS</name> <value>maxFailoverAttempts=3;failoverSleep=1000;maxRetryAttempts=300;retrySleep=1000;enabled=auto</value> </param> </provider>

  In this case, the topology generation will reference the dfs.ha.automatic-failover.enabled property in the HDFS configuration to determine whether the HaProvider should be enabled for WEBHDFS.
  
  

Open Items

• Identify the nature of all the supported services
  • Which services are currently purely topology-based (DefaultURLManager)?
    
    • WEBHCAT
    • OOZIE
    • WEBHDFS
    • ?
      
      
  • Which services are currently ZooKeeper-based (BaseZooKeeperURLManager)?
    • HIVE (HS2ZooKeeperURLManager)
    • HBASE (HBaseZooKeeperURLManager)
    • Kafka (KafkaZooKeeperURLManager)
    • SOLR (SOLRZooKeeperURLManager)
    • ATLAS (AtlasZookeeperURLManager)
      
      
  • Could ZooKeeper support be added for any services which do no currently support it?
    • These have zookeeper-related configuration (see table):
      • WEBHDFS
      • OOZIE
      • YARN
      • WEBHCAT
      • RESOURCEMANAGER
        
        
        
• For the ZooKeeper-based-HA services, determine if the ZooKeeper details are available from the service's configuration via Ambari.
  
  
• Can "HA mode" be determined for every service type from the cluster configuration details? Can Knox dynamically identify HA-configured services, and generate the topology accordingly?
  
  
• Determine how to leverage the cluster discovery data to generate the ZooKeeper HA configuration for the relevant declared topology services.

Proposed Alternative Provider Configuration File Formats

JSON

{
  "providers": [
    {
      "role":"authentication",
      "name":"ShiroProvider",
      "enabled":"true",
      "params":{
        "sessionTimeout":"30",
        "main.ldapRealm":"org.apache.hadoop.gateway.shirorealm.KnoxLdapRealm",
        "main.ldapContextFactory":"org.apache.hadoop.gateway.shirorealm.KnoxLdapContextFactory",
        "main.ldapRealm.contextFactory":"$ldapContextFactory",
        "main.ldapRealm.userDnTemplate":"uid={0},ou=people,dc=hadoop,dc=apache,dc=org",
    	"main.ldapRealm.contextFactory.url":"ldap://localhost:33389",
	    "main.ldapRealm.contextFactory.authenticationMechanism":"simple",
	    "urls./**":"authcBasic"
	  }
    },
	{
	  "role":"hostmap",
	  "name":"static",
	  "enabled":"true",
	  "params":{
	    "localhost":"sandbox,sandbox.hortonworks.com"
	  }
	},
	{
	  "role":"ha",
	  "name":"HaProvider",
	  "enabled":"true",
	  "params":{
	    "WEBHDFS":"maxFailoverAttempts=3;failoverSleep=1000;maxRetryAttempts=300;retrySleep=1000;enabled=true",
		"HIVE":"maxFailoverAttempts=3;failoverSleep=1000;enabled=true"
	  }
	}
  ]
}

YAML 

---
providers:
  - role: authentication
    name: ShiroProvider
    enabled: true
    params:
      sessionTimeout: 30
      main.ldapRealm: 

Proposed Alternative Provider Configuration File Formats

JSON

{
  "providers": [
    {
      "role":"authentication",
      "name":"ShiroProvider",
      "enabled":"true",
      "params":{
        "sessionTimeout":"30",
        "main.ldapRealm":"org.apache.hadoop.gateway.shirorealm.KnoxLdapRealm",
        "main.ldapContextFactory":" org.apache.hadoop.gateway.shirorealm.KnoxLdapContextFactory",
        "main.ldapRealm.contextFactory":" $ldapContextFactory",
        "main.ldapRealm.userDnTemplate":" uid={0},ou=people,dc=hadoop,dc=apache,dc=org",
     	" main.ldapRealm.contextFactory.url":" ldap://localhost:33389",
	      "main.ldapRealm.contextFactory.authenticationMechanism":" simple",
	      "urls./**":" authcBasic"
	  }
-    },
	{
	  "role":"hostmap",
	  "name":"static",
	  "enabled":"true",
	  "params":{
	role: hostmap
    name: static
    enabled: true
    params:
      "localhost":" sandbox,sandbox.hortonworks.com"
	  }
	},
	{
	  "role":"ha",
	  "name":"HaProvider",
	  "enabled":"true",
	  "params":{
	    "WEBHDFS":"- role: ha
    name: HaProvider
    enabled: true
    params:           # No cluster-specific details here
      WEBHDFS: maxFailoverAttempts=3;failoverSleep=1000;maxRetryAttempts=300;retrySleep=1000;enabled=true",
		"HIVE":"
      HIVE: maxFailoverAttempts=3;failoverSleep=1000;enabled=true"
	  }
	}
  ]
}

...

---
discovery-address: http://localhost:8080
discovery-user: maria_dev
provider-config-ref: sandbox-providers
cluster: Sandbox

services:
    - name: NAMENODE
    - name: JOBTRACKER
    - name: WEBHDFS---
providers:
  - role: authentication
    name: ShiroProvider
    enabled: true
      params:
        sessionTimeoutmaxFailoverAttempts: 305
        main.ldapRealmmaxRetryAttempts: org.apache.hadoop.gateway.shirorealm.KnoxLdapRealm
5
       main.ldapContextFactory: org.apache.hadoop.gateway.shirorealm.KnoxLdapContextFactory failoverSleep: 1001
      main.ldapRealm.contextFactory- name: $ldapContextFactoryWEBHBASE
      main.ldapRealm.userDnTemplate: uid={0},ou=people,dc=hadoop,dc=apache,dc=org- name: HIVE
      main.ldapRealm.contextFactory.url: ldap://localhost:33389
params:
        haEnabled: true
        main.ldapRealm.contextFactory.authenticationMechanismmaxFailoverAttempts: simple5
      urls./**  maxRetryAttempts: authcBasic5
  - role: hostmap
    namefailoverSleep: static1001
    enabled: true
   zookeeperNamespace: params:
hiveserver2      localhost: sandbox,sandbox.hortonworks.com
  - role: ha
    name: HaProvider
    enabled: true
    params:
      WEBHDFS: maxFailoverAttempts=3;failoverSleep=1000;maxRetryAttempts=300;retrySleep=1000;enabled=true
      HIVE: maxFailoverAttempts=3;failoverSleep=1000;enabled=true

---
discovery-address            # Optionally, omit this, and Knox could discover it
        zookeeperEnsemble: http://localhost:8080
discovery-user: maria_dev
provider-config-ref: sandbox-providers
cluster: Sandbox

services:
    - name: NAMENODE
    - name: JOBTRACKERhost1:2181,http://host2:2181,http://host3:2181  # Optionally, omit this, and Knox could discover it
    - name: RESOURCEMANAGER
 

{
  "discovery-address":"http://localhost:8080",
  "discovery-user":"maria_dev",
  "provider-config-ref":"sandbox-providers",
  "cluster":"Sandbox",
  "services":[
    {"name":"NAMENODE"},
    {"name":"JOBTRACKER"},
    {"name":"WEBHDFS",
 WEBHDFS
      params:
        maxFailoverAttempts: 5
        maxRetryAttempts: 5
        failoverSleep: 1001
    - name: WEBHBASE
    - name: HIVE
      "params": {
        "maxFailoverAttempts": "5",
        "maxRetryAttempts": "5",
        "failoverSleep": "1001"
       }
    },
    {"name":"WEBHBASE"},
    zookeeperNamespace: hiveserver2{"name":"HIVE",
        zookeeperEnsemble: http://host1:2181,http://host2:2181,http://host3:2181"params": {
    -   name: RESOURCEMANAGER
 

{
  "discovery-address":"http://localhost:8080",
  "discovery-user":"maria_dev",
  "provider-config-ref":"sandbox-providers",
  "cluster":"Sandbox",
  "services":[
    {"name":"NAMENODE"},
    {"name":"JOBTRACKER" "haEnabled": "true",
        "maxFailoverAttempts": "4",
        "maxRetryAttempts": "6",
        "failoverSleep": "5000",
        "zookeeperNamespace": "hiveserver2",
        "zookeeperEnsemble": "http://host1:2181,http://host2:2181,http://host3:2181"
       }
    },
    {"name":"WEBHDFSRESOURCEMANAGER",}
  ]
}

...
  <provider>
   "params": {
  <role>ha</role>
    <name>HaProvider</name>
   "maxFailoverAttempts": "5",
 <enabled>true</enabled>
    <param>
     "maxRetryAttempts": "5", <name>WEBHDFS</name>
      <!--  "failoverSleep": "1001"
       }
    },
    {"name":"WEBHBASE"},
    {"name":"HIVE",No cluster-specific details here -->
      <value>maxFailoverAttempts=3;failoverSleep=1000;maxRetryAttempts=300;retrySleep=1000;enabled=true</value>
    </param>
    <param>
       "params": {
<name>HIVE</name>
      <!-- No cluster-specific details "maxFailoverAttempts": "4",
   here -->
      <value>maxFailoverAttempts=3;failoverSleep=1000;enabled=true</value>
     "maxRetryAttempts": "6",</param>
  </provider>
</gateway>

<service>
  <role>WEBHDFS</role>
  <url>http://host1:50070/webhdfs</url>
    "failoverSleep": "5000",
        "zookeeperNamespace": "hiveserver2",<url>http://host2:50070/webhdfs</url>
</service>

<service>
  <role>HIVE</role>
  <!-- Cluster-specific details here -->
  <param>
    <name>zookeeperEnsemble</name>
    "zookeeperEnsemble": "http://host1<value>host1:2181,host2:2181,httphost3:2181<//host2:2181,http://host3:2181"value>
  </param>
  <param>
    <name>zookeeperNamespace</name>
    <value>hiveserver2</value>
  </param>
  }<param>
    },<name>haEnabled</name>
    {"name":"RESOURCEMANAGER"}<value>true</value>
  ]
}

...

</param>



</service>
...