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Posted to dev@ambari.apache.org by Robert Levas <rl...@hortonworks.com> on 2015/05/19 16:23:24 UTC

Review Request 34409: templeton.hive.properties property value substitution should be done by ambari-server

-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/34409/
-----------------------------------------------------------

Review request for Ambari.


Bugs: AMBARI-11202
    https://issues.apache.org/jira/browse/AMBARI-11202


Repository: ambari


Description
-------

The webhcat-site/templeton.hive.properties property value substitution should be done by ambari-server.  This value is more complicated than others since the (embedded) hive.metastore.uris property is a list of thrift URIs generated using the set of hosts the Hive Metastore is installed on.  This list of hosts comes from the clusterHostInfo/hive_metastore_host value, which in the KerberosHelper (org.apache.ambari.server.controller.KerberosHelper) is available as a comma-delimited list of hosts.

```
clusterHostInfo/hive_metastore_host = "host1,host2,host3"
```

To generate configuration values when enabling Kerberos, the KerberosHelper class uses org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables to replace variables specified in the Kerberos Descriptor.  Currently this mechanism uses a simple replacement scheme, which is not sufficient to generate string using a delimited list of values. 

In order to solve this issue, "functions" need to be applied to replacement data before making the substitution.  In this case a "function" named "each" will be created that takes the following arguments:
* pattern with placeholders
* delimiter to use to concatenate values generated using the patter
* regex to use to split the original string

For example (*commas are escaped when not intended to separate function args*): 

```
each(thrift://%s:9083, \,, \s*\,\s*)
```


To indicate this function is to be used, the following Kerberos Descriptor variable replacement syntax is to be used:
```
${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \,, \s*\,\s*)}
```
Note: \ characters need to be escaped in JSON structure values.  For example: 
```
"some.property" : "${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \\,, \s*\,\s*)}"
```

If clusterHostInfo/hive_metastore_host = "host1,host2,host3", the result would be 
```
thrift://host1:9083\,thrift://host2:9083\,thrift://host3:9083
```

As part of the solution, org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables was moved to org.apache.ambari.server.state.kerberos.VariableReplacementHelper#replaceVariables.


Diffs
-----

  ambari-server/src/main/java/org/apache/ambari/server/controller/KerberosHelper.java e083b0e 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/AbstractKerberosDescriptor.java b49fec1 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosKeytabDescriptor.java 404efa2 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosPrincipalDescriptor.java 6e5ac5c 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelper.java PRE-CREATION 
  ambari-server/src/main/resources/common-services/HIVE/0.12.0.2.0/kerberos.json 932b71b 
  ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/KerberosDescriptorTest.java 637facc 
  ambari-web/app/controllers/main/admin/kerberos/step4_controller.js a48baaf 

Diff: https://reviews.apache.org/r/34409/diff/


Testing
-------

Manually tested with 1 and 2 HiveMeta stores avaialble before enabled Kerberos, then adding an additional Hive MetaStore to see that the *each* function generated the correct value.

Added new unit tests


Thanks,

Robert Levas


Re: Review Request 34409: templeton.hive.properties property value substitution should be done by ambari-server

Posted by Emil Anca <ea...@hortonworks.com>.
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/34409/#review84516
-----------------------------------------------------------

Ship it!


LGTM. Expandable to support future prop formats as well.

- Emil Anca


On May 19, 2015, 7:06 p.m., Robert Levas wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/34409/
> -----------------------------------------------------------
> 
> (Updated May 19, 2015, 7:06 p.m.)
> 
> 
> Review request for Ambari, Emil Anca, John Speidel, and Robert Nettleton.
> 
> 
> Bugs: AMBARI-11202
>     https://issues.apache.org/jira/browse/AMBARI-11202
> 
> 
> Repository: ambari
> 
> 
> Description
> -------
> 
> The webhcat-site/templeton.hive.properties property value substitution should be done by ambari-server.  This value is more complicated than others since the (embedded) hive.metastore.uris property is a list of thrift URIs generated using the set of hosts the Hive Metastore is installed on.  This list of hosts comes from the clusterHostInfo/hive_metastore_host value, which in the KerberosHelper (org.apache.ambari.server.controller.KerberosHelper) is available as a comma-delimited list of hosts.
> 
> ```
> clusterHostInfo/hive_metastore_host = "host1,host2,host3"
> ```
> 
> To generate configuration values when enabling Kerberos, the KerberosHelper class uses org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables to replace variables specified in the Kerberos Descriptor.  Currently this mechanism uses a simple replacement scheme, which is not sufficient to generate string using a delimited list of values. 
> 
> In order to solve this issue, "functions" need to be applied to replacement data before making the substitution.  In this case a "function" named "each" will be created that takes the following arguments:
> * pattern with placeholders
> * delimiter to use to concatenate values generated using the patter
> * regex to use to split the original string
> 
> For example (*commas are escaped when not intended to separate function args*): 
> 
> ```
> each(thrift://%s:9083, \,, \s*\,\s*)
> ```
> 
> 
> To indicate this function is to be used, the following Kerberos Descriptor variable replacement syntax is to be used:
> ```
> ${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \,, \s*\,\s*)}
> ```
> Note: \ characters need to be escaped in JSON structure values.  For example: 
> ```
> "some.property" : "${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \\,, \s*\,\s*)}"
> ```
> 
> If clusterHostInfo/hive_metastore_host = "host1,host2,host3", the result would be 
> ```
> thrift://host1:9083\,thrift://host2:9083\,thrift://host3:9083
> ```
> 
> As part of the solution, org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables was moved to org.apache.ambari.server.state.kerberos.VariableReplacementHelper#replaceVariables.
> 
> 
> Diffs
> -----
> 
>   ambari-server/src/main/java/org/apache/ambari/server/controller/KerberosHelper.java e083b0e 
>   ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/AbstractKerberosDescriptor.java b49fec1 
>   ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosKeytabDescriptor.java 404efa2 
>   ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosPrincipalDescriptor.java 6e5ac5c 
>   ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelper.java PRE-CREATION 
>   ambari-server/src/main/resources/common-services/HIVE/0.12.0.2.0/kerberos.json 932b71b 
>   ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/KerberosDescriptorTest.java 637facc 
>   ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelperTest.java PRE-CREATION 
>   ambari-web/app/controllers/main/admin/kerberos/step4_controller.js a48baaf 
> 
> Diff: https://reviews.apache.org/r/34409/diff/
> 
> 
> Testing
> -------
> 
> Manually tested with 1 and 2 HiveMeta stores avaialble before enabled Kerberos, then adding an additional Hive MetaStore to see that the *each* function generated the correct value.
> 
> Added new unit tests
> 
> Running org.apache.ambari.server.state.kerberos.VariableReplacementHelperTest
> Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.14 sec
> 
> # Jenkins test results:
> 
> Running org.apache.ambari.server.state.kerberos.VariableReplacementHelperTest
> Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.168 sec
> 
> Tests run: 2996, Failures: 0, Errors: 0, Skipped: 21
> 
> [INFO] ------------------------------------------------------------------------
> [INFO] BUILD SUCCESS
> [INFO] ------------------------------------------------------------------------
> [INFO] Total time: 01:36 h
> [INFO] Finished at: 2015-05-19T17:28:39+00:00
> [INFO] Final Memory: 47M/516M
> [INFO] ------------------------------------------------------------------------
> 
> 
> Thanks,
> 
> Robert Levas
> 
>


Re: Review Request 34409: templeton.hive.properties property value substitution should be done by ambari-server

Posted by John Speidel <js...@hortonworks.com>.
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/34409/#review84513
-----------------------------------------------------------

Ship it!


Ship It!

- John Speidel


On May 19, 2015, 7:06 p.m., Robert Levas wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/34409/
> -----------------------------------------------------------
> 
> (Updated May 19, 2015, 7:06 p.m.)
> 
> 
> Review request for Ambari, Emil Anca, John Speidel, and Robert Nettleton.
> 
> 
> Bugs: AMBARI-11202
>     https://issues.apache.org/jira/browse/AMBARI-11202
> 
> 
> Repository: ambari
> 
> 
> Description
> -------
> 
> The webhcat-site/templeton.hive.properties property value substitution should be done by ambari-server.  This value is more complicated than others since the (embedded) hive.metastore.uris property is a list of thrift URIs generated using the set of hosts the Hive Metastore is installed on.  This list of hosts comes from the clusterHostInfo/hive_metastore_host value, which in the KerberosHelper (org.apache.ambari.server.controller.KerberosHelper) is available as a comma-delimited list of hosts.
> 
> ```
> clusterHostInfo/hive_metastore_host = "host1,host2,host3"
> ```
> 
> To generate configuration values when enabling Kerberos, the KerberosHelper class uses org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables to replace variables specified in the Kerberos Descriptor.  Currently this mechanism uses a simple replacement scheme, which is not sufficient to generate string using a delimited list of values. 
> 
> In order to solve this issue, "functions" need to be applied to replacement data before making the substitution.  In this case a "function" named "each" will be created that takes the following arguments:
> * pattern with placeholders
> * delimiter to use to concatenate values generated using the patter
> * regex to use to split the original string
> 
> For example (*commas are escaped when not intended to separate function args*): 
> 
> ```
> each(thrift://%s:9083, \,, \s*\,\s*)
> ```
> 
> 
> To indicate this function is to be used, the following Kerberos Descriptor variable replacement syntax is to be used:
> ```
> ${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \,, \s*\,\s*)}
> ```
> Note: \ characters need to be escaped in JSON structure values.  For example: 
> ```
> "some.property" : "${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \\,, \s*\,\s*)}"
> ```
> 
> If clusterHostInfo/hive_metastore_host = "host1,host2,host3", the result would be 
> ```
> thrift://host1:9083\,thrift://host2:9083\,thrift://host3:9083
> ```
> 
> As part of the solution, org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables was moved to org.apache.ambari.server.state.kerberos.VariableReplacementHelper#replaceVariables.
> 
> 
> Diffs
> -----
> 
>   ambari-server/src/main/java/org/apache/ambari/server/controller/KerberosHelper.java e083b0e 
>   ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/AbstractKerberosDescriptor.java b49fec1 
>   ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosKeytabDescriptor.java 404efa2 
>   ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosPrincipalDescriptor.java 6e5ac5c 
>   ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelper.java PRE-CREATION 
>   ambari-server/src/main/resources/common-services/HIVE/0.12.0.2.0/kerberos.json 932b71b 
>   ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/KerberosDescriptorTest.java 637facc 
>   ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelperTest.java PRE-CREATION 
>   ambari-web/app/controllers/main/admin/kerberos/step4_controller.js a48baaf 
> 
> Diff: https://reviews.apache.org/r/34409/diff/
> 
> 
> Testing
> -------
> 
> Manually tested with 1 and 2 HiveMeta stores avaialble before enabled Kerberos, then adding an additional Hive MetaStore to see that the *each* function generated the correct value.
> 
> Added new unit tests
> 
> Running org.apache.ambari.server.state.kerberos.VariableReplacementHelperTest
> Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.14 sec
> 
> # Jenkins test results:
> 
> Running org.apache.ambari.server.state.kerberos.VariableReplacementHelperTest
> Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.168 sec
> 
> Tests run: 2996, Failures: 0, Errors: 0, Skipped: 21
> 
> [INFO] ------------------------------------------------------------------------
> [INFO] BUILD SUCCESS
> [INFO] ------------------------------------------------------------------------
> [INFO] Total time: 01:36 h
> [INFO] Finished at: 2015-05-19T17:28:39+00:00
> [INFO] Final Memory: 47M/516M
> [INFO] ------------------------------------------------------------------------
> 
> 
> Thanks,
> 
> Robert Levas
> 
>


Re: Review Request 34409: templeton.hive.properties property value substitution should be done by ambari-server

Posted by Robert Levas <rl...@hortonworks.com>.
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/34409/
-----------------------------------------------------------

(Updated May 19, 2015, 3:06 p.m.)


Review request for Ambari, Emil Anca, John Speidel, and Robert Nettleton.


Bugs: AMBARI-11202
    https://issues.apache.org/jira/browse/AMBARI-11202


Repository: ambari


Description
-------

The webhcat-site/templeton.hive.properties property value substitution should be done by ambari-server.  This value is more complicated than others since the (embedded) hive.metastore.uris property is a list of thrift URIs generated using the set of hosts the Hive Metastore is installed on.  This list of hosts comes from the clusterHostInfo/hive_metastore_host value, which in the KerberosHelper (org.apache.ambari.server.controller.KerberosHelper) is available as a comma-delimited list of hosts.

```
clusterHostInfo/hive_metastore_host = "host1,host2,host3"
```

To generate configuration values when enabling Kerberos, the KerberosHelper class uses org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables to replace variables specified in the Kerberos Descriptor.  Currently this mechanism uses a simple replacement scheme, which is not sufficient to generate string using a delimited list of values. 

In order to solve this issue, "functions" need to be applied to replacement data before making the substitution.  In this case a "function" named "each" will be created that takes the following arguments:
* pattern with placeholders
* delimiter to use to concatenate values generated using the patter
* regex to use to split the original string

For example (*commas are escaped when not intended to separate function args*): 

```
each(thrift://%s:9083, \,, \s*\,\s*)
```


To indicate this function is to be used, the following Kerberos Descriptor variable replacement syntax is to be used:
```
${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \,, \s*\,\s*)}
```
Note: \ characters need to be escaped in JSON structure values.  For example: 
```
"some.property" : "${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \\,, \s*\,\s*)}"
```

If clusterHostInfo/hive_metastore_host = "host1,host2,host3", the result would be 
```
thrift://host1:9083\,thrift://host2:9083\,thrift://host3:9083
```

As part of the solution, org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables was moved to org.apache.ambari.server.state.kerberos.VariableReplacementHelper#replaceVariables.


Diffs
-----

  ambari-server/src/main/java/org/apache/ambari/server/controller/KerberosHelper.java e083b0e 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/AbstractKerberosDescriptor.java b49fec1 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosKeytabDescriptor.java 404efa2 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosPrincipalDescriptor.java 6e5ac5c 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelper.java PRE-CREATION 
  ambari-server/src/main/resources/common-services/HIVE/0.12.0.2.0/kerberos.json 932b71b 
  ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/KerberosDescriptorTest.java 637facc 
  ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelperTest.java PRE-CREATION 
  ambari-web/app/controllers/main/admin/kerberos/step4_controller.js a48baaf 

Diff: https://reviews.apache.org/r/34409/diff/


Testing (updated)
-------

Manually tested with 1 and 2 HiveMeta stores avaialble before enabled Kerberos, then adding an additional Hive MetaStore to see that the *each* function generated the correct value.

Added new unit tests

Running org.apache.ambari.server.state.kerberos.VariableReplacementHelperTest
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.14 sec

# Jenkins test results:

Running org.apache.ambari.server.state.kerberos.VariableReplacementHelperTest
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.168 sec

Tests run: 2996, Failures: 0, Errors: 0, Skipped: 21

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 01:36 h
[INFO] Finished at: 2015-05-19T17:28:39+00:00
[INFO] Final Memory: 47M/516M
[INFO] ------------------------------------------------------------------------


Thanks,

Robert Levas


Re: Review Request 34409: templeton.hive.properties property value substitution should be done by ambari-server

Posted by Robert Levas <rl...@hortonworks.com>.
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/34409/
-----------------------------------------------------------

(Updated May 19, 2015, 11:14 a.m.)


Review request for Ambari, Emil Anca, John Speidel, and Robert Nettleton.


Bugs: AMBARI-11202
    https://issues.apache.org/jira/browse/AMBARI-11202


Repository: ambari


Description
-------

The webhcat-site/templeton.hive.properties property value substitution should be done by ambari-server.  This value is more complicated than others since the (embedded) hive.metastore.uris property is a list of thrift URIs generated using the set of hosts the Hive Metastore is installed on.  This list of hosts comes from the clusterHostInfo/hive_metastore_host value, which in the KerberosHelper (org.apache.ambari.server.controller.KerberosHelper) is available as a comma-delimited list of hosts.

```
clusterHostInfo/hive_metastore_host = "host1,host2,host3"
```

To generate configuration values when enabling Kerberos, the KerberosHelper class uses org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables to replace variables specified in the Kerberos Descriptor.  Currently this mechanism uses a simple replacement scheme, which is not sufficient to generate string using a delimited list of values. 

In order to solve this issue, "functions" need to be applied to replacement data before making the substitution.  In this case a "function" named "each" will be created that takes the following arguments:
* pattern with placeholders
* delimiter to use to concatenate values generated using the patter
* regex to use to split the original string

For example (*commas are escaped when not intended to separate function args*): 

```
each(thrift://%s:9083, \,, \s*\,\s*)
```


To indicate this function is to be used, the following Kerberos Descriptor variable replacement syntax is to be used:
```
${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \,, \s*\,\s*)}
```
Note: \ characters need to be escaped in JSON structure values.  For example: 
```
"some.property" : "${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \\,, \s*\,\s*)}"
```

If clusterHostInfo/hive_metastore_host = "host1,host2,host3", the result would be 
```
thrift://host1:9083\,thrift://host2:9083\,thrift://host3:9083
```

As part of the solution, org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables was moved to org.apache.ambari.server.state.kerberos.VariableReplacementHelper#replaceVariables.


Diffs
-----

  ambari-server/src/main/java/org/apache/ambari/server/controller/KerberosHelper.java e083b0e 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/AbstractKerberosDescriptor.java b49fec1 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosKeytabDescriptor.java 404efa2 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosPrincipalDescriptor.java 6e5ac5c 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelper.java PRE-CREATION 
  ambari-server/src/main/resources/common-services/HIVE/0.12.0.2.0/kerberos.json 932b71b 
  ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/KerberosDescriptorTest.java 637facc 
  ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelperTest.java PRE-CREATION 
  ambari-web/app/controllers/main/admin/kerberos/step4_controller.js a48baaf 

Diff: https://reviews.apache.org/r/34409/diff/


Testing (updated)
-------

Manually tested with 1 and 2 HiveMeta stores avaialble before enabled Kerberos, then adding an additional Hive MetaStore to see that the *each* function generated the correct value.

Added new unit tests

Running org.apache.ambari.server.state.kerberos.VariableReplacementHelperTest
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.14 sec

# Jenkins test results: PENDING


Thanks,

Robert Levas


Re: Review Request 34409: templeton.hive.properties property value substitution should be done by ambari-server

Posted by Robert Levas <rl...@hortonworks.com>.
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/34409/
-----------------------------------------------------------

(Updated May 19, 2015, 11:13 a.m.)


Review request for Ambari, Emil Anca, John Speidel, and Robert Nettleton.


Bugs: AMBARI-11202
    https://issues.apache.org/jira/browse/AMBARI-11202


Repository: ambari


Description
-------

The webhcat-site/templeton.hive.properties property value substitution should be done by ambari-server.  This value is more complicated than others since the (embedded) hive.metastore.uris property is a list of thrift URIs generated using the set of hosts the Hive Metastore is installed on.  This list of hosts comes from the clusterHostInfo/hive_metastore_host value, which in the KerberosHelper (org.apache.ambari.server.controller.KerberosHelper) is available as a comma-delimited list of hosts.

```
clusterHostInfo/hive_metastore_host = "host1,host2,host3"
```

To generate configuration values when enabling Kerberos, the KerberosHelper class uses org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables to replace variables specified in the Kerberos Descriptor.  Currently this mechanism uses a simple replacement scheme, which is not sufficient to generate string using a delimited list of values. 

In order to solve this issue, "functions" need to be applied to replacement data before making the substitution.  In this case a "function" named "each" will be created that takes the following arguments:
* pattern with placeholders
* delimiter to use to concatenate values generated using the patter
* regex to use to split the original string

For example (*commas are escaped when not intended to separate function args*): 

```
each(thrift://%s:9083, \,, \s*\,\s*)
```


To indicate this function is to be used, the following Kerberos Descriptor variable replacement syntax is to be used:
```
${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \,, \s*\,\s*)}
```
Note: \ characters need to be escaped in JSON structure values.  For example: 
```
"some.property" : "${clusterHostInfo/hive_metastore_host|each(thrift://%s:9083, \\,, \s*\,\s*)}"
```

If clusterHostInfo/hive_metastore_host = "host1,host2,host3", the result would be 
```
thrift://host1:9083\,thrift://host2:9083\,thrift://host3:9083
```

As part of the solution, org.apache.ambari.server.state.kerberos.AbstractKerberosDescriptor#replaceVariables was moved to org.apache.ambari.server.state.kerberos.VariableReplacementHelper#replaceVariables.


Diffs (updated)
-----

  ambari-server/src/main/java/org/apache/ambari/server/controller/KerberosHelper.java e083b0e 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/AbstractKerberosDescriptor.java b49fec1 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosKeytabDescriptor.java 404efa2 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/KerberosPrincipalDescriptor.java 6e5ac5c 
  ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelper.java PRE-CREATION 
  ambari-server/src/main/resources/common-services/HIVE/0.12.0.2.0/kerberos.json 932b71b 
  ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/KerberosDescriptorTest.java 637facc 
  ambari-server/src/test/java/org/apache/ambari/server/state/kerberos/VariableReplacementHelperTest.java PRE-CREATION 
  ambari-web/app/controllers/main/admin/kerberos/step4_controller.js a48baaf 

Diff: https://reviews.apache.org/r/34409/diff/


Testing
-------

Manually tested with 1 and 2 HiveMeta stores avaialble before enabled Kerberos, then adding an additional Hive MetaStore to see that the *each* function generated the correct value.

Added new unit tests


Thanks,

Robert Levas