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https://issues.apache.org/jira/browse/HADOOP-13628?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15510857#comment-15510857
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Weiwei Yang commented on HADOOP-13628:
--------------------------------------
v3 patch has following updates
* Supported both JSON and XML format of response
* Added some tests in {{TestConfServlet#testGetProperty}}, use some mockups to
test the API
* Query for a non-exist configuration property will get a 404 error now
* Extracted some common code in {{Configuration}} for reuse, such as
{{Configuration#appendXMLProperty}} and {{Configuration#appendJSONProperty}}
* Improved java doc
Some more explanation to the behaviors. When you want to query for a property,
issue following command
{code}
curl --header "accept: application/xml"
http://deale1.fyre.ibm.com:8088/conf?name=yarn.ipc.rpc.class
Output:
<property><name>yarn.ipc.rpc.class</name><value>org.apache.hadoop.yarn.ipc.HadoopYarnProtoRPC</value><final>false</final><source>yarn-default.xml</source></property>
{code}
if you want to get a json output, just modify the header
{code}
curl --header "accept: application/json"
http://deale1.fyre.ibm.com:8088/conf?name=yarn.ipc.rpc.class
Output:
{"property":{"key":"yarn.ipc.rpc.class","value":"org.apache.hadoop.yarn.ipc.HadoopYarnProtoRPC","isFinal":false,"resource":"yarn-default.xml"}}
{code}
if you provided a non-exist property name
{code}
curl --header "accept: application/xml"
http://deale1.fyre.ibm.com:8088/conf?name=unknown.property
Output:
...
<title>Error 404 Property unknown.property not found</title>
</head>
<body><h2>HTTP ERROR 404</h2>
<p>Problem accessing /conf. Reason:
<pre> Property unknown.property not found</pre></p><hr /><i><small>Powered
by Jetty://</small></i><br/>
<br/>
{code}
if you did not provide any value to {{name}} parameter, or did not use it, it
behaves just like before, dump all configuration properties. So following
commands will get same output
{code}
curl --header "accept: application/xml"
http://deale1.fyre.ibm.com:8088/conf?name="";
curl --header "accept: application/xml"
http://deale1.fyre.ibm.com:8088/conf?name=
curl --header "accept: application/xml" http://deale1.fyre.ibm.com:8088/conf
Output:
All properties...
{code}
> Support to retrieve specific property from configuration via REST API
> ---------------------------------------------------------------------
>
> Key: HADOOP-13628
> URL: https://issues.apache.org/jira/browse/HADOOP-13628
> Project: Hadoop Common
> Issue Type: Improvement
> Components: conf
> Affects Versions: 2.7.3
> Reporter: Weiwei Yang
> Assignee: Weiwei Yang
> Attachments: HADOOP-13628.01.patch, HADOOP-13628.02.patch,
> HADOOP-13628.03.patch
>
>
> Currently we can use rest API to retrieve all configuration properties per
> daemon, but unable to get a specific property by name. This causes extra
> parse work at client side when dealing with Hadoop configurations, and also
> it's quite over head to send all configuration in a http response over
> network. Propose to support following a {{name}} parameter in the http
> request, by issuing
> {code}
> curl --header "Accept:application/json"
> http://${RM_HOST}/conf?name=yarn.nodemanager.aux-services
> {code}
> get output
> {code}
> {"property"{"key":"yarn.resourcemanager.hostname","value":"${RM_HOST}","isFinal":false,"resource":"yarn-site.xml"}}
> {code}
> This change is fully backwards compatible.
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