[jira] [Reopened] (HADOOP-9562) Create REST interface for HDFS health data

["Steve Loughran (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-9562?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steve Loughran reopened HADOOP-9562:
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I'm actually reopening this because there's a difference between a REST API to get JMX values vs a simple happy page which can return 200/500 based on server health.

In particular, look at the [Codahale health servlet|https://dropwizard.github.io/metrics/3.1.0/manual/servlets/] ... you implement a health check method & codahale aggregates them and views the system as healthy if they are all happy. It's a simple binary view, limited in many ways (excessive load/response time ==> unhealthy), but it allows for foundational liveness checks "dns resolving, disk space there, kerberos credentials not expired"

We don't have a similar health check model in the hadoop metrics

> Create REST interface for HDFS health data
> ------------------------------------------
>
>                 Key: HADOOP-9562
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9562
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: fs
>    Affects Versions: 2.0.4-alpha, 3.0.0
>            Reporter: Trevor Lorimer
>            Priority: Minor
>              Labels: BB2015-05-TBR
>         Attachments: HADOOP-9562.diff, HADOOP-9562.patch
>
>
> The HDFS health screen (dfshealth.jsp) displays basic Version, Security and Health information concerning the NameNode, currently this information is accessible from classes in the org.apache.hadoop,hdfs.server.namenode package and cannot be accessed outside the NameNode. This becomes prevalent if the data is required to be displayed using a new user interface.
> The proposal is to create a REST interface to expose the NameNode information displayed on dfshealth.jsp using GET methods. Wrapper classes will be created to serve the data to the REST root resource within the hadoop-hdfs project.
> This will enable the HDFS health screen information to be accessed remotely.



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