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