Ah, I see. I thought the RPC port was used for YARN’s own communication, but that field in ApplicationReport is exactly there for exposing some interfaces to the client, which is what I was looking for. I’ll take a look at MRAppMaster for an example. Thanks a lot for help!
Mingyu From: Sunil Govind <sunil.gov...@gmail.com> Date: Friday, June 10, 2016 at 5:37 AM To: Rohith Sharma K S <rohithsharm...@huawei.com>, Mingyu Kim <m...@palantir.com>, "user@hadoop.apache.org" <user@hadoop.apache.org> Cc: Matt Cheah <mch...@palantir.com> Subject: Re: Securely discovering Application Master's metadata or sending a secret to Application Master at submission Hi Mike Adding to what Rohith has mentioned, you can refer to below interface to know what all information which you can get from Yarn w.r.t one application. https://hadoop.apache.org/docs/r2.7.0/api/org/apache/hadoop/yarn/api/records/ApplicationReport.html This has RPC port ApplicationMaster, and you can try to interact AM through that. Being said this, its upto ApplicationMaster to expose interfaces which you are looking. And YARN doesnt have any control on same as mentioned by Rohith. - Sunil On Fri, Jun 10, 2016 at 11:26 AM Rohith Sharma K S <rohithsharm...@huawei.com> wrote: Hi Basically I see you have multiple questions 1. How to get AM RPC port ? >>> This you can get it via YarnClient# getApplicationReport(). This gives >>> common/generic application specific details. Note that RM does not maintain >>> any custom details for applications. 2. How can you get metadata of AM? >>> Basically AM design should be such that bind an interface to AM RPC. And >>> AM-RPC host and port can be obtained from ResourceManager. Using host:port >>> of AM from application submitter, connect to AM and get required details >>> from AM only. To achieve this , YARN does not provide any interface since >>> AM are written users. Essentially, user can design AM to expose client >>> interface to their clients. For your better understanding , see MapReduce >>> framework MRAppMaster. 3. About the authenticity of job-submitter to AM >>> Use secured hadoop cluster with Kerberos enabled. Note that AM also should >>> be implemented for handling Kerberos. Thanks & Regards Rohith Sharma K S From: Mingyu Kim [mailto:m...@palantir.com] Sent: 10 June 2016 03:47 To: Rohith Sharma K S; user@hadoop.apache.org Cc: Matt Cheah Subject: Re: Securely discovering Application Master's metadata or sending a secret to Application Master at submission Hi Rohith, Thanks for the pointers. I checked the Hadoop documentation you linked, but it’s not clear how I can expose client interface for providing metadata. By “YARN internal communications”, I was referring to the endpoints that are exposed by AM on the RPC port as reported in ApplicationReport. I assume either RM or containers will communicate with AM through these endpoints. I believe your suggestion is to expose additional endpoints to the AM RPC port. Can you clarify how I can do that? Is there an interface/class I need to extend? How can I register the extra endpoints for providing metadata on the existing AM RPC port? Mingyu From: Rohith Sharma K S <rohithsharm...@huawei.com> Date: Wednesday, June 8, 2016 at 11:15 PM To: Mingyu Kim <m...@palantir.com>, "user@hadoop.apache.org" <user@hadoop.apache.org> Cc: Matt Cheah <mch...@palantir.com> Subject: RE: Securely discovering Application Master's metadata or sending a secret to Application Master at submission Hi Do you know how I can extend the client interface of the RPC port? >>> YARN provides YARNClIent library that uses ApplicationClientProtocol. For >>> your more understanding refer >>> https://hadoop.apache.org/docs/stable/hadoop-yarn/hadoop-yarn-site/WritingYarnApplications.html#Writing_a_simple_Client I know AM has some endpoints exposed through the RPC port for internal YARN communications, but was not sure how I can extend it to expose a custom endpoint. >>> I am not sure what you mean here internal YARN communication? AM can >>> connect to RM only via AM-RM interface for register/unregister and >>> heartbeat and details sent to RM are limited. It is up to the AM’s to >>> expose client interface for providing metadata. Thanks & Regards Rohith Sharma K S From: Mingyu Kim [mailto:m...@palantir.com] Sent: 09 June 2016 11:21 To: Rohith Sharma K S; user@hadoop.apache.org Cc: Matt Cheah Subject: Re: Securely discovering Application Master's metadata or sending a secret to Application Master at submission Hi Rohith, Thanks for the quick response. That sounds promising. Do you know how I can extend the client interface of the RPC port? I know AM has some endpoints exposed through the RPC port for internal YARN communications, but was not sure how I can extend it to expose a custom endpoint. Any pointer would be appreciated! Mingyu From: Rohith Sharma K S <rohithsharm...@huawei.com> Date: Wednesday, June 8, 2016 at 10:39 PM To: Mingyu Kim <m...@palantir.com>, "user@hadoop.apache.org" <user@hadoop.apache.org> Cc: Matt Cheah <mch...@palantir.com> Subject: RE: Securely discovering Application Master's metadata or sending a secret to Application Master at submission Hi Apart from AM address and tracking URL, no other meta data of applicationMaster are stored in YARN. May be AM can expose client interface so that AM clients can interact with Running AM to retrieve specific AM details. RPC port of AM can be get from YARN client interface such as ApplicationClientProtocol# getApplicationReport() OR ApplicationClientProtocol #getApplicationAttemptReport(). Thanks & Regards Rohith Sharma K S From: Mingyu Kim [mailto:m...@palantir.com] Sent: 09 June 2016 10:36 To: user@hadoop.apache.org Cc: Matt Cheah Subject: Securely discovering Application Master's metadata or sending a secret to Application Master at submission Hi all, To provide a bit of background, I’m trying to deploy a REST server on Application Master and discover the randomly assigned port number securely. I can easily discover the host name of AM through YARN REST API, but the port number needs to be discovered separately. (Port number is assigned within a specified range with retries to avoid port conflicts) An easy solution would be to have Application Master make a callback with the port number, but I’d like to design it such that YARN nodes don’t talk back to the node that submitted the YARN application. So, this problem reduces to securely discovering a small metadata of Application Master. To be clear, by being secure, I’m less concerned about exposing the information to others, but more concerned about the integrity of data (e.g. the metadata actually originated from the Application Master.) I was hoping that there is a way to register some Application Master metadata to Resource Manager, but there doesn’t seem to be a way. Another option I considered was to write the information to a HDFS file, but in order to verify the integrity of the content, I need a way to securely send a private key to Application Master, which I’m not sure what the best is. To recap, does anyone know if there is a way · To register small metadata securely from Application Master to Resource Manager so that it can be discovered by the YARN application submitter? · Or, to securely send a private key to Application Master at the application submission time? Thanks a lot, Mingyu
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