[jira] [Commented] (FLINK-5669) flink-streaming-contrib DataStreamUtils.collect in local environment mode fails when offline

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-5669?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15840741#comment-15840741 ] 

ASF GitHub Bot commented on FLINK-5669:
---------------------------------------

GitHub user rick-cox opened a pull request:

    https://github.com/apache/flink/pull/3223

    [FLINK-5669] Change DataStreamUtils to use the loopback address (127.0.0.1)

    For local environments, using loopback rather than the "local address" allows tests to run in
    situations where the local machine's hostname may not be resolvable in DNS
    (because DNS is unreachable or the hostname is not found) or the hostname does
    resolve, but not to an IP address that is reachable.
    
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You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/rick-cox/flink master

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/flink/pull/3223.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #3223
    
----
commit e12da9f1b2542fb1d5f862e1894c16ea834addcb
Author: Rick Cox <ri...@amazon.com>
Date:   2017-01-26T22:55:23Z

    [FLINK-5669] Change DataStreamUtils to use the loopback address (127.0.0.1) with local environments.
    
    Using loopback rather than the "local address" allows tests to run in
    situations where the local machine's hostname may not be resolvable in DNS
    (because DNS is unreacable or the hostname is not found) or the hostname does
    resolve, but not to an IP address that is reachable.

----


> flink-streaming-contrib DataStreamUtils.collect in local environment mode fails when offline
> --------------------------------------------------------------------------------------------
>
>                 Key: FLINK-5669
>                 URL: https://issues.apache.org/jira/browse/FLINK-5669
>             Project: Flink
>          Issue Type: Bug
>          Components: flink-contrib
>            Reporter: Rick Cox
>            Priority: Minor
>
> {{DataStreamUtils.collect()}} needs to obtain the local machine's IP so that the job can send the results back. In the case of local {{StreamEnvironments}}, it uses {{InetAddress.getLocalHost()}}, which attempts to resolve the local hostname using DNS.
> If DNS is not available (for example, when offline) or if DNS is available but cannot resolve the hostname (for example, if the hostname is an intranet name but the machine is not currently on that network), an {{UnknownHostException}} will be thrown (and wrapped in an {{IOException}}).
> If the resolved IP is not reachable for some reason, streaming results will fail.
> Since this case is for local execution only, it seems that using {{InetAddress.getLoopbackAddress()}} would work just as well, and avoid the assumptions made by {{getLocalHost()}}.



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