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From "Shane Kumpf (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-7987) Docker container name(--name) needs to be DNS friendly for DNS resolution to work in user defined networks.
Date Fri, 02 Mar 2018 19:25:00 GMT

    [ https://issues.apache.org/jira/browse/YARN-7987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16384026#comment-16384026

Shane Kumpf commented on YARN-7987:

Thanks for testing out that flag [~suma.shivaprasad]! I'm glad to hear this looks like a possible
option to avoid changing the container name.

network-alias is not a valid option in the "default bridge"and "host" networking modes and
adding this flag fails. Will need to check and add this to docker container runs only in the
case of user defined networks.
Makes sense. User's can modify the default bridge, so I think we'll need to consider that
case. I believe we could look at {{com.docker.network.bridge.default_bridge}} in {{docker
network inspect <name>}} to determine if the supplied network is the default bridge
and avoid the flag in that case.

However, since the YARN generated hostnames (generated from container-id) are unique, this
should not be a major issue IMO. 
I agree, I don't think that's a situation we would run into.

> Docker container name(--name) needs to be DNS friendly for DNS resolution to work in
user defined networks. 
> ------------------------------------------------------------------------------------------------------------
>                 Key: YARN-7987
>                 URL: https://issues.apache.org/jira/browse/YARN-7987
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>            Reporter: Suma Shivaprasad
>            Assignee: Suma Shivaprasad
>            Priority: Major
> User defined networks like overlays support DNS resolution through Docker Embedded DNS
which needs the container name (–name parameter value in docker run) to be a FQDN for container
names to be resolved - Please refer documentation [https://docs.docker.com/v17.09/engine/userguide/networking/configure-dns/]
> However Yarn sets the container name to the container's id which is not DNS friendly(eg: container_e26_1519402686002_0035_01_000003)
and is not a FQDN. 
> The proposal is to set a FQDN(eg: ctr-e26-1519402686002-0035-01-000003.domain-name)
as the docker container's name for containers to be able to communicate to each other via
hostnames in user defined networks like overlays, bridges etc. The domain name will be picked
up from the YARN DNS registry configuration (hadoop.registry.dns.domain-name)

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