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https://issues.apache.org/jira/browse/YARN-7935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16383204#comment-16383204
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Suma Shivaprasad commented on YARN-7935:
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Thanks [~leftnoteasy] for the review. Answers below
1) This patch introduces a new env CONTAINER_HOSTNAME which is se by NM in
prepareContainer. Even if an AM sets this, it will be overridden by NM in the
environment.
2) ContainerLaunch writes out the launch env immediately after calling
prepareContainer. User specified hostname in
YARN_CONTAINER_RUNTIME_DOCKER_CONTAINER_HOSTNAME
is given precedence as per earlier code flow and there is no change in this
behaviour in the current patch .
However there is change in --hostName behaviour in "host" mode. Earlier the
--hostName was being set to YARN defined hostname(generated from container_id)
which is incorrect in host network mode. In this patch, it is set to the NM's
host name which is the correct host name. Although docker seems to be ignoring
the --hostName set in "host" Mode in linux and promotes the /etc/hosts file
from the host, this is not the case in docker on Mac where it is honoring the
value passed in --hostName
> Expose container's hostname to applications running within the docker
> container
> -------------------------------------------------------------------------------
>
> Key: YARN-7935
> URL: https://issues.apache.org/jira/browse/YARN-7935
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: yarn
> Reporter: Suma Shivaprasad
> Assignee: Suma Shivaprasad
> Priority: Major
> Attachments: YARN-7935.1.patch, YARN-7935.2.patch, YARN-7935.3.patch
>
>
> Some applications have a need to bind to the container's hostname (like
> Spark) which is different from the NodeManager's hostname(NM_HOST which is
> available as an env during container launch) when launched through Docker
> runtime. The container's hostname can be exposed to applications via an env
> CONTAINER_HOSTNAME. Another potential candidate is the container's IP but
> this can be addressed in a separate jira.
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