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From "Elek, Marton (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-16312) Remove dumb-init from hadoop-runner image
Date Mon, 13 May 2019 10:55:00 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-16312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16838462#comment-16838462
] 

Elek, Marton commented on HADOOP-16312:
---------------------------------------

First of all, let me clarify that we are talking about this project: [https://github.com/Yelp/dumb-init]
{quote}Dumb-init is one way to always run contaized program in the background and respawn
the program when program fails
{quote}
Would you be so kind [~eyang] to explain it more details? Can you please give me an example
how scm process is _respawned_ in the ozone compose clusters (where hadoop-runner is used
together with dumb-init).

I ask it only because I have slightly different view of dumb-init (which may be wrong).

AFAIK dumb-init solves the signal handling problem and not the respawn problem. Without dumb-init
the containers can't be stopped gracefully. processes will be killed by docker daemon after
10 seconds with "kill -9".

> Remove dumb-init from hadoop-runner image
> -----------------------------------------
>
>                 Key: HADOOP-16312
>                 URL: https://issues.apache.org/jira/browse/HADOOP-16312
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Elek, Marton
>            Priority: Major
>
> This issue is reported by [~eyang] in HDDS-1495.
> I think it's better to discuss under a separated issue as it's unrelated to HDDS-1495.
> The original problem description from [~eyang]
> {quote}Dumb-init  is one way to always run contaized program in the background and respawn
the program when program fails. This is poor man’s solution for keeping program alive.
> Cluster management software like Kubernetes or YARN have additional policy and logic
to start the same docker container on a different node. Therefore, Dumb-init is not recommended
for future Hadoop daemons instead allow cluster management software to make decision where
to start the container. Dumb-init for demonize docker container will be removed, and change
to use entrypoint.sh Docker provides -d flag to demonize foreground process. Most of the management
system built on top of Docker, (ie. Kitematic, Apache YARN, and Kubernetes) integrates with
Docker container at foreground to  aggregate stdout and stderr output of the containerized
program.
> {quote}



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