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https://issues.apache.org/jira/browse/YARN-8380?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16551033#comment-16551033
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Billie Rinaldi commented on YARN-8380:
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Ah, I see. I didn't realize some of the options were propagation options. I
read over [https://docs.docker.com/storage/bind-mounts/] and it leads me to
believe the following:
* rw and ro are the "base" mode. If not specified, rw is assumed.
* In addition to the "base" mode, a single bind propagation option can be
specified (shared, rshared, slave, rslave, private, rprivate).
* z and Z are options that modify the SELinux label of the host file being
mounted into the container. It says to use extreme caution with these and
sounds like we shouldn't allow them.
* consistent, default, delegated, and cached are options that configure mount
consistency in Mac OS X, so probably we don't need these.
* nocopy is an option that controls whether data is copied from the container
into the Docker volume on the host. It does not apply to bind mounts (files or
directories not managed by Docker that already exist on the host) because
copying is not performed for bind mounts. It seems like we are only supporting
bind mounts at this point, but perhaps we should consider whether we would want
to support Docker volumes in the future.
Based on this analysis, the mount options the Docker runtime could parse from
the user on the Java side are:
# source:target:(rw|ro)
# source:target:(rw|ro),(r?shared|r?slave|r?private)
# source:target – here rw is assumed
# source:target:(r?shared|r?slave|r?private) – here rw is assumed
One question is whether we want to allow formats 3 and 4, or only allow 1 and 2
so the user has to specify rw explicitly (note that currently the user has to
specify :ro or :rw). If we required format 1 or 2, to get a shared mount the
user would specify source:target:rw,shared or source:target:ro,shared.
On the container-executor side, we can assume format 1 or 2 since it will have
been converted on the Java side. It looks like I should parse the mount type to
see if it has a bind propagation option or not. I am thinking that we should
keep the original configs docker.allowed.rw-mounts and docker.allowed.ro-mounts
and allow any of the bind propagation options (which I believe is what [~eyang]
is suggesting). It seems like we might not need additional configs controlling
whether the propagation options are allowed. What do you think? The propagation
options are outlined here:
[https://docs.docker.com/storage/bind-mounts/#configure-bind-propagation].
> Support shared mounts in docker runtime
> ---------------------------------------
>
> Key: YARN-8380
> URL: https://issues.apache.org/jira/browse/YARN-8380
> Project: Hadoop YARN
> Issue Type: Bug
> Reporter: Billie Rinaldi
> Assignee: Billie Rinaldi
> Priority: Major
> Attachments: YARN-8380.1.patch, YARN-8380.2.patch
>
>
> The docker run command supports the mount type shared, but currently we are
> only supporting ro and rw mount types in the docker runtime.
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