Ivan Mitic created HADOOP-8731:
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Summary: Public distributed cache support for Windows
Key: HADOOP-8731
URL: https://issues.apache.org/jira/browse/HADOOP-8731
Project: Hadoop Common
Issue Type: Bug
Components: filecache
Reporter: Ivan Mitic
Assignee: Ivan Mitic
A distributed cache file is considered public (sharable between MR jobs) if
OTHER has read permissions on the file and +x permissions all the way up in the
folder hierarchy. By default, Windows permissions are mapped to "700" all the
way up to the drive letter, and it is unreasonable to ask users to change the
permission on the whole drive to make the file public. IOW, it is hardly
possible to have public distributed cache on Windows.
To enable the scenario and make it more "Windows friendly", the criteria on
when a file is considered public should be relaxed. One proposal is to check
whether the user has given EVERYONE group permission on the file only (and
discard the +x check on parent folders).
Security considerations for the proposal: Default permissions on Unix platforms
are usually "775" or "755" meaning that OTHER users can read and list folders
by default. What this also means is that Hadoop users have to explicitly make
the files private in order to make them private in the cluster (please correct
me if this is not the case in real life!). On Windows, default permissions are
"700". This means that by default all files are private. In the new model, if
users want to make them public, they have to explicitly add EVERYONE group
permissions on the file.
TestTrackerDistributedCacheManager fails because of this issue.
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