[DISCUSS] Allow user to create bucket with non-s3-naming-convention

[Dave Teng <dt...@cloudera.com.INVALID>]

Hello Ozone community!

This is Dave from Cloudera!

I have a use case/proposal that I'd like to hear from you guys! Currently I
heard that some HDFS migration cases translate the second level directory
names to Ozone bucket names.

However, some characters in the name of the directory compliant with
POSIX convention,
are not compliant with S3 naming rule, such as *underscore*.

Thus the original HDFS path which contains '_*' character is not allowed to
be put into Ozone because by default Ozone's path validation is the same as
S3. For such users, this proposal wishes to provide a way that when the
user gives a flag while creating the bucket via Ozone CLI (not from S3
interface), Ozone will allow '_*' only for such buckets. The idea is it'd
be the user's choice whether to create a non-s3 compliant bucket path or
not.  Ozone will keep equally supporting both OFS and S3 interfaces. For
pure file system background users, they may want to go ahead with this flag
by having the awareness that they may not be able to access the bucket
through S3 interface.



This Jira <https://issues.apache.org/jira/browse/HDDS-7585> is an umbrella
ticket that makes Ozone Bucket compatible with these two types of naming
convention, both POSIX and S3, to enable the HDFS to Ozone migration with
non s3 compliant paths.

 I currently have a POC PR <https://github.com/apache/ozone/pull/4037> of
the approach. I'd love to hear any feedback from the community!
Thank you!

(ps:

   - This proposal wouldn't change the default behavior of S3 bucket naming
   semantic in Ozone.


   - The documentation for new flag will be provided! )


Dave