HIVE-28059: Iceberg REST Catalog

[henrib]

What changes were proposed in this pull request?

This is a basic implementation of the Iceberg REST Catalog as a service embedded within HMS.

Why are the changes needed?

For Hive users that have started using Iceberg to store data and want to expose those same tables to external query engines, implementing the Iceberg REST catalog embedded within HMS allows an easy upgrade and deployment path.
Although a dedicated service to host the REST catalog is certainly desirable, it also implies deploying and managing another service.

Does this PR introduce any user-facing change?

It does since HMS then 'hosts' a servlet that implements the Iceberg REST Catalog API.

Is the change a dependency upgrade?

No.

How was this patch tested?

Unit tests.

(Restart of #5145 )

[sonarqubecloud]

Quality Gate passed

Issues
31 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[henrib]

All checks have passed :-)

[nrg4878]

Thank you for all the effort in implementing this feature, reviewing this PR and incorporating that feedback. Much much appreciated. @henrib @deniskuzZ @dengzhhu653 @zhangbutao @aturoczy @saihemanth-cloudera @InvisibleProgrammer

[deniskuzZ]

Special thanks to @henrib for your persistence, patience, and dedication in bringing this feature to completion!

[epilif1017a]

Hey everyone :) do we have docs on how to use this fantastic feature?

[aturoczy]

@epilif1017a In progress. As I know soon it will be documented

[epilif1017a]

@aturoczy Awesome 😎 thanks a lot! if you guys have some rough internal docs I'll take it as well! I'm starting a project where a modernized version of the hive metastore would come in handy and I'm battling out several client server dependency issues that the rest catalog would probably help surpass.

[zratkai]

@epilif1017a this is for Iceberg catalog, so if you use it for Iceberg related thing it should work, but for other may not.

[nrg4878]

We will work on enhancing the documentation. But meanwhile, perhaps the unit tests, that use http client, will give you an idea on how to use it.

[epilif1017a]

@epilif1017a this is for Iceberg catalog, so if you use it for Iceberg related thing it should work, but for other may not.

Precisely for that. @nrg4878 thanks for the tip! Will try it! Thank you so much for the direction.

Eager to see where hive metastore evolves in this era! Always been a fan of the project and I believe the metastore should continue to be a very important part of projects like Spark, Trino, etc. Maybe this rest based version is the way to move into a modernized era of the metastore! Have fun with the project. Thanks once again!