A new format library was introduced for CEL in 4.18, but, it is not usable in 4.18 due to upgrade checks put in place (to allow version skew between API servers and rollbacks).

This means that the library is actually only presently usable in 4.19 once 1.32 ships. However, there are some issues we may face.

We have a number of APIs in flight currently that would like to use this new library, we cannot get started on those features until this library is enabled.

Some of those features would also like to be backported to 4.18.

We also have risks on upgrades. If we decide to use this format library in any API that is upgraded prior to KAS, then during an upgrade, the CRD will be applied to the older version of the API server, blocking the upgrade as it will fail.

By backporting the library (pretending it was introduced earlier, and then introducing it directly into 4.17), we can enable anything that installs post KAS upgrade to leverage this from 4.18 (solving those features asking for backports), and enable anything that upgrades pre-kas to actually leverage this in 4.19.

API approvers will be responsible for making sure the libraries and upgrade compatibility are considered as new APIs are introduced.

Presently, the library has had no bug fixes applied to the release-1.31 or release-1.32 branches upstream. The backport from 4.18 to 4.17 was clean bar some conflict in the imports that was easily resolved. So I'm confident that if we do need to backport any bug fixes, this should be straight forward.

Any bugs in these libraries can be assigned to me (jspeed)

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