We are internally Building both (proprietary) Engine code and Assets with Bazel.
Now for a new Project we use Unreal.
For Bazel the general direction is to get (transparent) caching and remote execution available to everyone. See this spec. We are working to get this available for our internal Bazel builds.
For our Unreal project we have similar requests.
Having worked with the Linux port and UBT in the past, I did take a look at current UBT. The internal action architecture seems to be quite compatible with the Action Caching of Bazel. As such my question is whether, if someone would extend UBT to make use of Bazels Action Cache, would you accept that for inclusion into UBT?
You might want to wait for an official answer, but Epic tends to accept improvements which are useful and implemented properly. The catch is that it usually takes around one year for them to merge your PR and in that year you must keep your changes up to date with any other changes that are made to the engine. They do seem to prioritize PRs based on popularity, so it could be longer or shorter depending on how many other people are clamoring for your contribution. Sometimes a campaign for your PR on the forums can help. Good luck.
I am curious to know if there has been any progress made toward this effort. Has there been any progress or is there anything out there addressing this?