SOLR-10391: Add overwrite option to UPLOAD ConfigSet action

[tflobbe]

When set to true, Solr will overwrite an existing configset in ZooKeeper if an UPLOAD action happens on an existing configset.
A new cleanup parameter can also be passed to let Solr know what to do with the files that existed in the old configset, but no longer exist in the new configset (remove or keep)

[epugh]

I wish we followed REST approaches for so many of our API's... Each one has a slightly different semantics for basic CRUD. Wish we had:

CRUD       HTTP
Create      POST
Read         GET
Update     PUT
Delete      DELETE

[HoustonPutman]

I agree with @epugh on the whole REST thing.

I also think that the default behavior should be that files that aren't present in the new configSet should be removed. I can see the use case for keeping old files around, but I think most people would want to update all files together. I could be wrong about that though.

[tflobbe]

I wish we followed REST approaches for so many of our API's

I wish that too, but Solr APIs aren't REST as of today (not even V2 API is fully REST, and this was intentional AFAIK, things like MODIFYCOLLECTION in V2 API are still POSTs requests). I think I'd rather keep consistency with other APIs than make this particular one better?

I also think that the default behavior should be that files that aren't present in the new configSet should be removed.

I was planning to add that as a different PR but also making it not-default, mostly because it can be pretty destructive (i.e. you created the zip file incorrectly, or created it with the "conf" directory on top or something like that it could remove all files) but I'm fine if people think it should be the default. Also, are you OK with doing that as a different PR or want me to do the change here? My intention was to keep the PR small for easier reviews, but if we think this feature is incomplete without that I can do it here too, I'm fine either way.

[HoustonPutman]

We might want to clear data that the znode has if it exists and has data.

[tflobbe]

Can that ever happen in a configset?

[HoustonPutman]

Not very likely, was just thinking about possibilities. It's probably not an issue 99.9% of times, so it likely doesn't need to be addressed.

[tflobbe]

Yes, I don't think this would be needed at this point. No API would set this, and no Solr component would read it. I guess the only case would be a custom component that writes and reads directly to ZooKeeper.

[tflobbe]

I plan to merge this tomorrow