Remove RapidJSON from Envoy

[htuch]

Now that v1 has been officially deprecated and is on track for removal in the near future, we shouldn't need RapidJSON anymore. All JSON parsing and printing should be possible via the protobuf library. This will simplify dependencies and reduce the trusted compute base.

[htuch]

@mattklein123 WDYT?

[htuch]

(CC @jmarantz who reminded me we can do this now ;) )

[mattklein123]

Sure, though I'm not sure we want to start ripping anything out until we wait a bit and see if anyone complains about v1 being gone? (Note also that RapidJSON is used for v1 schema)

[lizan]

FWIW, JWT auth filter still use it.

[htuch]

@lizan I think any users can be converted fairly mechanically to using protobuf, since they can just switch to using Struct and then doing (de)serialization.

[htuch]

Also CC @aa-stripe in the context of #4693

[qiwzhang]

In that case, I need to switch this repo: https://github.com/google/jwt_verify_lib
to use protobuf first before you can give ride of RapidJson

[htuch]

@qiwzhang ack. I think if we can at least try and avoid any new users of RapidJSON we can make this easier. @qiwzhang do you think it's reasonable to rewrite to using Struct + Protobuf<->JSON?

If this turns out to be too much of a pain, or there are other advantages of RapidJSON (better formatting, better error messages), we can stick with status quo.

[qiwzhang]

I can try, it should not be that difficult.

[ramaraochavali]

admin interface that displays stats in json format still uses it

[htuch]

@ramaraochavali yeah, but that should be possible to convert. I think everything internal to Envoy should not be a huge problem, it's more sticky with external deps though.

[stale]

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