Support arbitrary initial height

[erikgrinaker]

Summary

In tendermint/tendermint#5191 (will be released in 0.34.0-rc3), Tendermint added support for starting from an arbitrary initial height, given to the application via RequestInitChain.initial_height. IAVL added support for starting from an arbitrary version in cosmos/iavl#299 (released in 0.15.0-rc1). The SDK will need to configure itself accordingly.

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[alexanderbez]

We probably need to write up an ADR for how to support this and the expected use-cases. Thanks @erikgrinaker.

[erikgrinaker]

The primary use-case would be for e.g. the Cosmos Hub upgrade to Stargate to continue from the same block height as the previous chain, see RFC-002 for details.

[alexanderbez]

@zmanian do we want to do this for stargate? We're gonna need to get at the very least:

• ADR
• Implementation (hopefully super trivial)
• Simulation updates to test this new flow
• Integration tests to test this new flow

[zmanian]

Yeah I want this for stargate and I willing to help with above

[alexanderbez]

tm-rc3 has been released, correct @erikgrinaker? I'm thinking this might be easier than I thought -- I think we can just pass the last version (height) from BaseApp to RequestInitChain.initial_height. I'd like a version of Tendermint I can run this theory on. I think @marbar3778 has a WIP branch, but afaik, that doesn't build and/or run, correct @marbar3778?

[erikgrinaker]

Yes, rc3 is out. Not sure what you mean by passing from BaseApp; Tendermint/genesis specifies the initial height, not the app.

[tac0turtle]

. I'd like a version of Tendermint I can run this theory on. I think @marbar3778 has a WIP branch, but afaik, that doesn't build and/or run, correct @marbar3778?

Nope it runs. I had a testnet running and zakis testnet is with my wip branch

[alexanderbez]

@erikgrinaker right, I meant we load that height from the request.

[aaronc]

In discussing with @marbar3778, there are basically two things we need to do:

• handle initial_height in InitChain
• export height + in ExportGenesis

[alexanderbez]

Yes, this is what I also had in mind as the core components to look at. I believe the latter will be trivial, whereas the former we'll need to maybe load that height at the very beginning of InitChain.