Handle relationship between boxo and go-car and go-merkledag

[BigLep]

Current

Done criteria

boxo/car is removed. boxo will use ipld/go-car.

vvv OLD vvv

Done Criteria

Decision is made on the relation to be had between ipfs/boxo and ipld/go-car and ipfs/go-merkledag. This could mean having a dependency on ipfs/boxo (e.g., ipfs/go-merkledag#100 ) or boxo taking a fork of the relevant functionality it needs and maintaining it.

Why Important

The #196 effort (and particularly #206) can't be completed without decisions here, and that work is blocking other refactoring work like #176.

Resulting Actions

Below are the actions that are being taken as a result of the 2023-03-21 meeting:

✅ Item 1: Get go-car decoupled:

• @Jorropo (with @rvagg review) revert deprecation to ipfs/go-block-format that was done in refactor: deprecate and add stub types to go-libipfs/blocks go-block-format#37
  • Revert deprecation and go-libipfs/blocks stub types  go-block-format#41
• @Jorropo release ipfs/go-block-format
• @Jorropo (with @rvagg review) replace go-libipfs/blocks with ipfs/go-block-format in ipld/go-car. (Includes removing dependency in ipld/go-car on ipfs/go-libipfs)
• @Jorropo replace go-libipfs/blocks with ipfs/go-block-format in ipfs/go-unixfs
• @Jorropo remove dependency in ipfs/go-unixfs on ipfs/go-libipfs: remove go-libipfs dependency go-unixfs#146

✅ Item 2: copy in go-merkledag to boxo
This will get handled as part of #202
A row will be added for go-merkledag.
No deprecated types will be added.
A CODOWNERS will be added.
ipfs/go-merkledag#101

Additional items that have come up since>

1. ✅ Surface this with maintainers (folks in PL EngRes #bedrock): https://filecoinproject.slack.com/archives/C03FK0JJ10E/p1680108077842429
2. Clarify that boxo/ipld/car is not intended as a replacement for ipld/go-car: Clarify ipld/car relatioship with ipld/go-car #244

[BigLep]

2023-03-21 Sync Meeting

Attendees

1. @BigLep
2. @Jorropo
3. @guseggert
4. @rvagg
5. @DVD

Goals

My primary goal in this conversation is how to best enable Bedrock to detach from the "boxo" effort, while also unblocking #196

Agenda

Item 1: what to do with go-car

• It already uses go-libipfs for go-libipfs/blocks per https://github.com/ipld/go-car/blob/794f22231c0526e1123ee2a11bbc1567f9a011ae/go.mod#L9. That said, I want to see if that should be backed off given feat: upgrade from go-block-format to go-libipfs/blocks ipld/go-car#356 was merged without what I think was proper maintainer input from current maintainers (Bedrock team).
• I think there is an action item to specify CODEOWNERS for the repo and potentially reduce "ipld/w3dt-stewards" permissions.

Item 2: what to do with go-merkledag

• bump: go-libipfs go-merkledag#100
• Option 1: add dependency on boxo
• Option 2:
  • copy into Boxo (at which point ipfs/kubo-maintainers take maintainership of their copy)
  • don't add deprecated types
  • add CODEOWNERS to https://github.com/ipfs/go-merkledag for clarity
  • add notification to https://github.com/ipfs/go-merkledag about better alternatives
  • add signposts between boxo and go-merkledag about similar implementations

Item 3: any other disagreements that Rod wants to share? (Also encourage written thoughts to be shared publicly. They can be posted in this issue.)

[BigLep]

2023-03-21 meeting notes

Note @BigLep is not great at listening well and taking notes. Below is some of what was covered...

Rod:
go-car and go-merkledag are different ends of the spectrum

go-merkledag is not something that IPFS implementations should depend on.
It shouldn't be permanent.
These aren't important things that should need for an IPFS implementation
There is worry that it will become ore ossified by being in "boxo"
Wants to see it die.
Don't want to care about it.
General worry is that by pulling all this stuff in, that are crowding out the ability for people to make their own choices about what libraries to use (that can't as easily mix and match components).

go-car
Yes want to opt out of having a Boxo dependency.

Meta feedback
Need to get people onboard with making changes
If haven't gotten EngRes onboard, how about the rest of the ecosystem?

Currently has low trust towards Kubo maintainers as...

1. See things getting merged without proper time open or owner review(example: go-car with a dependency on go-libipfs)
2. Making decisions quickly without community involvement (e.g., changing name of go-libipfs)

Maybe can do a migration/breakage campaign but it can't be continual and it needs to be well thought through. Don't want to experience the repeated set of breakages like had with go-libp2p.

Steve:
We're not in a position right now to lead a fully buttoned-up migration campaign. Focus is on how we decouple to not so Kubo maintainer work is not impacting Bedrock.

dvd:
summary of the concerns:

1. communication about changes
2. get buy-in
3. avoid breaking changes

Steve:
Full acknowledgment that ipld/go-car#356 was not handled correctly. It shouldn't have been merged.

[There were other things, but the above was the gist I got written down.]

defer:
Discussion on bitswap in boxo.

Action Items

Actions around go-car and go-merkledag were added to the top-level description.

[BigLep]

Clarifying ownershp of go-car and requiring CODEOWNER PR approval is happening in:
ipld/go-car#403
ipld/github-mgmt#51