Fix: change litep2p dependency from main to working tag

[metricaez]

Description:

litep2p dependency on main repository branch led to dependency breaking build because of type change.

Error log:

error[E0308]: mismatched types
   --> /Users/metricaez/.cargo/git/checkouts/polkadot-sdk-cff69157b985ed76/0bb6249/substrate/client/network/src/litep2p/discovery.rs:465:74
    |
465 |                 return Poll::Ready(Some(DiscoveryEvent::GetRecordSuccess { query_id, record }));
    |                                                                                      ^^^^^^ expected `Record`, found `PeerRecord`

For more information about this error, try `rustc --explain E0308`.
error: could not compile `sc-network` (lib) due to 1 previous error

Fix:

Move dependency to the stable tag v0.3.0

cc @Moliholy

[metricaez]

This would only fix polkadot-sdk release branch, fix should be further propagated.

[alexggh]

I'm not sure I understand how the release branch was broken, we do have a Cargo.lock, so the release branch should already build against a compatible litep2p, what am I missing ?

[metricaez]

Hi!

I encountered this issue while updating a parachain to v1.11.

source = "git+https://github.com/paritytech/litep2p?branch=master#e03a6023882db111beeb24d8c0ceaac0721d3f0f"
This was the commit hash our Cargo.lock pointed after the upgrade and it was breaking the build with the shared log, to fix it we had to manually modify to:
source = "git+https://github.com/paritytech/litep2p?branch=master#b142c9eb611fb2fe78d2830266a3675b37299ceb"
Which is the release commit of the proposed tag.

Could you please verify?

[Moliholy]

Furthermore, pointing dependencies to non-stable branches might break parachains at some point, even when Polkadot itself does not modify its own source code, but the dependency does. This is a bad practice that must be avoided at all cost.

For instance, a parachain running cargo update would break after new commits have been added to the sub-dependency's master branch, as the sub-dependency is not pinned to a stable commit hash.

In this scenario, any parachain trying to migrate to v1.11.0 will break, and the fix is not straightforward. This also means that the polkadot-v1.11.0 tag is not usable. Check here. Same for the release-polkadot-v1.11.0 branch as it is right now.

[alexggh]

Ok, I see your usecase, I thought you were just compiling polkadot-sdk from release branch and that should not be broken.

The fix seems about right, but it seems you updated a lot more dependencies in the Cargo.lock, you need to make sure that litep2p is the only one changing version in the Cargo.lock.

FYI @lexnv @dmitry-markin @EgorPopelyaev.

[alexggh]

Until, this gets fix in the release branch the fastest way to unblock you would be to add a cargo patch in your main Cargo.toml that pins litep2p to a compatible version, something like this should fix your build.

[patch."https://github.com/paritytech/litep2p"]
litep2p = { git = "https://github.com/paritytech//litep2p", tag = "COMPATIBLE_TAG" }

[metricaez]

Understood, yes a Cargo.lock update is implicit since it was rebuilt on testing, I can clean it :)

[lexnv]

I've created a PR to unblock this use-case by bringing the latest version: #4344 to substrate.

The breaking changes introduced by the PeerRecord where needed to have parity between libp2p and litep2p, as well as to unblock #3786 (which will be the main user of the peer records). The lastest version contains other fixes would be beneficial for litep2p users (mainly a panic on different than expected keys).

I've created a new PR since this one includes lots of dependency updates, which leads me to believe a cargo update was executed. We normally have to review and vet all crate version bumps to not depend on unwanted code.

Ideally, we'll switch soon the litep2p to a crate release schedule instead of depending on the master branch / having git dependencies which will make things more stable for end-users.

In the meanwhile, if you are interested in using litep2p you could specify it in the command line like --network-backend litep2p, your feedback would be greatly appreciate and would help move things faster 🙏

Again, apologies for the inconvenience and hope that PR fixes the issue, let us know if you need further assistance