rpcserver: return consistent grpc NotFound error for GetChaninfo & LookupInvoice #10064

ellemouton · 2025-07-10T09:25:19Z

Replaces #9810
Commit author credit has been retained 👍

This PR fixes the GetChanInfo endpoint so that it returns the correct grpc status code in the
case where the channel is not found.

LookupInvoice is also fixed to behave correctly in regards to this grpc status code.

The GetChanInfo fix is needed for the "remote graph" project so that we can correctly convert NotFound
errors back to graphdb.ErrEdgeNotFound errors.

So that we can properly convert this NotFound error back to our `graphdb.ErrEdgeNotFound` error if we are making this call to another node via RPC.

For a kvdb backed invoices DB, we sometimes will return the ErrNoInviocesCreated error if no invoices have ever been created on the node. In these cases we should still wrap the returned error in the grpc NotFound code.

gemini-code-assist

Summary of Changes

Hello @ellemouton, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on improving the consistency and predictability of gRPC error responses within the rpcserver, specifically for 'not found' scenarios. By standardizing the NotFound status code for channel and invoice lookups, it enhances the reliability of API interactions and supports downstream systems that rely on precise error interpretation. The changes are thoroughly validated with new integration tests.

Highlights

Consistent gRPC Error Handling: I've updated the rpcserver to return a consistent codes.NotFound gRPC status code for GetChanInfo when a channel is not found (specifically, when graphdb.ErrEdgeNotFound occurs). This is crucial for external projects, like the 'remote graph' project, to correctly interpret these errors.
Invoice Lookup Error Consistency: The LookupInvoice RPC now also returns codes.NotFound not only when a specific invoice is not found (invoices.ErrInvoiceNotFound) but also when no invoices have been added to the database yet (invoices.ErrNoInvoicesCreated), ensuring more consistent error reporting.
New Integration Test: I've added a new integration test, testGRPCNotFound, to verify that various RPC endpoints, including GetChanInfo, GetNodeInfo, SendCustomMessage, LookupHTLCResolution, and LookupInvoice, correctly return the codes.NotFound gRPC status when querying for non-existent entities.
Testing Helper Functions: To facilitate robust testing of gRPC error codes, I've introduced new AssertErr helper functions in the lntest/rpc/lnd.go package for GetChanInfo, GetNodeInfo, SendCustomMessage, LookupInvoice, and LookupHTLCResolution.

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Code Review

This pull request correctly updates GetChanInfo and LookupInvoice to return a consistent gRPC NotFound error, which is a good improvement for API consistency. The changes are well-supported by a new integration test that also covers other related RPCs, ensuring broader correctness.

My feedback is mainly focused on improving documentation and comments to align with the project's style guide, particularly regarding the 80-character line length limit. Overall, this is a solid contribution.

docs/release-notes/release-notes-0.20.0.md

lntest/rpc/lnd.go

guggero

Very nice! LGTM 🎉

Abdulkbk · 2025-07-10T16:15:53Z

lntest/rpc/lnd.go

 	require.ErrorContains(h, err, errStr)
 }

+// GetChanInfoAssertErr makes an RPC call to GetChanInfo and asserts an error


TIL about creating such test utility methods and can see how useful they are. My question is, when one needs to use them and is not sure of the exact error msg, is it safe to pass an empty string "" as an arg?

Hmm, that would look weird to me and I'd probably point it out in a PR I was reviewing. The other pattern we sometimes do is instead have a GetXXXErr (instead of GetXXXAssertErr) function that asserts there is an error and then returns the error. Then you can inspect the type/message of the error in the itest (if there are multiple options).

yyforyongyu

Thanks for picking this up! LGTM🦾

yyforyongyu · 2025-07-14T02:25:53Z

itest/lnd_misc_test.go

+	require.NoError(ht, err)
+
+	_, err = rand.Read(rHash)
+	require.NoError(ht, err)


nit: just fyi there are ht.Random32Bytes() and ht.RandomPreimage()

cool - gonna do this in a commit in the migration plugin /itest follow up PR I open today 👍

torkelrogstad and others added 2 commits July 10, 2025 11:21

rpcserver: return consistent grpc NotFound error for GetChaninfo

7a52b6c

So that we can properly convert this NotFound error back to our `graphdb.ErrEdgeNotFound` error if we are making this call to another node via RPC.

rpcserver: catch extra err case in LookupInvoice

23c3aaa

For a kvdb backed invoices DB, we sometimes will return the ErrNoInviocesCreated error if no invoices have ever been created on the node. In these cases we should still wrap the returned error in the grpc NotFound code.

ellemouton force-pushed the getChanInfoGrpcErr branch from 0e04c0e to a5d5172 Compare July 10, 2025 09:25

gemini-code-assist bot reviewed Jul 10, 2025

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ellemouton mentioned this pull request Jul 10, 2025

rpc: proper error code for GetChanInfo #9810

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torkelrogstad added 2 commits July 10, 2025 11:36

itest+lntest: add grpc NotFound error code test

c8b04d0

docs: update release notes

ed7b056

ellemouton force-pushed the getChanInfoGrpcErr branch from a5d5172 to ed7b056 Compare July 10, 2025 09:36

ellemouton requested review from yyforyongyu and guggero July 10, 2025 10:27

ellemouton self-assigned this Jul 10, 2025

guggero approved these changes Jul 10, 2025

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Abdulkbk approved these changes Jul 10, 2025

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yyforyongyu approved these changes Jul 14, 2025

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ellemouton merged commit add81f1 into lightningnetwork:master Jul 14, 2025
39 of 40 checks passed

ellemouton deleted the getChanInfoGrpcErr branch July 14, 2025 06:34

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rpcserver: return consistent grpc NotFound error for GetChaninfo & LookupInvoice #10064

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