fix(links): use sync.Once for singleton init and guard nil namespace#3147
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Aprazor wants to merge 1 commit intosrl-labs:mainfrom
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fix(links): use sync.Once for singleton init and guard nil namespace#3147Aprazor wants to merge 1 commit intosrl-labs:mainfrom
Aprazor wants to merge 1 commit intosrl-labs:mainfrom
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GetHostLinkNode and getMgmtBrLinkNode use a check-then-write pattern on package-level variables without synchronization. Since containerlab deploys nodes in parallel, concurrent goroutines could both read nil and race on the write. Replace the manual nil check with sync.Once for thread-safe init. Also fix a nil dereference: when ns.GetCurrentNS() fails, currns is nil but the code calls currns.Path() unconditionally, panicking. Now return early on error so the singleton remains nil rather than crashing.
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Summary
Two issues in the host and mgmt-net link node singletons:
1. Race condition on singleton initialization
GetHostLinkNode()andgetMgmtBrLinkNode()use a check-then-write pattern (if instance == nil { instance = ... }) on package-level variables without synchronization. Since containerlab deploys nodes in parallel (link resolution happens concurrently), two goroutines could both read nil and race on the write.Fix: Replace manual nil check with
sync.Oncefor thread-safe initialization.2. Nil dereference when GetCurrentNS fails
When
ns.GetCurrentNS()returns an error,currnsis nil. The code logs the error but unconditionally callscurrns.Path()on the next line, causing a nil pointer dereference panic.Fix: Return early on error so the singleton remains nil rather than crashing.
Testing
go vet ./links/...— cleango test -race ./links/...— all pass