fix(exec): pass -i to cocoon vm exec only when the caller attaches stdin#31
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cocoon v0.5.0 made vm exec stdin opt-in (docker semantics): without -i the child's stdin closes immediately. vk wired kubectl's stdin stream to the cocoon process unconditionally, so on v0.5.0+ hosts 'kubectl exec -i' delivers EOF instead of the caller's input. Map attach.Stdin() presence to -i: RunInContainer gets a nil reader when kubectl exec runs without -i, so stdin-less execs (including post-clone) keep their exact argv and no longer wire an unused pipe. Requires cocoon >= v0.5.0 for interactive execs (older cocoon rejects -i as an unknown flag); non-interactive execs are unaffected either way.
The -i opt-in landed in cocoon v0.4.8, not v0.5.0, and the note that stdin-less execs skip -i does not hold on the websocket exec path (its ignore-channel hands back a non-nil stdin reader), so the argv still carries -i there — harmless on cocoon >= v0.4.8. Describe what the code does instead of overstating the version/stream guarantees.
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Problem
cocoon v0.5.0 made
vm execstdin opt-in (docker semantics, cocoonstack/cocoon#119 area, commit 05dbae9): without-ithe child's stdin closes immediately. vk builds the exec argv without-iwhile unconditionally wiring kubectl's stdin stream to the cocoon subprocess — so on hosts running cocoon >= v0.5.0,kubectl exec -i(and-it) silently delivers EOF to the guest command instead of the caller's input.Fix
Map
attach.Stdin()presence to-i:RunInContainerreceives a nil stdin reader exactly when kubectl exec runs without-i, sostdin != nilis the interactive signal.-iprepended and the stream wired as before.exec.Cmdnil Stdin = /dev/null, matching the new cocoon semantics).Compatibility / rollout
-ias an unknown flag) — upgrade the cocoon binary before rolling this vk out. Note today's vk on cocoon v0.5.0 has interactive exec broken anyway, so ordering cocoon-first loses nothing.Testing
go build ./... && go test ./... && go vet ./...clean.TestBuildExecArgsAssemblesEnvAndArgvpinning-iplacement before-e.