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[WIP] do not open stdin fifo when exec #10082

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[WIP] do not open stdin fifo when exec #10082

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5 changes: 0 additions & 5 deletions cmd/containerd-shim-runc-v2/process/exec.go
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Expand Up @@ -208,11 +208,6 @@
close(e.waitBlock)
return e.parent.runtimeError(err, "OCI runtime exec failed")
}
if e.stdio.Stdin != "" {
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I don't think it's correct. containerd supports exec operation with input. Please add your motivation. Thanks

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containerd/cmd/containerd-shim-runc-v2/process/exec.go

Line 240 in 6e0dc9f

sc, err := fifo.OpenFifo(context.Background(), path, syscall.O_WRONLY|syscall.O_NONBLOCK, 0)
openStdin opens fifo with O_WRONLY，which is only used to hold fifo write endpoint. For init process，it is important to prevent init process sigpipe when restart containerd, but for exec process, when restart containerd, exec process quit is what we want. Stdin copy for exec process parent.Platform.CopyConsole and pio.Copy will open stdin fifo with O_RDONLY in their own logic.

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@yuqitao yuqitao Apr 19, 2024 •
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I want to use this patch to solve pty device leak in CopyConsole. When restart containerd, there is no fifo write endpoint, copy stdin goroutine in CopyConsole will read EOF, and shutdown epollConsole.

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Synced with @yuqitao offline. I think the right approach is to implement exec operation's GC in CRI level or high-level plugin. The cleanup should be handled async. Since pod exec probe can go crazy, shim could have a lot of running exec processes. It could take time to cleanup. To avoid slow starting, we should handle it async.

if err := e.openStdin(e.stdio.Stdin); err != nil {
return err
}
}
ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
defer cancel()
if socket != nil {
Expand All @@ -236,7 +231,7 @@
return nil
}

func (e *execProcess) openStdin(path string) error {

Check failure on line 234 in cmd/containerd-shim-runc-v2/process/exec.go

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func `(*execProcess).openStdin` is unused (unused)
sc, err := fifo.OpenFifo(context.Background(), path, syscall.O_WRONLY|syscall.O_NONBLOCK, 0)
if err != nil {
return fmt.Errorf("failed to open stdin fifo %s: %w", path, err)
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