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cli/connhelper/commandcon.New: pass context with WithoutCancel #5816

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Merged
vvoland merged 1 commit into from
Feb 11, 2025
Merged

cli/connhelper/commandcon.New: pass context with WithoutCancel #5816

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22 changes: 16 additions & 6 deletions cli/connhelper/commandconn/commandconn.go
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Original file line number Diff line number Diff line change
Expand Up @@ -33,18 +33,28 @@ import (
)

// New returns net.Conn
func New(_ context.Context, cmd string, args ...string) (net.Conn, error) {
var (
c commandConn
err error
)
c.cmd = exec.Command(cmd, args...)
func New(ctx context.Context, cmd string, args ...string) (net.Conn, error) {
// Don't kill the ssh process if the context is cancelled. Killing the
// ssh process causes an error when go's http.Client tries to reuse the
// net.Conn (commandConn).
//
// Not passing down the Context might seem counter-intuitive, but in this
// case, the lifetime of the process should be managed by the http.Client,
// not the caller's Context.
//
// Further details;;
//
// - https://github.com/docker/cli/pull/3900
// - https://github.com/docker/compose/issues/9448#issuecomment-1264263721
ctx = context.WithoutCancel(ctx)
c := commandConn{cmd: exec.CommandContext(ctx, cmd, args...)}
Comment on lines +36 to +50
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@thaJeztah thaJeztah Feb 10, 2025 •
edited
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I was THIS close to passing the context, when I recalled there was some change related to this code to not pass it.

So instead, I passed through the context (which could be used to pass a context logger), and added a WithoutCancel ... and a large comment explaining why to prevent future others (or future self) from reintroducing the issue that was fixed (which may be even more relevant if this code is moved to a separate module)

// we assume that args never contains sensitive information
logrus.Debugf("commandconn: starting %s with %v", cmd, args)
c.cmd.Env = os.Environ()
c.cmd.SysProcAttr = &syscall.SysProcAttr{}
setPdeathsig(c.cmd)
createSession(c.cmd)
var err error
c.stdin, err = c.cmd.StdinPipe()
if err != nil {
return nil, err
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