container/init: configurable lingering process wait delay

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/container.go

@@ -68,6 +68,8 @@ type (
 		Args []string
 		// Deliver SIGINT to the initial process on context cancellation.
 		ForwardCancel bool
+		// time to wait for linger processes after death of initial process
+		AdoptWaitDelay time.Duration
 
 		// Mapped Uid in user namespace.
 		Uid int
@@ -128,6 +130,14 @@ func (p *Container) Start() error {
 		p.SeccompPresets |= seccomp.PresetDenyTTY
 	}
 
+	if p.AdoptWaitDelay == 0 {
+		p.AdoptWaitDelay = 5 * time.Second
+	}
+	// to allow disabling this behaviour
+	if p.AdoptWaitDelay < 0 {
+		p.AdoptWaitDelay = 0
+	}
+
 	p.cmd = exec.CommandContext(ctx, MustExecutable())
 	p.cmd.Args = []string{initName}
 	p.cmd.Stdin, p.cmd.Stdout, p.cmd.Stderr = p.Stdin, p.Stdout, p.Stderr

container/init.go

@@ -17,9 +17,6 @@ import (
 )
 
 const (
-	// time to wait for linger processes after death of initial process
-	residualProcessTimeout = 5 * time.Second
-
 	/* intermediate tmpfs mount point
 
 	this path might seem like a weird choice, however there are many good reasons to use it:
@@ -358,7 +355,7 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 					msg.Verbosef("initial process exited with status %#x", w.wstatus)
 				}
 
-				go func() { time.Sleep(residualProcessTimeout); close(timeout) }()
+				go func() { time.Sleep(params.AdoptWaitDelay); close(timeout) }()
 			}
 		case <-done:
 			msg.BeforeExit()