Signal to stop a container.

Allow to set the signal to stop a container in `docker run`:
- Use `--stop-signal` with docker-run to set the default signal the container will use to exit.

Signed-off-by: David Calavera <david.calavera@gmail.com>

signal/signal.go

@@ -3,8 +3,12 @@
 package signal
 
 import (
+	"fmt"
 	"os"
 	"os/signal"
+	"strconv"
+	"strings"
+	"syscall"
 )
 
 // CatchAll catches all signals and relays them to the specified channel.
@@ -21,3 +25,20 @@ func StopCatch(sigc chan os.Signal) {
 	signal.Stop(sigc)
 	close(sigc)
 }
+
+// ParseSignal translates a string to a valid syscall signal.
+// It returns an error if the signal map doesn't include the given signal.
+func ParseSignal(rawSignal string) (syscall.Signal, error) {
+	s, err := strconv.Atoi(rawSignal)
+	if err == nil {
+		if s == 0 {
+			return -1, fmt.Errorf("Invalid signal: %s", rawSignal)
+		}
+		return syscall.Signal(s), nil
+	}
+	signal, ok := SignalMap[strings.TrimPrefix(strings.ToUpper(rawSignal), "SIG")]
+	if !ok {
+		return -1, fmt.Errorf("Invalid signal: %s", rawSignal)
+	}
+	return signal, nil
+}

signal/signal_unix.go

@@ -9,8 +9,11 @@ import (
 // Signals used in api/client (no windows equivalent, use
 // invalid signals so they don't get handled)
 
+const (
 	// SIGCHLD is a signal sent to a process when a child process terminates, is interrupted, or resumes after being interrupted.
-const SIGCHLD = syscall.SIGCHLD
-
+	SIGCHLD = syscall.SIGCHLD
 	// SIGWINCH is a signal sent to a process when its controlling terminal changes its size
-const SIGWINCH = syscall.SIGWINCH
+	SIGWINCH = syscall.SIGWINCH
+	// DefaultStopSignal is the syscall signal used to stop a container in unix systems.
+	DefaultStopSignal = "SIGTERM"
+)

signal/signal_windows.go

@@ -11,4 +11,6 @@ import (
 const (
 	SIGCHLD  = syscall.Signal(0xff)
 	SIGWINCH = syscall.Signal(0xff)
+	// DefaultStopSignal is the syscall signal used to stop a container in windows systems.
+	DefaultStopSignal = "15"
 )