server: graceful shutdown for fast failover. Fixes #308

cli/commands.go

@@ -2,6 +2,8 @@ package cli
 
 import (
 	"os"
+	"os/signal"
+	"syscall"
 
 	auditFile "github.com/hashicorp/vault/builtin/audit/file"
 	auditSyslog "github.com/hashicorp/vault/builtin/audit/syslog"
@@ -68,6 +70,7 @@ func Commands(metaPtr *command.Meta) map[string]cli.CommandFactory {
 					"transit":    transit.Factory,
 					"mysql":      mysql.Factory,
 				},
+				ShutdownCh: makeShutdownCh(),
 			}, nil
 		},
 
@@ -268,3 +271,20 @@ func Commands(metaPtr *command.Meta) map[string]cli.CommandFactory {
 		},
 	}
 }
+
+// makeShutdownCh returns a channel that can be used for shutdown
+// notifications for commands. This channel will send a message for every
+// interrupt or SIGTERM received.
+func makeShutdownCh() <-chan struct{} {
+	resultCh := make(chan struct{})
+
+	signalCh := make(chan os.Signal, 4)
+	signal.Notify(signalCh, os.Interrupt, syscall.SIGTERM)
+	go func() {
+		for {
+			<-signalCh
+			resultCh <- struct{}{}
+		}
+	}()
+	return resultCh
+}