Sleep before context cancellation

README.md

@@ -94,6 +94,11 @@ Commands using this framework implement these external specifications:
 
     This is used internally for graceful restart.
 
+* `CANCELLATION_DELAY_SECONDS`
+
+    After `SIGINT` or `SIGTERM` received, the signal handler waits for the seconds before cancelling the context.
+    The default value is 5 sec.
+
 Usage
 -----
 

go.mod

@@ -8,3 +8,5 @@ require (
 	github.com/spf13/viper v1.3.2
 	golang.org/x/net v0.0.0-20190921015927-1a5e07d1ff72
 )
+
+go 1.13

signal.go

@@ -4,12 +4,18 @@ import (
 	"errors"
 	"os"
 	"os/signal"
+	"strconv"
+	"time"
 
 	"github.com/cybozu-go/log"
 )
 
 var (
 	errSignaled = errors.New("signaled")
+
+	cancellationDelaySecondsEnv = "CANCELLATION_DELAY_SECONDS"
+
+	defaultCancellationDelaySeconds = 5
 )
 
 // IsSignaled returns true if err returned by Wait indicates that
@@ -28,6 +34,23 @@ func handleSignal(env *Environment) {
 		log.Warn("well: got signal", map[string]interface{}{
 			"signal": s.String(),
 		})
+		delayStr := os.Getenv(cancellationDelaySecondsEnv)
+		delay, err := strconv.Atoi(delayStr)
+		if err != nil {
+			log.Warn("well: set default cancellation delay seconds", map[string]interface{}{
+				"env":   delayStr,
+				"delay": defaultCancellationDelaySeconds,
+			})
+			delay = defaultCancellationDelaySeconds
+		}
+		if delay < 0 {
+			log.Warn("well: round up negative cancellation delay seconds to 0s", map[string]interface{}{
+				"env":   delayStr,
+				"delay": 0,
+			})
+			delay = 0
+		}
+		time.Sleep(time.Duration(delay) * time.Second)
 		env.Cancel(errSignaled)
 	}()
 }