implement k8s service discovery (#988)

* implement k8s service discovery

* simplify code

* use default namespace if not provided

* disable codecov bot comment

* ignore adhoc dir

* simplify building target in NewClient

* reformat code

* Fix filepath (#990)

* format code, and reorg imports (#991)

* add more unit test

Co-authored-by: anqiansong <anqiansong@gmail.com>

core/proc/signals.go

@@ -1,3 +1,4 @@
+//go:build linux || darwin
 // +build linux darwin
 
 package proc
@@ -12,6 +13,8 @@ import (
 
 const timeFormat = "0102150405"
 
+var done = make(chan struct{})
+
 func init() {
 	go func() {
 		var profiler Stopper
@@ -33,6 +36,13 @@ func init() {
 					profiler = nil
 				}
 			case syscall.SIGTERM:
+				select {
+				case <-done:
+					// already closed
+				default:
+					close(done)
+				}
+
 				gracefulStop(signals)
 			default:
 				logx.Error("Got unregistered signal:", v)
@@ -40,3 +50,7 @@ func init() {
 		}
 	}()
 }
+
+func Done() <-chan struct{} {
+	return done
+}

core/proc/signals_test.go

@@ -0,0 +1,16 @@
+package proc
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDone(t *testing.T) {
+	select {
+	case <-Done():
+		assert.Fail(t, "should run")
+	default:
+	}
+	assert.NotNil(t, Done())
+}