main.go integration test for Startup interrupting.

cmd/prometheus/main_test.go

@@ -14,11 +14,98 @@
 package main
 
 import (
+	"flag"
+	"fmt"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
 	"testing"
+	"time"
 
 	"github.com/prometheus/prometheus/util/testutil"
 )
 
+var promPath string
+var promConfig = filepath.Join("..", "..", "documentation", "examples", "prometheus.yml")
+
+func TestMain(m *testing.M) {
+	var err error
+	promPath, err = os.Getwd()
+	if err != nil {
+		fmt.Printf("can't get current dir :%s \n", err)
+		os.Exit(1)
+	}
+	promPath = filepath.Join(promPath, "prometheus")
+
+	flag.Parse()
+	if !testing.Short() {
+		build := exec.Command("go", "build", "-o", promPath)
+		output, err := build.CombinedOutput()
+		if err != nil {
+			fmt.Printf("compilation error :%s \n", output)
+			os.Exit(1)
+		}
+
+		exitCode := m.Run()
+		os.Remove(promPath)
+		os.Exit(exitCode)
+	}
+}
+
+// As soon as prometheus starts responding to http request should be able to accept Interrupt signals for a gracefull shutdown.
+func TestStartupInterrupt(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test in short mode.")
+	}
+
+	prom := exec.Command(promPath, "--config.file="+promConfig)
+	err := prom.Start()
+	if err != nil {
+		t.Errorf("execution error: %v", err)
+		return
+	}
+
+	done := make(chan error)
+	go func() {
+		done <- prom.Wait()
+	}()
+
+	var startedOk bool
+	var stoppedOk bool
+	var stoppedErr error
+
+Loop:
+	for x := 0; x < 10; x++ {
+
+		// error=nil means prometheus has started so can send the interrupt signal and wait for the grace shutdown.
+		if _, err := http.Get("http://localhost:9090/graph"); err == nil {
+			startedOk = true
+			prom.Process.Signal(os.Interrupt)
+			select {
+			case stoppedErr = <-done:
+				stoppedOk = true
+				break Loop
+			case <-time.After(10 * time.Second):
+
+			}
+			break Loop
+
+		}
+		time.Sleep(500 * time.Millisecond)
+	}
+
+	if !startedOk {
+		t.Errorf("prometheus didn't start in the specified timeout")
+		return
+	}
+	if err := prom.Process.Kill(); err == nil && !stoppedOk {
+		t.Errorf("prometheus didn't shutdown gracefully after sending the Interrupt signal")
+	} else if stoppedErr != nil {
+		t.Errorf("prometheus exited with an error:%v", stoppedErr)
+	}
+}
+
 func TestComputeExternalURL(t *testing.T) {
 	tests := []struct {
 		input string