Add KUBE_COVERAGE_FLUSH_INTERVAL to set flush interval.

pkg/util/coverage/coverage.go

@@ -29,7 +29,7 @@ import (
 	"time"
 )
 
-const flushInterval = 5 * time.Second
+var flushInterval = 5 * time.Second
 
 var coverageFile string
 
@@ -49,6 +49,10 @@ func InitCoverage(name string) {
 		coverageFile = "/tmp/k8s-" + name + ".cov"
 	}
 
+	if duration, err := time.ParseDuration(os.Getenv("KUBE_COVERAGE_FLUSH_INTERVAL")); err == nil {
+		flushInterval = duration
+	}
+
 	// Set up the unit test framework with the required arguments to activate test coverage.
 	flag.CommandLine.Parse([]string{"-test.coverprofile", tempCoveragePath()})