Starting v2 release following API break

In cd60aa4, we changed the API leading
to issues like:
```
src/k8s.io/client-go/transport/round_trippers.go:70:11: cannot convert klog.V(9) (type klog.Verbose) to type bool
```

So we should move to v2 of klog

Change-Id: Ibf270e0e6dd326fa91d18140e92139455cbe4de0

.travis.yml

@@ -1,11 +1,10 @@
 language: go
-go_import_path: k8s.io/klog
+go_import_path: k8s.io/klog/v2
 dist: xenial
 go:
-  - 1.9.x
-  - 1.10.x
   - 1.11.x
   - 1.12.x
+  - 1.13.x
 script:
   - go get -t -v ./...
   - diff -u <(echo -n) <(gofmt -d .)

README.md

@@ -33,6 +33,8 @@ How to use klog
 - If you want to redirect everything logged using klog somewhere else (say syslog!), you can use `klog.SetOutput()` method and supply a `io.Writer`. (See `examples/set_output/usage_set_output.go`)
 - For more logging conventions (See [Logging Conventions](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-instrumentation/logging.md))
 
+**NOTE**: please use the newer go versions that support semantic import versioning in modules, ideally go 1.11.4 or greater.
+
 ### Coexisting with glog
 This package can be used side by side with glog. [This example](examples/coexist_glog/coexist_glog.go) shows how to initialize and syncronize flags from the global `flag.CommandLine` FlagSet. In addition, the example makes use of stderr as combined output by setting `alsologtostderr` (or `logtostderr`) to `true`.
 

examples/coexist_glog/coexist_glog.go

@@ -4,7 +4,7 @@ import (
 	"flag"
 
 	"github.com/golang/glog"
-	"k8s.io/klog"
+	"k8s.io/klog/v2"
 )
 
 func main() {

examples/klogr/main.go

@@ -3,8 +3,8 @@ package main
 import (
 	"flag"
 
-	"k8s.io/klog"
-	"k8s.io/klog/klogr"
+	"k8s.io/klog/v2"
+	"k8s.io/klog/v2/klogr"
 )
 
 type myError struct {

examples/log_file/usage_log_file.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"flag"
-	"k8s.io/klog"
+	"k8s.io/klog/v2"
 )
 
 func main() {

examples/set_output/usage_set_output.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"flag"
 	"fmt"
-	"k8s.io/klog"
+	"k8s.io/klog/v2"
 )
 
 func main() {

go.mod

@@ -1,4 +1,4 @@
-module k8s.io/klog
+module k8s.io/klog/v2
 
 go 1.12
 

integration_tests/internal/main.go

@@ -18,7 +18,7 @@ import (
 	"fmt"
 	"os"
 
-	"k8s.io/klog"
+	"k8s.io/klog/v2"
 )
 
 func main() {

klog_test.go

@@ -211,7 +211,7 @@ func TestHeaderWithDir(t *testing.T) {
 	pid = 1234
 	Info("test")
 	var line int
-	format := "I0102 15:04:05.067890    1234 klog/klog_test.go:%d] test\n"
+	format := "I0102 15:04:05.067890    1234 v2/klog_test.go:%d] test\n"
 	n, err := fmt.Sscanf(contents(infoLog), format, &line)
 	if n != 1 || err != nil {
 		t.Errorf("log format error: %d elements, error %s:\n%s", n, err, contents(infoLog))

klogr/klogr.go

@@ -10,7 +10,7 @@ import (
 	"sort"
 
 	"github.com/go-logr/logr"
-	"k8s.io/klog"
+	"k8s.io/klog/v2"
 )
 
 // New returns a logr.Logger which is implemented by klog.

klogr/klogr_test.go

@@ -5,7 +5,7 @@ import (
 	"flag"
 	"testing"
 
-	"k8s.io/klog"
+	"k8s.io/klog/v2"
 
 	"github.com/go-logr/logr"
 )