Refactor version helper (kubernetes#4437)

internal/nginx/main.go

@@ -23,10 +23,12 @@ import (
 	"io/ioutil"
 	"net/http"
 	"os"
+	"os/exec"
 	"strings"
 	"time"
 
 	"github.com/tv42/httpunix"
+	"k8s.io/klog"
 )
 
 // PID defines the location of the pid file used by NGINX
@@ -148,3 +150,21 @@ func buildUnixSocketClient(timeout time.Duration) *http.Client {
 		Transport: u,
 	}
 }
+
+// Version return details about NGINX
+func Version() string {
+	flag := "-v"
+
+	if klog.V(2) {
+		flag = "-V"
+	}
+
+	cmd := exec.Command("nginx", flag)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		klog.Errorf("unexpected error obtaining NGINX version: %v", err)
+		return "N/A"
+	}
+
+	return string(out)
+}

version/version.go

@@ -16,7 +16,11 @@ limitations under the License.
 
 package version
 
-import "fmt"
+import (
+	"fmt"
+
+	"k8s.io/ingress-nginx/internal/nginx"
+)
 
 var (
 	// RELEASE returns the release version
@@ -31,9 +35,10 @@ var (
 func String() string {
 	return fmt.Sprintf(`-------------------------------------------------------------------------------
 NGINX Ingress controller
-  Release:    %v
-  Build:      %v
-  Repository: %v
+  Release:       %v
+  Build:         %v
+  Repository:    %v
+  %v
 -------------------------------------------------------------------------------
-`, RELEASE, COMMIT, REPO)
+`, RELEASE, COMMIT, REPO, nginx.Version())
 }