From 023ccd99f50780bb954a5b034d655ce757b7e1ef Mon Sep 17 00:00:00 2001
From: ravisantoshgudimetla <ravisantoshgudimetla@gmail.com>
Date: Mon, 9 Oct 2017 18:01:55 -0400
Subject: [PATCH] Introducing versioning in descheduler

Signed-off-by: ravisantoshgudimetla <ravisantoshgudimetla@gmail.com>
---
 Makefile                       | 11 ++++-
 cmd/descheduler/app/version.go | 86 ++++++++++++++++++++++++++++++++++
 cmd/descheduler/descheduler.go |  1 +
 3 files changed, 96 insertions(+), 2 deletions(-)
 create mode 100644 cmd/descheduler/app/version.go

diff --git a/Makefile b/Makefile
index 9c493d4a8..b00e53c72 100644
--- a/Makefile
+++ b/Makefile
@@ -15,15 +15,22 @@
 .PHONY: test
 
 # VERSION is currently based on the last commit
-VERSION:=$(shell git rev-parse --short HEAD)
+VERSION=`git describe --tags`
+COMMIT=`git rev-parse HEAD`
+BUILD=`date +%FT%T%z`
+LDFLAG_LOCATION=github.com/kubernetes-incubator/descheduler/cmd/descheduler/app
+
+LDFLAGS=-ldflags "-X ${LDFLAG_LOCATION}.version=${VERSION} -X ${LDFLAG_LOCATION}.buildDate=${BUILD} -X ${LDFLAG_LOCATION}.gitCommit=${COMMIT}"
+
 
 # IMAGE is the image name of descheduler
+# Should this be changed?
 IMAGE:=descheduler:$(VERSION)
 
 all: build
 
 build:
-	go build -o _output/bin/descheduler github.com/kubernetes-incubator/descheduler/cmd/descheduler
+	go build ${LDFLAGS} -o _output/bin/descheduler github.com/kubernetes-incubator/descheduler/cmd/descheduler 
 
 image: build
 	docker build -t $(IMAGE) .
diff --git a/cmd/descheduler/app/version.go b/cmd/descheduler/app/version.go
new file mode 100644
index 000000000..020dfd32f
--- /dev/null
+++ b/cmd/descheduler/app/version.go
@@ -0,0 +1,86 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package app
+
+import (
+	"fmt"
+	"github.com/spf13/cobra"
+	"runtime"
+	"strings"
+)
+
+var (
+	// gitCommit is a constant representing the source version that
+	// generated this build. It should be set during build via -ldflags.
+	gitCommit string
+	// version is a constant representing the version tag that
+	// generated this build. It should be set during build via -ldflags.
+	version string
+	// buildDate in ISO8601 format, output of $(date -u +'%Y-%m-%dT%H:%M:%SZ')
+	//It should be set during build via -ldflags.
+	buildDate string
+)
+
+// Info holds the information related to descheduler app version.
+type Info struct {
+	Major      string `json:"major"`
+	Minor      string `json:"minor"`
+	GitCommit  string `json:"gitCommit"`
+	GitVersion string `json:"gitVersion"`
+	BuildDate  string `json:"buildDate"`
+	GoVersion  string `json:"goVersion"`
+	Compiler   string `json:"compiler"`
+	Platform   string `json:"platform"`
+}
+
+// Get returns the overall codebase version. It's for detecting
+// what code a binary was built from.
+func Get() Info {
+	majorVersion, minorVersion := splitVersion(version)
+	return Info{
+		Major:      majorVersion,
+		Minor:      minorVersion,
+		GitCommit:  gitCommit,
+		GitVersion: version,
+		BuildDate:  buildDate,
+		GoVersion:  runtime.Version(),
+		Compiler:   runtime.Compiler,
+		Platform:   fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH),
+	}
+}
+
+func NewVersionCommand() *cobra.Command {
+	var versionCmd = &cobra.Command{
+		Use:   "version",
+		Short: "Version of descheduler",
+		Long:  `Prints the version of descheduler.`,
+		Run: func(cmd *cobra.Command, args []string) {
+			fmt.Printf("Descheduler version %+v\n", Get())
+		},
+	}
+	return versionCmd
+}
+
+// splitVersion splits the git version to generate major and minor versions needed.
+func splitVersion(version string) (string, string) {
+	if version == "" {
+		return "", ""
+	}
+	// A sample version would be of form v0.1.0-7-ge884046, so split at first '.' and
+	// then return 0 and 1+(+ appended to follow semver convention) for major and minor versions.
+	return strings.Trim(strings.Split(version, ".")[0], "v"), strings.Split(version, ".")[1] + "+"
+}
diff --git a/cmd/descheduler/descheduler.go b/cmd/descheduler/descheduler.go
index 0d6fa8379..1e26646d2 100644
--- a/cmd/descheduler/descheduler.go
+++ b/cmd/descheduler/descheduler.go
@@ -25,6 +25,7 @@ import (
 func main() {
 	out := os.Stdout
 	cmd := app.NewDeschedulerCommand(out)
+	cmd.AddCommand(app.NewVersionCommand())
 	if err := cmd.Execute(); err != nil {
 		fmt.Println(err)
 		os.Exit(1)