Move build's versioning bits under pkg/version

pkg/version/version.go

@@ -0,0 +1,80 @@
+/*
+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 version
+
+import (
+	"fmt"
+	"regexp"
+	"runtime"
+	"strings"
+)
+
+var (
+	// 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 $(date -u +'%Y-%m-%dT%H:%M:%SZ')
+	//It should be set during build via -ldflags.
+	buildDate string
+)
+
+// Info holds the information related to descheduler app version.
+type Info struct {
+	Major      string `json:"major"`
+	Minor      string `json:"minor"`
+	GitVersion string `json:"gitVersion"`
+	BuildDate  string `json:"buildDate"`
+	GoVersion  string `json:"goVersion"`
+	Compiler   string `json:"compiler"`
+	Platform   string `json:"platform"`
+}
+
+// Get returns the overall codebase version. It's for detecting
+// what code a binary was built from.
+func Get() Info {
+	majorVersion, minorVersion := splitVersion(version)
+	return Info{
+		Major:      majorVersion,
+		Minor:      minorVersion,
+		GitVersion: version,
+		BuildDate:  buildDate,
+		GoVersion:  runtime.Version(),
+		Compiler:   runtime.Compiler,
+		Platform:   fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH),
+	}
+}
+
+// splitVersion splits the git version to generate major and minor versions needed.
+func splitVersion(version string) (string, string) {
+	if version == "" {
+		return "", ""
+	}
+
+	// Version from an automated container build environment for a tag. For example v20200521-v0.18.0.
+	m1, _ := regexp.MatchString(`^v\d{8}-v\d+\.\d+\.\d+$`, version)
+
+	// Version from an automated container build environment(not a tag) or a local build. For example v20201009-v0.18.0-46-g939c1c0.
+	m2, _ := regexp.MatchString(`^v\d{8}-v\d+\.\d+\.\d+-\w+-\w+$`, version)
+
+	if m1 || m2 {
+		semVer := strings.Split(version, "-")[1]
+		return strings.Trim(strings.Split(semVer, ".")[0], "v"), strings.Split(semVer, ".")[1] + "+"
+	}
+
+	// Something went wrong
+	return "", ""
+}