feat: Add version flag

Signed-off-by: Justin Toh <tohjustin@hotmail.com>

internal/version/version.go

@@ -0,0 +1,48 @@
+package version
+
+import (
+	"fmt"
+	"runtime"
+)
+
+var (
+	gitMajor     string // major version, always numeric
+	gitMinor     string // minor version, numeric possibly followed by "+"
+	gitVersion   string // semantic version, derived by build scripts
+	gitCommit    string // sha1 from git, output of $(git rev-parse HEAD)
+	gitTreeState string // state of git tree, either "clean" or "dirty"
+	buildDate    string // build date in ISO8601 format, output of $(date -u +'%Y-%m-%dT%H:%M:%SZ')
+)
+
+// Info defines the version.
+type Info struct {
+	Major        string `json:"major,omitempty"`
+	Minor        string `json:"minor,omitempty"`
+	GitVersion   string `json:"gitVersion,omitempty"`
+	GitCommit    string `json:"gitCommit,omitempty"`
+	GitTreeState string `json:"gitTreeState,omitempty"`
+	BuildDate    string `json:"buildDate,omitempty"`
+	GoVersion    string `json:"goVersion,omitempty"`
+	Compiler     string `json:"compiler,omitempty"`
+	Platform     string `json:"platform,omitempty"`
+}
+
+// Get returns metadata and information regarding the version.
+func Get() Info {
+	return Info{
+		Major:        gitMajor,
+		Minor:        gitMinor,
+		GitVersion:   gitVersion,
+		GitCommit:    gitCommit,
+		GitTreeState: gitTreeState,
+		BuildDate:    buildDate,
+		GoVersion:    runtime.Version(),
+		Compiler:     runtime.Compiler,
+		Platform:     fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH),
+	}
+}
+
+// String returns info as a human-friendly version string.
+func (info Info) String() string {
+	return info.GitVersion
+}

pkg/cmd/lineage/lineage.go

@@ -114,6 +114,7 @@ func New(streams genericclioptions.IOStreams) *cobra.Command {
 	o.ConfigFlags.AddFlags(cmd.Flags())
 	o.PrintFlags.AddFlags(cmd.Flags())
 	addLogFlags(cmd.Flags())
+	addVersionFlag(cmd)
 
 	return cmd
 }
@@ -202,6 +203,7 @@ func (o *CmdOptions) Validate() error {
 		return errors.New("client config, client must be provided")
 	}
 
+	klog.V(4).Infof("Version: %s", getVersion())
 	klog.V(4).Infof("Namespace: %s", o.Namespace)
 	klog.V(4).Infof("Resource: %s", o.Resource)
 	klog.V(4).Infof("ResourceName: %s", o.ResourceName)

pkg/cmd/lineage/version.go

@@ -0,0 +1,17 @@
+package lineage
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"github.com/tohjustin/kube-lineage/internal/version"
+)
+
+func getVersion() string {
+	return fmt.Sprintf("%#v", version.Get())
+}
+
+func addVersionFlag(c *cobra.Command) {
+	c.Version = getVersion()
+	c.SetVersionTemplate("{{printf \"%s\" .Version}}\n")
+}